<h5 class="wp-block-heading" id="h-fda-now-recommends-genetic-testing-before-prescribing-specific-chemotherapy-medications">FDA Now Recommends Genetic Testing Before Prescribing Specific Chemotherapy Medications</h5>



For years, patient advocates have been calling for stronger safeguards against preventable toxicity from chemotherapy. Last week, the FDA took a major step forward, updating the label for a drug called <a href="https://medlineplus.gov/druginfo/meds/a699003.html" target="_blank" rel="noreferrer noopener">capecitabine</a> to explicitly recommend testing for variants in the DPYD gene before starting treatment. This is more than just a label change—it&#8217;s a long-awaited acknowledgment that genetics matter when it comes to patient safety.



<h2 class="wp-block-heading">What is DPYD?</h2>



The <a href="https://medlineplus.gov/genetics/gene/dpyd/" target="_blank" rel="noreferrer noopener">DPYD gene</a> provides instructions for making an enzyme called DPD (dihydropyrimidine dehydrogenase), which helps the body break down certain chemotherapy drugs like capecitabine and <a href="https://medlineplus.gov/druginfo/meds/a682708.html" target="_blank" rel="noreferrer noopener">5-fluorouracil</a>. These medications are commonly used to treat breast, colorectal, and other cancers. People with certain changes in this gene may not process these drugs properly, causing the drugs to build up in the body and, in some cases, leading to severe or even life-threatening <a href="https://medlineplus.gov/genetics/condition/dihydropyrimidine-dehydrogenase-deficiency/" target="_blank" rel="noreferrer noopener">reactions</a>.



<figure class="wp-block-image alignleft size-full is-resized"><img loading="lazy" decoding="async" width="508" height="531" src="http://35.88.189.111/wp-content/uploads/2025/10/drug-bottle.png" alt="" class="wp-image-34304" style="width:126px;height:auto" srcset="https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/10/drug-bottle.png 508w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/10/drug-bottle-287x300.png 287w" sizes="auto, (max-width: 508px) 100vw, 508px" /></figure>



These reactions can include painful mouth sores, severe diarrhea, low white blood cell counts, and nerve problems. <a href="https://medlineplus.gov/genetics/condition/dihydropyrimidine-dehydrogenase-deficiency/#frequency" target="_blank" rel="noreferrer noopener">Up to 8%</a> of people have a variant in the DPYD gene that affects how well they process these medications. Sadly, some patients with DPYD variants have died after receiving these drugs. Such experiences have fueled years of advocacy calling for genetic testing before treatment, not after. 



<h2 class="wp-block-heading" id="h-a-change-in-the-recommendations">A change in the recommendations</h2>



Until now, the FDA advised doctors they could &#8220;consider testing&#8221; patients before giving capecitabine or similar drugs. The <a href="https://www.accessdata.fda.gov/drugsatfda_docs/label/2025/020896s052lbl.pdf" target="_blank" rel="noreferrer noopener">new label</a> goes much further, adding a warning that says, &#8220;serious adverse reactions or death may occur in patients with complete DPD deficiency&#8221; and telling doctors to test for DPYD variants before prescribing the medication. (Experts predict a similar change to the 5-fluorouracil drug label soon.) It&#8217;s a major win for patient safety and for the <a href="https://test4dpd.org/" target="_blank" rel="noreferrer noopener">advocacy groups</a> who have pushed tirelessly for this change. Organizations that have long advocated for universal DPYD testing hope this update will encourage hospitals and cancer centers across the U.S. to make pretreatment genetic testing standard care.



<figure class="wp-block-image alignright size-large is-resized"><img loading="lazy" decoding="async" width="790" height="1024" src="http://35.88.189.111/wp-content/uploads/2020/09/PGt-Home-790x1024.png" alt="23andMe mobile pharmacogenomics" class="wp-image-28527" style="width:256px;height:auto" srcset="https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2020/09/PGt-Home-790x1024.png 790w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2020/09/PGt-Home-231x300.png 231w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2020/09/PGt-Home-768x996.png 768w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2020/09/PGt-Home-679x880.png 679w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2020/09/PGt-Home-910x1180.png 910w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2020/09/PGt-Home.png 1583w" sizes="auto, (max-width: 790px) 100vw, 790px" /></figure>



We share the belief that genetic insights can empower individuals and help improve outcomes. The 23andMe® <a href="https://www.23andme.com/topics/pharmacogenetics/dpyd/" target="_blank" rel="noreferrer noopener">DPYD Drug Metabolism Pharmacogenetics report</a>*, available to <a href="https://www.23andme.com/membership/" target="_blank" rel="noreferrer noopener">23andMe+ Premium</a>™ members, provides information about two variants associated with reduced DPD enzyme activity. While this report isn&#8217;t a substitute for clinical testing, it can help people learn whether they carry certain DPYD variants and start a conversation with their healthcare provider. 



The FDA&#8217;s new label is an important step toward safer, more personalized cancer treatment and a long-awaited victory for the patients and advocates who made their voices heard.



<hr class="wp-block-separator has-alpha-channel-opacity"/>



 * 23andMe PGS Pharmacogenetics reports: The 23andMe test uses qualitative genotyping to detect 3 variants in the CYP2C19 gene, 2 variants in the DPYD gene and 1 variant in the SLCO1B1 gene in the genomic DNA of adults from saliva for the purpose of reporting and interpreting information about the processing of certain therapeutics to inform discussions with a healthcare professional. It does not describe if a person will or will not respond to a particular therapeutic. Our CYP2C19 Pharmacogenetics report provides certain information about variants associated with metabolism of some therapeutics and provides interpretive drug information regarding the potential effect of citalopram and clopidogrel therapy. Our SLCO1B1 Pharmacogenetics report provides certain information about variants associated with the processing of some therapeutics and provides interpretive drug information regarding the potential effect of simvastatin therapy. Our DPYD Pharmacogenetics report does not describe the association between detected variants and any specific therapeutic. Results for DPYD and certain CYP2C19 results should be confirmed by an independent genetic test prescribed by your own healthcare provider before taking any medical action. Warning: Test information should not be used to start, stop, or change any course of treatment and does not test for all possible variants that may affect metabolism or protein function. The PGS test is not a substitute for visits to a healthcare professional. Making changes to your current regimen can lead to harmful side effects or reduced intended benefits of your medication, therefore consult with your healthcare professional before taking any medical action. For important information and limitations regarding Pharmacogenetic reports, visit <a href="http://23andme.com/test-info/pharmacogenetics/" target="_blank" rel="noreferrer noopener">23andme.com/test-info/pharmacogenetics/</a>

A Big Step Forward for Patient Safety

Late in the first quarter in only his third game this season, one professional football team’s star edge-rusher limped off the field, gesturing to his trainers with his thumb down. Apparently, he already knew what he&#8217;d find out a short time later with an MRI: he&#8217;d again torn his ACL, the anterior cruciate ligament.



While a hard tackle or awkward fall can tear an ACL, some people may be more prone to an ACL tear than others, and their genetics may explain why.



A new 23andMe polygenic risk score (PRS) report sheds light on that genetic connection. The report examines how a person&#8217;s genetics may impact their likelihood of experiencing an ACL tear, an injury particularly common among those involved in high-impact sports.



<h2 class="wp-block-heading" id="h-how-genetics-may-influence-acl-tear-risk">How Genetics May Influence ACL Tear Risk</h2>



First, it&#8217;s important to note that your genetics is only one part of the story – many other factors can influence the risk of an ACL tear. 



<figure class="wp-block-image alignright size-full"><img loading="lazy" decoding="async" width="306" height="126" src="http://35.88.189.111/wp-content/uploads/2025/10/ACL-tear-PRS-Hero.png" alt="" class="wp-image-34316" srcset="https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/10/ACL-tear-PRS-Hero.png 306w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/10/ACL-tear-PRS-Hero-300x124.png 300w" sizes="auto, (max-width: 306px) 100vw, 306px" /></figure>



Tears typically occur when the knee twists or extends beyond its normal range, often seen in sports that involve jumping and sudden stops, pivots, or changes in direction. That might be in sports such as football, soccer, basketball, or downhill skiing. The ACL is the most commonly injured ligament in the knee.&nbsp;&nbsp;



We also know that ACL tears are more common in female athletes. However, because more males participate in high-risk sports, the total number of ACL tears may actually be higher in males. They are also more likely in people with a family history of an ACL injury or a personal history of an ACL tear. Indeed, genetics plays an important role, with one 2020 sports medicine journal study estimating the <a href="https://bjsm.bmj.com/content/55/7/385" target="_blank" rel="noreferrer noopener">genetic contribution to an ACL tear at approximately 69 percent</a>. 



While the exact biological mechanism involved is not yet known, the genetic associations do offer some hints. Among the many genetic variants associated with ACL tears are variants in or near genes involved in the formation of collagen, a building block for ligaments. Scientists have discovered other variants linked to tears, but most of those associations are inconclusive, and more research is needed.&nbsp;



<h2 class="wp-block-heading" id="h-23andme-s-new-acl-tear-prs-report">23andMe&#8217;s New ACL Tear PRS Report</h2>



Knowing how genetics influences the risk for an ACL tear can empower athletes, who are at the highest risk, train smarter and work toward preventing them.&nbsp;



To create the new ACL Tear PRS Report* 23andMe scientists analyzed data from people who consented to participate in research to identify thousands of variants associated with ACL tears. The 23andMe scientists then created a genetic model that incorporated those variants to calculate the genetic likelihood of an ACL tear.



This PRS report, like other 23andMe PRS reports, is research-based and not validated for medical diagnostic use; it may have limitations for people with mixed or less-studied ancestries and does not account for every possible factor influencing ACL health. In addition, polygenic risk scores integrate many common variants, but they do not account for rare genetic variants or lifestyle factors that can heavily impact risk.&nbsp;



For individuals with an elevated genetic or family risk, creating a personalized prevention plan and scheduling regular check-ins with sports medicine professionals are great ways to keep knees healthy.&nbsp;



<h2 class="wp-block-heading" id="h-mitigating-the-risk-of-acl-tears">Mitigating the Risk of ACL Tears</h2>



Whether you’re a pro athlete or not, and especially if you’ve already had an ACL tear before, proper training and technique&nbsp; are simple ways to help lower the likelihood of injury.



Here are a few things you can do to help lower the risk of an ACL tear:



<ul class="wp-block-list">
<li>Build muscle strength in the hamstrings, and core to stabilize the knee.</li>



<li>Maintain proper technique for movements such as jumping, pivoting, and squatting — like landing on the balls of your feet with knees bent and keeping knees aligned over your toes.</li>



<li>Warm up and cool down before and after physical activity to increase flexibility.</li>



<li>Wear supportive, activity-appropriate footwear for correct alignment.</li>



<li>Consulting with physical therapists or trainers for form and strength assessments can further reduce the risk, regardless of one&#8217;s genetic background.</li>
</ul>



We continue to learn about the role genetics plays in sports-related injuries, including ACL tears, but genetics is just one factor.&nbsp;



<h2 class="wp-block-heading" id="h-learn-more">Learn More</h2>



<a href="https://www.23andme.com/membership/" target="_blank" rel="noreferrer noopener">23andMe+ Premium</a>™ members can view this report with their other Wellness reports.



<a href="https://you.23andme.com/" target="_blank" rel="noreferrer noopener">Sign in</a> to learn more about what 23andMe&#8217;s ACL Tear PRS can tell you. 



* The 23andMe ACL Tear PRS report is based on a genetic model that includes data and insights from 23andMe consented research participants and incorporates more than 6,000 genetic variants to provide information on the likelihood of experiencing an ACL tear. The report does not describe a person’s overall likelihood, does not account for lifestyle or family history and has not been reviewed by the US Food and Drug Administration. The ACL Tear PRS report is not intended to tell you anything about your current state of health, or to be used to make medical decisions or determine any treatment.

Genetics May Explain Why Some Athletes Are More Prone to ACL Tears

As many as one in 10 women have endometriosis, but diagnosing it can take up to a decade or more. Dive into the science, and learn a bit about a new 23andMe Endometriosis report that looks at the genetic likelihood of developing this painful condition.



<figure class="wp-block-image size-full"><img loading="lazy" decoding="async" width="612" height="252" src="http://35.88.189.111/wp-content/uploads/2025/09/endometriosis_hero-1.jpg" alt="" class="wp-image-34227" srcset="https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/09/endometriosis_hero-1.jpg 612w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/09/endometriosis_hero-1-300x124.jpg 300w" sizes="auto, (max-width: 612px) 100vw, 612px" /></figure>



Have you ever been told your debilitating period pain is &#8220;normal&#8221;? Do you find yourself planning your life around your cycle, canceling plans, or missing work or school due to pain, heavy bleeding, or exhaustion? If so, you&#8217;re not alone; these symptoms could point to endometriosis, a common, yet often misunderstood, condition.



For those with endometriosis, tissue similar to the lining of the uterus grows in other places, like the ovaries, fallopian tubes, or even the bowel and bladder. This can lead to severe pain, heavy periods, and in some cases, may make it harder to become pregnant (between 30–50% of women with endometriosis experience infertility).



If this sounds familiar, it’s important to know that your pain is real and more common than many people think. Endometriosis affects as many as 10% of women in the U.S. Despite this, the journey to a diagnosis can be frustratingly long, sometimes <a href="https://pubmed.ncbi.nlm.nih.gov/39373298/" target="_blank" rel="noreferrer noopener">taking up to 12 years</a>. This delay often happens because symptoms are dismissed as &#8220;just a bad period.&#8221;



To support awareness and help people understand their genetic predisposition to endometriosis, we’ve launched the new Endometriosis* report for female <a href="https://www.23andme.com/membership/" target="_blank" rel="noreferrer noopener">23andMe+ Premium</a>™ and <a href="https://www.23andme.com/total-health/" target="_blank" rel="noreferrer noopener">Total Health</a>™ members.



<h2 class="wp-block-heading" id="h-what-causes-endometriosis">What causes endometriosis?</h2>



While the exact cause isn&#8217;t known, several factors can increase your likelihood of developing endometriosis:



<figure class="wp-block-image alignright size-full is-resized"><img loading="lazy" decoding="async" width="612" height="720" src="http://35.88.189.111/wp-content/uploads/2025/09/Group-125628.png" alt="" class="wp-image-34211" style="width:259px;height:auto" srcset="https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/09/Group-125628.png 612w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/09/Group-125628-255x300.png 255w" sizes="auto, (max-width: 612px) 100vw, 612px" /></figure>



<ul class="wp-block-list">
<li>Age: It most often affects menstruating people and is frequently diagnosed in the 30s and 40s.</li>



<li>Family history: Having a family member with endometriosis increases risk.</li>



<li>Reproductive history: Starting menstruation at a young age, experiencing menopause later in life, and having frequent or heavy periods (short cycles or bleeding lasting more than 7 days) can all increase chances of developing the condition.</li>
</ul>



These factors are associated with a higher risk. On the other hand, having been pregnant or breastfeeding may reduce risk.



<h3 class="wp-block-heading" id="h-the-genetic-connection">The genetic connection</h3>



Endometriosis is what’s known as a <a href="https://www.genome.gov/genetics-glossary/Polygenic-Trait" target="_blank" rel="noreferrer noopener">polygenic</a> condition — meaning that many different genetic variants in many different genes can influence a person’s chances of developing it. In fact, <a href="https://pubmed.ncbi.nlm.nih.gov/26209831/" target="_blank" rel="noreferrer noopener">research suggests</a> that genetics may explain nearly half of the differences in who develops endometriosis across a population.



In 2023, 23andMe collaborated with researchers at Oxford in what was at the time the largest study on <a href="https://blog.23andme.com/articles/largest-genetic-study-to-date-links-endometriosis-with-chronic-pain" target="_blank" rel="noreferrer noopener">endometriosis and its association with chronic pain</a>. Now, to further understand the genetics of this condition, researchers at 23andMe looked at genetic and self-reported data from more than 1.5 million consented research participants. Using this information, they created a Polygenic Risk Score (PRS) — a model that considers thousands of genetic variants to estimate a person’s likelihood of developing endometriosis.



However, this model did not perform as accurately for 23andMe customers with Black or African American ancestry. Due to this limitation, we cannot provide a result for the Endometriosis report to those customers at this time. This is an important reminder that genetics research has historically underrepresented many communities. With continued research and broader participation, we hope to improve this work and reduce these disparities in the future.



<h2 class="wp-block-heading" id="h-what-you-can-do-about-it">What you can do about it</h2>



While the road to getting a diagnosis and managing endometriosis can be long and frustrating, there are proactive steps you can take on your journey to getting answers and feeling better.



<h3 class="wp-block-heading" id="h-advocate-for-yourself">Advocate for yourself</h3>



Track Your Symptoms. Before you see a doctor, consider starting a symptom diary. Being specific can make a big difference. Every day, note:



<ul class="wp-block-list">
<li>Pain: On a scale of 1–10, where is the pain, and what does it feel like (sharp, dull, cramping)?</li>



<li>Timing: When during your cycle do you feel symptoms? (During your period, during ovulation, all month long?)</li>



<li>Bleeding: How heavy is your flow? Are you passing clots?</li>



<li>Other Symptoms: Note any bloating, painful bowel movements, pain with sex, or fatigue.</li>



<li>Impact: How do these symptoms affect your daily life? (e.g., &#8220;Missed two days of work,&#8221; &#8220;Couldn&#8217;t exercise,&#8221; &#8220;Had to leave the party early.&#8221;)</li>
</ul>



Connect with a Doctor. Armed with your symptom diary, make an appointment with a healthcare provider.



<ul class="wp-block-list">
<li>Be clear and confident. Say, &#8220;I am concerned I might have endometriosis because of these specific symptoms.&#8221;</li>



<li>Don&#8217;t be afraid to ask questions. &#8220;What are the next steps for diagnosis?&#8221; or &#8220;Could we explore treatment options for my pain now?&#8221;</li>



<li>If you feel dismissed, get a second opinion. Look for a gynecologist who specializes in endometriosis or pelvic pain.</li>
</ul>



<h3 class="wp-block-heading" id="h-manage-symptoms">Manage symptoms</h3>



There’s no one-size-fits-all approach, but experts agree that certain lifestyle habits can make a difference:



<ul class="wp-block-list">
<li>Exercise: Activities like yoga can improve blood flow, relax muscles, and reduce pain.</li>



<li>Relaxation and self-care: Rest, warmth on the lower stomach (like a heating pad, warm water bottle, or bath), and gentle movement can help ease discomfort.</li>
</ul>



Medical options may include medications to manage pain and hormone levels, pelvic floor physical therapy, and in some cases, surgery. Because endometriosis tissue can respond to estrogen, symptoms may improve after menopause, when estrogen levels remain consistently low.



<h2 class="wp-block-heading" id="h-take-the-next-steps">Take the next steps</h2>



Endometriosis pain is not an exaggeration, and it deserves to be taken seriously. Seeking answers is the first and most powerful step toward managing your health and reclaiming your quality of life.



Ready to learn more about your health and genetics and take the next step in your journey? Learn more about <a href="https://www.23andme.com/membership/" target="_blank" rel="noreferrer noopener">23andMe+ Premium</a> or <a href="https://www.23andme.com/total-health/" target="_blank" rel="noreferrer noopener">Total Health</a> memberships.



Already part of 23andMe? <a href="https://you.23andme.com/" target="_blank" rel="noreferrer noopener">Sign in</a> to view this report with your other Health Predisposition reports or upgrade 23andMe+ Premium or Total Health memberships.



* The 23andMe Endometriosis PRS report is based on a genetic model that includes data and insights from 23andMe consented research participants and incorporates more than 13,000 genetic variants to provide information on the likelihood of developing endometriosis. The report does not describe a person’s overall likelihood, does not account for lifestyle or family history, and has not been reviewed by the US Food and Drug Administration. The Endometriosis PRS report is not intended to tell you anything about your current state of health, or to be used to make medical decisions or determine any treatment. 



NOTE: Within this blog post, we use the words &#8220;women&#8221; and &#8220;female&#8221; to refer to people whose sex assigned at birth is female. However, we recognize that not everyone who experiences endometriosis will identify as female, and being categorized by birth sex may be an uncomfortable experience for some people. We do not mean to delegitimize anyone’s gender identity. Learn more about why we made this decision in this <a href="https://customercare.23andme.com/hc/en-us/articles/360010964373-How-23andMe-Uses-Your-Genetic-Sex-Birth-Sex-and-Gender" target="_blank" rel="noreferrer noopener">help article</a>.

Could Your Painful Periods Be Endometriosis? Here’s What You Should Know

This week, 23andMe added a new genetic report to help us all be more aware of an often overlooked contributor to health disparities.



<figure class="wp-block-image alignright size-large is-resized"><img loading="lazy" decoding="async" width="1024" height="763" src="http://35.88.189.111/wp-content/uploads/2025/08/duffy-statistic-1024x763.png" alt="" class="wp-image-34101" style="width:309px;height:auto" srcset="https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/08/duffy-statistic-1024x763.png 1024w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/08/duffy-statistic-300x224.png 300w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/08/duffy-statistic-768x572.png 768w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/08/duffy-statistic-880x656.png 880w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/08/duffy-statistic-1180x879.png 1180w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/08/duffy-statistic.png 1224w" sizes="auto, (max-width: 1024px) 100vw, 1024px" /></figure>



<a href="https://pubmed.ncbi.nlm.nih.gov/35994632/" target="_blank" rel="noreferrer noopener">Nearly 70%</a> of Black and African Americans have two copies of a variant in the Duffy antigen gene that can cause them to have white blood cell (WBC) counts that are lower than most standard reference ranges.&nbsp;



People who have this genotype — called Duffy null status — do not have an increased risk for <a href="https://pubmed.ncbi.nlm.nih.gov/32959868/" target="_blank" rel="noreferrer noopener">infection</a> or <a href="https://pubmed.ncbi.nlm.nih.gov/39825822/" target="_blank" rel="noreferrer noopener">other health problems</a>. But they may be flagged incorrectly as having abnormally low WBC counts, which can negatively impact the healthcare they receive.&nbsp;



&#8220;I&#8217;ve seen patients that are told that they might have cancer, go through painful bone marrow biopsies, miss out on joining clinical trials, or have critical medications like chemotherapy discontinued simply because their white blood cell counts were interpreted without understanding their Duffy status,&#8221; says Dr. Lauren Merz, Assistant Professor of Medicine, Division of Hematology/Oncology at the University of Michigan, who is leading efforts to raise awareness about Duffy null status and develop Duffy null-specific reference ranges and who provided expert feedback on 23andMe&#8217;s new report.



<h2 class="wp-block-heading" id="h-when-a-one-size-fits-all-blood-test-falls-short">When a one-size-fits-all blood test falls short</h2>



When we have our blood drawn, testing labs use reference ranges to determine whether our results fall in the range considered &#8220;normal&#8221; or are too high or too low, which can flag the need for clinical follow-up. One common blood test measures neutrophils, which are a type of white blood cell that helps the body fight infections.



Most neutrophil reference ranges are defined based on populations where Duffy null status is rare, such as people with European or Asian genetic ancestry. And blood testing labs don&#8217;t usually take into account Duffy status. As a result, <a href="https://pubmed.ncbi.nlm.nih.gov/35994632/" target="_blank" rel="noreferrer noopener">nearly 25%</a> of healthy Black and African Americans with Duffy null status — and more than 15% of all Black and African Americans — have neutrophil counts below the standard reference range.



These individuals may be misdiagnosed with neutropenia (low neutrophil counts), which can lead to a number of downstream harms, including <a href="https://pubmed.ncbi.nlm.nih.gov/34180972/" target="_blank" rel="noreferrer noopener">unnecessary specialty referrals and follow-up tests</a> like bone marrow biopsies; <a href="https://pubmed.ncbi.nlm.nih.gov/39259539/" target="_blank" rel="noreferrer noopener">exclusion from clinical trials</a> (because many trials require a minimum number of neutrophils that is higher than the normal range for people with the Duffy null genotype); and delayed or reduced access to medications for <a href="https://pubmed.ncbi.nlm.nih.gov/39259539/" target="_blank" rel="noreferrer noopener">cancer</a>, <a href="https://pubmed.ncbi.nlm.nih.gov/34645395/" target="_blank" rel="noreferrer noopener">mental health conditions</a>, and <a href="https://pubmed.ncbi.nlm.nih.gov/35724382/" target="_blank" rel="noreferrer noopener">autoimmune disorders</a>. (See the sidebar at the bottom for more details.)



<h2 class="wp-block-heading" id="h-what-is-the-duffy-antigen-and-how-does-it-impact-white-blood-cells">What is the Duffy antigen, and how does it impact white blood cells?</h2>



<figure class="wp-block-image alignleft size-large is-resized"><img loading="lazy" decoding="async" width="87" height="138" src="http://35.88.189.111/wp-content/uploads/2021/11/research.b57972a5e8fa.svg" alt="an icon representing research" class="wp-image-29284" style="width:117px;height:auto"/></figure>



The Duffy antigen is a protein found on the surface of red blood cells and certain other cells in the body. People with two copies of a specific <a href="https://www.cincinnatichildrens.org/health/d/duffy-null-associated-neutrophil-count" target="_blank" rel="noreferrer noopener">genetic variant in the ACKR1 (Duffy antigen) gene</a> don&#8217;t express this protein on their red blood cells — giving rise to the name &#8220;Duffy null.&#8221;



Being Duffy null can also impact infection-fighting white blood cells called neutrophils. People who are Duffy null tend to have naturally lower levels of circulating neutrophils in the peripheral blood — <a href="https://pubmed.ncbi.nlm.nih.gov/37338884/" target="_blank" rel="noreferrer noopener">about 40% lower, on average</a>. But they don&#8217;t have an increased risk for infection, because the total number of neutrophils in their bodies remains the same. (Their neutrophils just move from the blood into other tissues like the spleen more easily.)



In the past, healthy people with low neutrophil counts were said to have &#8220;benign ethnic neutropenia,&#8221; because the Duffy null variant is more common in certain populations. But the preferred name is now <a href="https://www.cincinnatichildrens.org/health/d/duffy-null-associated-neutrophil-count" target="_blank" rel="noreferrer noopener">Duffy null-associated neutrophil count (DANC)</a>, as this refers to the biological driver of Duffy status rather than the social construct of race or ethnicity — and highlights that lower neutrophil counts are normal for people who are Duffy null.



<h2 class="wp-block-heading" id="h-is-duffy-null-status-associated-with-any-health-conditions">Is Duffy null status associated with any health conditions?</h2>



To date, there is no robust evidence that people with Duffy null status are at increased risk for any health conditions. In fact, a <a href="https://pubmed.ncbi.nlm.nih.gov/39825822/" target="_blank" rel="noreferrer noopener">recent, large phenome-wide association study (PheWAS)</a> — which looked for potential associations between the Duffy null variant and 1,400 possible health conditions using the National Institutes of Health&#8217;s All of Us initiative and other cohorts — did not report any associations with disease. However, this is an active area of research.



<h2 class="wp-block-heading" id="h-why-is-duffy-null-status-most-common-in-certain-populations">Why is Duffy null status most common in certain populations?</h2>



Although anyone can have Duffy null status, it is most common among people with African or Middle Eastern ancestry. In the U.S., two-thirds of people who identify as Black or African American have the Duffy null genotype, which means they do not express the Duffy antigen on their red blood cells.&nbsp;



Scientists believe this variant became common in certain populations because it <a href="https://pubmed.ncbi.nlm.nih.gov/21468018/" target="_blank" rel="noreferrer noopener">helps protect against Plasmodium vivax</a>, a malaria parasite that relies on the Duffy antigen to infect red blood cells. (The variant does not protect against other types of malaria.) Over generations, people in regions where this malaria parasite was widespread were more likely to inherit this protective variant, and it remains common today in people with ancestry from some malaria-endemic regions.



<figure class="wp-block-image size-full"><img loading="lazy" decoding="async" width="934" height="597" src="http://35.88.189.111/wp-content/uploads/2025/08/af_rs2814778_C.png" alt="" class="wp-image-34139" srcset="https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/08/af_rs2814778_C.png 934w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/08/af_rs2814778_C-300x192.png 300w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/08/af_rs2814778_C-768x491.png 768w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/08/af_rs2814778_C-880x562.png 880w" sizes="auto, (max-width: 934px) 100vw, 934px" /><figcaption class="wp-element-caption">23andMe data also show that the Duffy null genetic variant is most common in people with ancestry from parts of the world where Plasmodium vivax malaria is common.</figcaption></figure>



<h2 class="wp-block-heading" id="h-the-importance-of-raising-awareness">The importance of raising awareness</h2>



Last year, the American Society of Hematology (ASH) launched the <a href="https://www.hematology.org/education/danc/danc-project" target="_blank" rel="noreferrer noopener">Absolute Neutrophil Count (ANC) by Duffy Status Project</a>, aimed at creating specific neutrophil reference ranges for people with the Duffy null genotype and advocating for broader awareness and testing.



&#8220;The Duffy null genotype is a perfect example of how well-meaning systems can fall short when they don&#8217;t reflect the full diversity of the people they serve,&#8221; says Dr. Merz. &#8220;Raising awareness — among both clinicians and patients — is essential to prevent misdiagnosis and ensure more equitable and personalized care.&#8221;



You can become your own advocate by learning about your Duffy status and sharing that information with your doctor.&nbsp;



The White Blood Cell Count (Duffy Antigen-Related) report is available to <a href="https://www.23andme.com/membership/" target="_blank" rel="noreferrer noopener">23andMe+ Premium™ members</a> with their other Wellness reports.



<div style="float: left; text-align: justified; width: 700px; background-color: #eee; padding: 15px; margin-left: 5px;">
 
<h3>A deeper dive: How lack of awareness of Duffy null status can lead to downstream harm</h3>


Although Duffy null status does not usually cause health problems, harms can arise when Duffy null individuals are misdiagnosed with abnormally low neutrophil counts. These harms can include:
<ul>
<li>
Unnecessary follow-up testing. In general, low neutrophil counts can prompt concern from doctors, because they can be caused by blood cancers like leukemia. Follow-up testing involves a bone marrow biopsy, which is an invasive and sometimes painful test. 
 Because their neutrophil counts may be naturally lower than standard reference ranges, people with Duffy null status are much more likely to receive <a href="https://pubmed.ncbi.nlm.nih.gov/34180972/" target="_blank" rel="noreferrer noopener">unnecessary bone marrow biopsies</a>. And one study reported that Duffy null status was the <a href="https://pubmed.ncbi.nlm.nih.gov/37419240/" target="_blank" rel="noreferrer noopener">most common reason</a> for children to be referred to a children&#8217;s hospital for low neutrophil counts.
</li>
 
<li>
Exclusion from clinical trials. Many chemotherapy drugs reduce WBC production, which can make patients more susceptible to infections. As a result, most cancer clinical trials require patients to have a minimum neutrophil count before starting the trial, to help keep patients safe. 
 But a recent study found that more than 75% of cancer clinical trials have neutrophil thresholds that <a href="https://pubmed.ncbi.nlm.nih.gov/39259539/" target="_blank" rel="noreferrer noopener">exclude some people with Duffy null status</a>. Researchers have suggested these exclusion criteria may be one reason that Black Americans are <a href="https://pubmed.ncbi.nlm.nih.gov/37477920/" target="_blank" rel="noreferrer noopener">less likely to be included in cancer clinical trials</a>.
</li>
 
<li>
Delayed or reduced access to medications. Because some medications reduce WBC production, patients often have their neutrophils counted before and during treatment, so that their clinicians can adjust the dose, delay the start of treatment, or discontinue medications if counts become too low. 
 Because people with Duffy null status tend to have lower starting neutrophil counts, they may experience reduced or delayed access to important medications for <a href="https://pubmed.ncbi.nlm.nih.gov/39259539/" target="_blank" rel="noreferrer noopener">cancer</a>, <a href="https://pubmed.ncbi.nlm.nih.gov/34645395/" target="_blank" rel="noreferrer noopener">mental health conditions</a>, and <a href="https://pubmed.ncbi.nlm.nih.gov/35724382/" target="_blank" rel="noreferrer noopener">autoimmune disorders</a>, or inappropriate dose adjustments. Because chemotherapy dose often increases the chance of survival, some scientists think that inappropriate chemotherapy dosing related to Duffy null status could help explain, in part, why <a href="https://www.cancer.org/about-us/what-we-do/health-equity/cancer-disparities-in-the-black-community.html" target="_blank" rel="noreferrer noopener">breast cancer mortality is higher in Black than white Americans</a>.
</li>
</ul>

</div>

The Duffy Antigen Gene: A Clue Behind White Blood Cell Differences

We often hear about the &#8220;nature versus nurture&#8221; debate, framing it as a battle between our genes and our environment. But in many cases it&#8217;s not a battle at all, it&#8217;s a partnership. The way our genes impact our health and traits may change depending on our environment.



<figure class="wp-block-image size-large"><img loading="lazy" decoding="async" width="1024" height="684" src="http://35.88.189.111/wp-content/uploads/2022/09/GettyImages-981323210-1024x684.jpg" alt="" class="wp-image-30209" srcset="https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2022/09/GettyImages-981323210-1024x684.jpg 1024w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2022/09/GettyImages-981323210-300x200.jpg 300w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2022/09/GettyImages-981323210-768x513.jpg 768w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2022/09/GettyImages-981323210-880x587.jpg 880w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2022/09/GettyImages-981323210-1180x788.jpg 1180w" sizes="auto, (max-width: 1024px) 100vw, 1024px" /></figure>



Understanding both &#8220;nature&#8221; and &#8220;nurture&#8221; is especially important when we consider complex skills critical to success in life, like reading. Thanks to the contribution of over a million 23andMe® research participants, a <a href="https://pubmed.ncbi.nlm.nih.gov/40991152/" target="_blank" rel="noreferrer noopener">new study</a>, led by scientists from the University of Edinburgh, is helping to untangle how both genes and environment work to shape literacy.



<h2 class="wp-block-heading" id="h-the-reading-puzzle-nbsp">The Reading Puzzle&nbsp;</h2>



Literacy is a powerful predictor of life outcomes, from education level to income. For decades, researchers have tried to understand the roles genetics and environment play in why some people learn to read and spell more easily than others.



<figure class="wp-block-image alignleft size-full is-resized"><img loading="lazy" decoding="async" width="425" height="282" src="http://35.88.189.111/wp-content/uploads/2008/07/twins.jpg" alt="" class="wp-image-392" style="width:309px;height:auto" srcset="https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2008/07/twins.jpg 425w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2008/07/twins-300x199.jpg 300w" sizes="auto, (max-width: 425px) 100vw, 425px" /></figure>



Several <a href="https://pubmed.ncbi.nlm.nih.gov/23725549/" target="_blank" rel="noreferrer noopener">studies</a> of <a href="https://pubmed.ncbi.nlm.nih.gov/19076484/" target="_blank" rel="noreferrer noopener">twins</a> in the United States suggested an interaction between genes and environment. In these studies, how much influence genetics had on reading skills seemed to be higher in families with a higher socioeconomic status. In other words, genetics appeared to have a bigger impact on a child&#8217;s reading ability when they were in a more advantaged environment. This idea is called a gene-by-environment interaction.



However, the evidence of this gene-by-environment interaction was mixed in studies conducted in the <a href="https://pubmed.ncbi.nlm.nih.gov/19296213/" target="_blank" rel="noreferrer noopener">United Kingdom</a> and <a href="https://pubmed.ncbi.nlm.nih.gov/28832969/" target="_blank" rel="noreferrer noopener">Australia</a>. This puzzle led researchers to ask: can we use modern genetic data to test this theory in large, diverse populations?



<h2 class="wp-block-heading" id="h-a-new-approach">A New Approach</h2>



Researchers utilized summary statistics from a 2022 <a href="https://blog.23andme.com/articles/study-identifies-genetic-links-to-dyslexia" target="_blank" rel="noreferrer noopener">genome-wide association study (GWAS) on dyslexia</a> to construct a polygenic score—a way of estimating someone’s genetic tendency toward a trait by adding up the small effects of thousands of DNA differences.



The team then applied this polygenic score to two large groups of children and adolescents in Australia and the United Kingdom to see if the score&#8217;s effect on reading and spelling skills was moderated by their family&#8217;s socioeconomic status. Socioeconomic status was used as a broad measure of environmental advantage, capturing factors like parental education level and household income.&nbsp;



<h2 class="wp-block-heading" id="h-what-was-discovered-two-parallel-paths">What Was Discovered: Two Parallel Paths</h2>



Both the dyslexia polygenic score (nature) and socioeconomic status (nurture) were significant predictors of reading and spelling performance. Together, demographic, genetic, and socioeconomic factors explained between 8% and 11.6% of the variation in reading skills.



However, the study found no interaction effect. Nature and nurture were both important, but they worked in parallel.



This means the influence of a person&#8217;s genetic predisposition was the same, regardless of their family&#8217;s socioeconomic background. In these groups, a higher genetic predisposition for reading provided a similar boost to children from all socioeconomic backgrounds.&nbsp;



<h2 class="wp-block-heading" id="h-the-bigger-picture">The Bigger Picture</h2>



This finding is an important reminder to scientists to consider different environments when looking for gene-by-environment interactions. While some earlier US-based studies suggested an interaction, the different environments in these large UK and Australian groups showed a different outcome. Suggesting that both our genes and our environment make their own distinct contributions to the development of this fundamental skill.



Of course, every study has its limitations. The 23andMe research participants who contributed to the original GWAS are a self-selecting group and may not be perfectly representative of the general population. Additionally, only about 5% of 23andMe research participants said they had dyslexia, which is on the lower end of the <a href="https://pubmed.ncbi.nlm.nih.gov/18652545/" target="_blank" rel="noreferrer noopener">commonly cited 5–10% range</a>.



Even so, this large-scale study provides a crucial piece of the puzzle, emphasizing how vital it is to test scientific findings in diverse environments to get the full story.

Nature and Nurture: A New Look at the Genetics of Reading Ability

This week the American Society of Human Genetics (ASHG) is having its <a href="https://meetings.ashg.org/event/ASHG25/home/" target="_blank" rel="noreferrer noopener">annual meeting</a> in Boston. Attending the ASHG annual meeting is about more than just presenting our work, it&#8217;s one way we are working to ensure that the 23andMe® Research Institute contributes to a healthier future for everyone.



<ul class="wp-block-list">
<li>Amplifying impact: Sharing our discoveries with a global audience helps our work reach those who can build upon it, accelerating the path from discovery to clinic.</li>



<li>Fostering collaboration: It&#8217;s where we connect with the brightest minds in the field. These conversations spark new ideas and forge partnerships that are essential for tackling complex diseases.</li>



<li>Staying on the cutting edge: Exposure to the latest technologies and unpublished data keeps our research relevant and innovative.</li>
</ul>



<h2 class="wp-block-heading" id="h-23andme-research-institute-at-ashg">23andMe Research Institute at ASHG</h2>



For those attending, stop by our posters in the following sessions:



<div class="wp-block-columns is-layout-flex wp-container-core-columns-is-layout-28f84493 wp-block-columns-is-layout-flex">
<div class="wp-block-column is-layout-flow wp-block-column-is-layout-flow" style="flex-basis:66.66%">
WEDNESDAY, OCTOBER 15TH 2:30 &#8211; 4:30 PM (Posters; Board #2004W) Sustaining Research Ethics in Times of Change: A Framework from the 23andMe Research Program



presented by Emily DelloRusso, Principal Regulatory Science Manager
</div>



<div class="wp-block-column is-layout-flow wp-block-column-is-layout-flow" style="flex-basis:33.33%">
<figure class="wp-block-image size-large is-resized"><img loading="lazy" decoding="async" width="683" height="1024" src="http://35.88.189.111/wp-content/uploads/2025/10/image-683x1024.png" alt="" class="wp-image-34327" style="width:150px" srcset="https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/10/image-683x1024.png 683w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/10/image-200x300.png 200w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/10/image-768x1152.png 768w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/10/image-587x880.png 587w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/10/image-787x1180.png 787w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/10/image.png 1067w" sizes="auto, (max-width: 683px) 100vw, 683px" /></figure>
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THURSDAY, OCTOBER 16TH 2:30 &#8211; 4:30 PM (Posters; Board #2035T) Explore23: a privacy-forward, secure, extensible, and easy-to-use web application for exploration of a large genomic research cohort



presented by Julie Granka, Director, Statistical Genetics
</div>



<div class="wp-block-column is-layout-flow wp-block-column-is-layout-flow" style="flex-basis:33.33%">
<figure class="wp-block-image size-large is-resized"><img loading="lazy" decoding="async" width="819" height="1024" src="http://35.88.189.111/wp-content/uploads/2025/10/image-1-819x1024.png" alt="" class="wp-image-34328" style="width:150px" srcset="https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/10/image-1-819x1024.png 819w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/10/image-1-240x300.png 240w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/10/image-1-768x960.png 768w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/10/image-1-704x880.png 704w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/10/image-1-944x1180.png 944w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/10/image-1.png 1280w" sizes="auto, (max-width: 819px) 100vw, 819px" /></figure>
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<div class="wp-block-columns is-layout-flex wp-container-core-columns-is-layout-28f84493 wp-block-columns-is-layout-flex">
<div class="wp-block-column is-layout-flow wp-block-column-is-layout-flow" style="flex-basis:66.66%">
FRIDAY, OCTOBER 17TH 2:30 &#8211; 4:30 PM (Posters; Board #3014F) Learning about a genetic predisposition to depression is psychologically well tolerated among those with high polygenic risk scores



presented by Rebecca Berns, Sr. Product Scientist I, Genomic Health and Sciences
</div>



<div class="wp-block-column is-layout-flow wp-block-column-is-layout-flow" style="flex-basis:33.33%">
<figure class="wp-block-image size-large is-resized"><img loading="lazy" decoding="async" width="682" height="1024" src="http://35.88.189.111/wp-content/uploads/2025/10/image-2-682x1024.png" alt="" class="wp-image-34329" style="width:150px" srcset="https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/10/image-2-682x1024.png 682w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/10/image-2-200x300.png 200w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/10/image-2-768x1153.png 768w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/10/image-2-586x880.png 586w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/10/image-2-786x1180.png 786w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/10/image-2.png 1066w" sizes="auto, (max-width: 682px) 100vw, 682px" /></figure>
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Interested in reading more? 23andMe has contributed to <a href="https://research.23andme.com/publications/" target="_blank" rel="noreferrer noopener">more than 300 research publications</a>.

23andMe Research Institute Attending ASHG 2025

Cannabis is already one of the most widely used drugs globally, and its use will likely grow even more as it becomes more socially accepted and legally available. For many the recreational use of cannabis poses few problems, but for as many as a third of users, it becomes problematic developing into an addiction or what scientists call cannabis use disorder. Research suggests that genetics may explain why.



<h2 class="wp-block-heading" id="h-searching-the-genome-for-clues">Searching the Genome for Clues</h2>



In collaboration with 23andMe Research Institute, researchers at the University of California, San Diego <a href="https://www.nature.com/articles/s41380-025-03219-2" target="_blank" rel="noreferrer noopener">published a study</a> today that found genetic links to cannabis use as well as links to psychiatric, cognitive, and physical health. The researchers used data from more than 130,000 people who consented to participate in 23andMe research. Participants answered survey questions on whether they had ever used cannabis (“lifetime use”) and, for those who had, how often they used it during their heaviest 30-day period (“frequency of use”). The team then conducted genome-wide association studies searching for genetic variants linked to ever trying cannabis and how often people used the drug.



<h2 class="wp-block-heading" id="h-what-the-data-revealed">What the Data Revealed</h2>



Researchers found that having ever used cannabis was associated with two genetic regions: CADM2—a gene <a href="https://blog.23andme.com/articles/scientists-identify-genes-associated-with-cannabis-use" target="_blank" rel="noreferrer noopener">previously linked</a> to cannabis and other substance use, impulsivity, and risk-taking—and GRM3. While GRM3 has been tied to alcohol use, schizophrenia, and certain personality traits, this is the first time it’s been linked to cannabis use. How often someone used cannabis was associated with a different variant also near CADM2, strengthening this gene’s role in cannabis behaviors. Both having ever used cannabis and how frequently someone used cannabis were genetically linked to other substance use, pain, and psychiatric conditions like depression. Researchers also created polygenic scores—which tally the effects of many different genetic variants—to estimate both the likelihood of ever having used cannabis and the frequency of cannabis use. These polygenic scores were able to replicate associations between cannabis use and substance use and mood disorders in two other independent research datasets (All of Us and BioVU). The researchers also uncovered novel associations with anxiety, celiac disease, HIV, and viral hepatitis.



<h2 class="wp-block-heading" id="h-why-this-research-matters">Why This Research Matters</h2>



Most genetic research on cannabis has focused on two points in the spectrum: first use and cannabis use disorder. But the stages in between—like how often someone uses cannabis—are just as important. Studying these “pre-addiction” traits may help determine who is more likely to progress from a casual user to someone with cannabis use disorder. This study was one of the first genome wide association studies to look at traits that may lead to cannabis use disorder.&nbsp;



Traits like frequency of cannabis use can reveal genetic factors that shape vulnerability before addiction develops. Understanding these factors could eventually help predict risk for cannabis use disorder and related health conditions.



<h2 class="wp-block-heading" id="h-more-than-just-dna">More Than Just DNA</h2>



Like all research there are some important considerations to keep in mind for this study:



<ul class="wp-block-list">
<li>While this research focused on genetics, many non-genetic factors may also play a significant role in a person&#8217;s likelihood of using cannabis or developing cannabis use disorder.</li>



<li>The study was conducted in people of European descent (based on an analysis of their local genetic ancestry), so the findings may not fully apply to people of other ancestries.</li>



<li>The measure of frequency (use days in a 30-day window) of using cannabis doesn’t capture full patterns such as the duration of regular use or quantity consumed.</li>



<li>While GRM3 is a promising lead, more work is needed to understand how the genetic variant in this region affects cannabis use biology.</li>
</ul>



<h2 class="wp-block-heading" id="h-the-road-ahead">The Road Ahead</h2>



Future research will need to expand to larger and more diverse cohorts and include other cannabis-related traits such as craving, withdrawal, and response to cannabis. Combining genetic insights from multiple stages of cannabis use could:



<ul class="wp-block-list">
<li>Improve the discovery of new genetic variants</li>



<li>Help build predictive models for problematic use</li>



<li>Clarify how cannabis genetics intersect with physical and mental health</li>
</ul>



Takeaway: Studying genetic influences on early cannabis use behaviors could eventually help predict risk for cannabis use disorder and related health conditions, and may help shed light on who is most at risk for cannabis use disorder.&nbsp; These findings mark an important step toward understanding the genetics of cannabis use and its health consequences.

New Genetic Insights Into Cannabis Use

<h6 class="wp-block-heading" id="h-a-new-study-may-help-identify-and-more-quickly-help-the-60-of-people-with-major-depression-who-do-not-get-relief-from-their-initial-treatments">A new study may help identify and more quickly help the 60% of people with major depression who do not get relief from their initial treatments. </h6>



It is estimated that 60% of patients with major depressive disorder don&#8217;t find relief from their first medication, and as many as one-third develop <a href="https://pmc.ncbi.nlm.nih.gov/articles/PMC10503923/" target="_blank" rel="noreferrer noopener">treatment-resistant depression</a>, which is often defined as still experiencing symptoms after trying at least two antidepressants.



Researchers at Johnson &amp; Johnson and the 23andMe Research Institute used advanced machine learning techniques to accurately identify those at most risk for treatment-resistant depression, a massive breakthrough for those suffering with this condition.



The groundbreaking research, published this week in the journal <a href="https://pubmed.ncbi.nlm.nih.gov/41028019/" target="_blank" rel="noreferrer noopener">Scientific Reports</a>, used only self-reported information from about 23,000 people who consented to participate in 23andMe research. The model included a total of 101 predictive factors, including such things as age, symptoms that persist between episodes of depression, the duration of episodes of depression, stress levels, and suicidal thoughts. 



Using this predictive model, researchers were able to accurately predict those at the highest risk for treatment-resistant depression 78% of the time, according to the study.&nbsp;



The predictive model did not use either genetics or lab results, just questions that can be easily assessed by a clinician.



<h2 class="wp-block-heading">Why This Matters</h2>



<figure class="wp-block-image alignright size-full is-resized"><img loading="lazy" decoding="async" width="508" height="531" src="http://35.88.189.111/wp-content/uploads/2025/10/drug-bottle.png" alt="" class="wp-image-34304" style="width:161px;height:auto" srcset="https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/10/drug-bottle.png 508w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/10/drug-bottle-287x300.png 287w" sizes="auto, (max-width: 508px) 100vw, 508px" /></figure>



Typically, antidepressants used to treat major depression take a little time to work, up to a month or a month and a half. When a treatment does not work, clinicians often prescribe an alternative medication. When someone with depression fails to respond to at least two different medications, they are deemed to have treatment-resistant depression. In many cases, it can take around a year for someone to finally be diagnosed with treatment-resistant depression.



That long delay in finding effective treatment has a cost, not just in the time it takes to identify treatment but in the prolonged suffering for those in the throes of depression, unable to get relief.&nbsp;



The promise of the kind of predictive modeling described in this new study is that it would give both people with depression and clinicians who treat them a tool to flag those who might not respond to standard therapies.



Instead of waiting to see if initial treatments are effective, it may accelerate the process of finding alternatives. Additionally, this predictive model only utilizes patient-reported information; no expensive testing is required.&nbsp;



<h2 class="wp-block-heading">More About the Predictive Model</h2>



The model identified eight primary factors that predict treatment resistance, as reported by research participants. Each offers different dimensions of their depression.



<figure class="wp-block-image alignleft size-full is-resized"><img loading="lazy" decoding="async" width="275" height="252" src="http://35.88.189.111/wp-content/uploads/2025/10/depression.png" alt="" class="wp-image-34307" style="width:184px;height:auto"/></figure>



Participants reported on the different symptoms that persisted between the episodes of depression. They reported on how long each episode of depression lasted, and how many years they&#8217;d experienced these periodic episodes. Also included in the self-reported data were levels of stress, or whether they had recurring post-traumatic stress, and two critical factors that looked at more external stressors and life events. Also factored into the modeling was a participant&#8217;s age and whether they had suicidal thoughts. Finally, the model included the self-reported timing between episodes of depression, which was significant when the time between episodes was shorter.



Using these factors and advanced machine learning the researchers were able to accurately distinguish between those who were treatment-resistant and those who responded to treatment. An accurate way to identify if someone will or will not respond to treatment could translate into meaningful clinical benefits. It could mean the difference between waiting months for effective treatment instead of years.&nbsp;



<h2 class="wp-block-heading">More Personalized Depression Care</h2>



This research represents a crucial step toward more personalized mental health treatment and a move away from a &#8220;one-size-fits-all&#8221; approach to treatment of depression.&nbsp;



For the millions of people living with depression, this work represents a path toward precision care, shortening the time to effective treatment and improving quality of life.



The future of depression treatment lies not just in developing new medications, but in better understanding who needs what treatment when. This predictive model brings us measurably closer to that goal, promising a world where effective depression treatment is not a matter of luck, but of precision.



If you or someone you know is struggling with depression, please reach out to a mental health professional. The <a href="https://988lifeline.org/" target="_blank" rel="noreferrer noopener">National Suicide Prevention Lifeline</a> (988) provides 24/7 support for those in crisis.

Predicting Treatment-Resistant Depression Using the 23andMe Survey Data

Every year on the third Saturday in October, the world celebrates International Archaeology Day, recognizing the important contributions archaeological research makes to society. This year, to celebrate, we&#8217;re spotlighting one of our favorite archaeological mysteries in the <a href="https://blog.23andme.com/articles/23andmes-historic-matches" target="_blank" rel="noreferrer noopener">Historical Matches</a>SM feature—the skeletons of Roopkund Lake.



<h2 class="wp-block-heading" id="h-about-roopkund-lake">About Roopkund Lake</h2>



Roopkund Lake is a small glacial lake located over 5,000 meters (over 16,000 ft) above sea level in the Nanda Devi National Park, in the Indian Himalayas. In 1942, a forest ranger patrolling the park stumbled upon a chilling scene: hundreds of skeletal remains strewn around the lake. The site has captivated researchers and locals alike ever since.



The mystery of who these individuals were, how they died, and why they were in such a remote and inhospitable location has sparked decades of speculation. Some early researchers proposed that the remains belonged to an army that had lost its way in the mountains, while others suggested they might have been traders following a trans-Himalayan route that had since vanished. A few archaeologists posited that they were pilgrims traveling to nearby shrines, possibly part of the ancient Nanda Devi Raj Jat, a religious procession spanning ~290 kilometers (~180 miles) that is still undertaken in the region every 12 years.



The identification of women and children among the dead, however, made some of the proposed explanations less plausible–especially the claim that they may have been members of an army. Without weapons, trade goods, or written records, no single theory could fully account for the diversity and composition of the group. Local folklore offered its own interpretation: a king, his family, and attendants on a pilgrimage to honor the mountain goddess Nanda Devi had violated sacred protocol and were struck down by a deadly hailstorm in divine retribution.



<h2 class="wp-block-heading" id="h-an-exciting-23andme-connection">An exciting 23andMe connection</h2>



<a href="https://pubmed.ncbi.nlm.nih.gov/31431628/" target="_blank" rel="noreferrer noopener">In 2019</a>, scientists sequenced the genomes of 38 individuals from Roopkund Lake in an effort to better understand the origins of the mysterious remains. But instead of resolving this longstanding mystery, their findings uncovered an even more complex puzzle. 



So what makes this story one of 23andMe’s favorite archaeological mysteries? That 2019 research study was actually led by our very own Dr. Éadaoin Harney—a Scientist on the Population Genetics R&amp;D Team and 23andMe’s “resident ancient DNA expert.” She worked on this study during her PhD at Harvard University where she was a member of Prof. David Reich’s ancient DNA laboratories–one of the largest ancient DNA research laboratories in the world.



“When I first started working with the Roopkund ancient DNA data, I thought that genetics would be a simple and straightforward way to finally help solve the mystery of who they were,” said Dr. Harney. But she was in for a big surprise! “The first hint that this wasn’t going to be as simple as I initially thought was when we discovered how ancestrally diverse the Roopkund individuals were. Then we learned that they didn’t all die at the same time, as had previously been believed. Instead radiocarbon dates generated from the bones spanned over 1,000 years.”



<h2 class="wp-block-heading" id="h-how-dna-adds-to-the-mystery">How DNA adds to the mystery</h2>



The 2019 genetic analysis showed that the individuals fell into three distinct genetic groups, with ancestries from across the globe.



The largest group (which we’ll refer to as Roopkund A) consisted of 23 individuals who died between the 7th and 10th centuries CE, likely during multiple distinct events. Genetically, all appeared South Asian, but with remarkably diverse ancestries–each individual appeared most closely related to different present-day South Asian populations. This finding suggests that they may have traveled to the lake from multiple locations across the subcontinent. Although the exact purpose of their journey to Roopkund Lake remains uncertain, some researchers speculate that they may have been early participants in the Nanda Devi Raj Jat, a traditional pilgrimage that still passes by the lake every 12 years.



The other two groups were even more surprising. One group (Roopkund B) consisted of 14 individuals whose DNA connected them to present-day populations from the eastern Mediterranean—particularly populations in Greece and neighboring regions. The third group (Roopkund C) was represented by a single individual with genetic ancestry most similar to Southeast Asian populations. Radiocarbon dating revealed that these individuals likely died in a single event some time between the 17th and 20th centuries. Why people with ancestry from such distant regions were traveling together in one of the most remote parts of the Himalayas remains a mystery to this day.



Dr. Harney joined 23andMe in 2020 with the goal of creating an approach to identify direct genetic connections between historical and living people. She and her colleagues on the Population Genetics R&amp;D Team succeeded! This technology was first described in their <a href="https://pmc.ncbi.nlm.nih.gov/articles/PMC10958645/" target="_blank" rel="noreferrer noopener">2023 study of African Americans from Catoctin Furnace</a>, which was published in (and featured on the cover of) Science. She then helped spearhead the creation of the 23andMe Historical Matches feature, enabling customers to learn how they connect to different historical and ancient individuals.



Over the last five years, one of her secret ambitions was to use this technology to try and finally solve the mystery of the Roopkund individuals&#8217; identities. Could identifying any close genetic relatives of the Roopkund individuals in the 23andMe genetic database help us learn about their identities and answer what brought them to Roopkund?



<h2 class="wp-block-heading" id="h-did-we-solve-the-mystery">Did we solve the mystery?</h2>



We compared the Roopkund individuals to over 11 million research consenting participants in the 23andMe genetic database. While we were hoping this analysis would reveal a number of close genetic relatives, unfortunately, the mystery of Roopkund Lake lives on.



We found that only about 1,240 research participants—less than 0.011% of the individuals included in our analysis—share any sort of genetic connection to the Roopkund individuals. And of those participants, we can count the number of individuals who share over 30 cM of DNA (what we label a “significant genetic connection” in the Historical Matches feature) on just one hand. In fact, we found so few &#8220;significant relatives” that the chances any of those connections trace back to a recent shared common ancestor on a genealogical family tree are extremely slim.



(Although if you happen to be one of those lucky individuals who sees a “significant connection” listed to one of the Roopkund individuals in your 23andMe report, please <a href="https://customercare.23andme.com/hc/en-us/requests/new" target="_blank" rel="noreferrer noopener">reach out to us</a>, as we’d love to learn more!)



<h2 class="wp-block-heading" id="h-what-else-did-we-discover">What else did we discover?</h2>



So, we didn’t solve the mystery of who the Roopkund individuals were, but we did gather fascinating data about their connections to the present day.



First, here is a breakdown of the 17 Roopkund individuals whose DNA was well preserved enough to include in our analyses:



<ul class="wp-block-list">
<li>8 from Roopkund A (South Asian ancestry)</li>



<li>8 from Roopkund B (Eastern Mediterranean ancestry)</li>



<li>1 from Roopkund C (Southeast Asian ancestry)</li>
</ul>



As we mentioned, about 1,240 23andMe research participants shared a genetic connection to the Roopkund individuals. The figure below shows the number of matches each Roopkund group received and highlights the amount of DNA shared. As you can see, the vast majority of the connections we discovered involve less than 20 cM of DNA, meaning that they likely trace back to a shared common ancestor who lived long before any of the Roopkund individuals.



<figure class="wp-block-image size-full is-resized"><img loading="lazy" decoding="async" width="411" height="252" src="http://35.88.189.111/wp-content/uploads/2025/10/image-3.png" alt="" class="wp-image-34359" style="width:625px;height:auto" srcset="https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/10/image-3.png 411w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/10/image-3-300x184.png 300w" sizes="auto, (max-width: 411px) 100vw, 411px" /><figcaption class="wp-element-caption">This figure shows the distribution of total shared DNA that we detected between 23andMe research participants and each of the Roopkund groups (A, B and C). It shows that the vast majority of the connections we identified are to individuals in the Roopkund B group, and the DNA segments they share are shorter than 15 cM. In order to protect participant privacy, all counts less than or equal to 5 are masked and appear equal to 5. </figcaption></figure>



Of those who share a genetic connection, the majority (~1,160) shared a connection to one or more individuals in the Roopkund B group—the one with Eastern Mediterranean-related ancestry. This didn&#8217;t surprise us, since the majority of 23andMe research participants have European ancestry, making them more likely to be related to the Roopkund B individuals.



In addition to occurring more frequently, the Roopkund B individuals also shared some of the strongest genetic connections to 23andMe research participants, as shown in the figure below which depicts the maximum amount of DNA that each Roopkund individual shared with a research participant.



<figure class="wp-block-image size-full"><img loading="lazy" decoding="async" width="643" height="448" src="http://35.88.189.111/wp-content/uploads/2025/10/image-4.png" alt="" class="wp-image-34360" srcset="https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/10/image-4.png 643w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/10/image-4-300x209.png 300w" sizes="auto, (max-width: 643px) 100vw, 643px" /><figcaption class="wp-element-caption">This figure shows the maximum amount of shared DNA that we detected between 23andMe research participants and each of the Roopkund individuals. The individuals are arranged along the x-axis by when they lived, as measured by radiocarbon dating. We masked this result for Roopkund individuals who shared DNA with 5 or fewer 23andMe research participants in order to protect participant privacy, and reported maximum DNA sharing as equal to 0.</figcaption></figure>



We decided to see what Genetic Groups the Roopkund individuals could be connected to, using the same approach that we use to connect customers to these Genetic Groups.&nbsp;&nbsp;&nbsp;



Many of the Roopkund B individuals received matches to Genetic Groups in south eastern Europe, with the strongest connections to groups in Greece and Crete–exactly mirroring the findings of the original study!



<figure class="wp-block-image size-large is-resized"><img loading="lazy" decoding="async" width="1024" height="849" src="http://35.88.189.111/wp-content/uploads/2025/10/roopkund_b_2-1024x849.png" alt="" class="wp-image-34352" style="width:575px" srcset="https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/10/roopkund_b_2-1024x849.png 1024w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/10/roopkund_b_2-300x249.png 300w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/10/roopkund_b_2-768x636.png 768w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/10/roopkund_b_2-880x729.png 880w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/10/roopkund_b_2-1180x978.png 1180w" sizes="auto, (max-width: 1024px) 100vw, 1024px" /><figcaption class="wp-element-caption">This map shows the location of the different Genetic Groups that we compared the Roopkund B individuals to. Groups shown in darker colors shared the strongest genetic matches to one or more of the Roopkund B individuals.</figcaption></figure>



Since the Roopkund A and Roopkund C individuals shared far fewer genetic connections to 23andMe research participants, it was hard to localize their ancestry in the same way. But we were able to connect the Roopkund C individual to a single Genetic Group, located in China. This finding is generally consistent with the original study, where this individual exhibited connections to populations in East and Southeast Asia.&nbsp;



<figure class="wp-block-image size-large is-resized"><img loading="lazy" decoding="async" width="1024" height="874" src="http://35.88.189.111/wp-content/uploads/2025/10/roopkund_c_2-1024x874.png" alt="" class="wp-image-34353" style="width:592px;height:auto" srcset="https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/10/roopkund_c_2-1024x874.png 1024w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/10/roopkund_c_2-300x256.png 300w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/10/roopkund_c_2-768x655.png 768w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/10/roopkund_c_2-880x751.png 880w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/10/roopkund_c_2-1180x1007.png 1180w" sizes="auto, (max-width: 1024px) 100vw, 1024px" /><figcaption class="wp-element-caption">This map shows the location of the different Genetic Groups that we compared the Roopkund C individual to. Groups shown in darker colors shared the strongest genetic matches to the Roopkund C individual.</figcaption></figure>



We couldn’t connect the Roopkund A individuals to any of the Genetic Groups that we have identified. That doesn’t mean they aren’t genetically related to any of these groups. Instead it is likely just because the original research team was only able to sequence a small amount of DNA from these individuals, making it harder to connect them to research participants in the 23andMe database.&nbsp;



<h2 class="wp-block-heading" id="h-what-s-next">What’s Next?</h2>



So for now, all we can say is that the mystery of Roopkund Lake continues. But we promise this archaeological site is one that is close to our hearts. If we have any updates in the future, we’ll be sure to let you know.



<h2 class="wp-block-heading" id="h-learn-more">Learn more</h2>



Want to see if you share a genetic connection with any of the individuals who died at Roopkund Lake—or hundreds of other historical people? The Historical Matches feature is available to <a href="https://www.23andme.com/membership/" target="_blank" rel="noreferrer noopener">23andMe+ Premium</a>™ members.



And if you are interested in finding ways to celebrate International Archaeology Day, check out organizations like the Archaeological Institute of America, which has an exciting <a href="https://www.archaeological.org/events/category/international-archaeology-day/list/" target="_blank" rel="noreferrer noopener">calendar of Archaeology-related events</a>.

New Historical Matches Could Connect You to the Mysterious Skeletons of Roopkund Lake

<div class="wp-block-group is-nowrap is-layout-flex wp-container-core-group-is-layout-6c531013 wp-block-group-is-layout-flex">
This October, for Breast Cancer Awareness Month, we will be sharing some of the latest research on this important topic.
</div>



What if the same genetic factors that put you at higher risk for developing cancer could potentially increase the chances you&#8217;d survive longer if you do get cancer? This counterintuitive possibility is exactly what researchers discovered in a groundbreaking collaboration between the 23andMe Research Institute and the Dana-Farber Cancer Institute.



<h2 class="wp-block-heading" id="h-understanding-cancer-risk-and-polygenic-scores">Understanding cancer risk and polygenic scores</h2>



Like most common diseases, cancer is multifactorial – it&#8217;s caused by a combination of genetic factors and non-genetic factors like environmental exposures and lifestyle. Polygenic risk scores are tools that can estimate an individual&#8217;s inherited genetic risk of developing many common conditions, such as cancers.&nbsp;



A <a href="https://pubmed.ncbi.nlm.nih.gov/40877800/" target="_blank" rel="noreferrer noopener">recent study</a> conducted at the Dana-Farber Cancer Institute investigated whether  polygenic risk scores may be associated not just with risk of disease, but with clinical outcomes. The study analyzed nearly 24,000 cancer patients to ask whether having a high <a href="https://blog.23andme.com/articles/three-new-prs-cancer-reports" target="_blank" rel="noreferrer noopener">polygenic risk score, predicting a high likelihood of cancer</a>, also could tell you anything about the prognosis for a person who does go on to develop cancer.



In collaboration with 23andMe, researchers looked at polygenic risk scores for more than 200 diseases to see if any could also predict the prognosis of six common cancer types: non-small cell lung cancer, colorectal cancer, breast carcinoma, glioma, ovarian cancer, and prostate cancer.&nbsp;



<h2 class="wp-block-heading" id="h-an-unexpected-finding">An unexpected finding</h2>



Surprisingly, they found that among breast cancer patients, those with high polygenic risk scores for breast cancer actually showed longer average survival times than those with low scores. This finding held up even when accounting for other factors like a patient&#8217;s age, treatment, or different kinds of tumors.



Why might this be the case?&nbsp;



Cancer-causing genetic changes come in two types: those you&#8217;re born with (germline mutations) that appear in every cell, and those that develop over time in specific tissues (somatic mutations) due to factors like smoking or aging. Polygenic risk scores measure only germline mutations.



The researcher&#8217;s results raise the possibility that tumors driven more by germline mutations — and corresponding high polygenic risk scores — may tend to be less aggressive compared to tumors that are more driven by somatic mutations.&nbsp;



<h2 class="wp-block-heading" id="h-what-comes-next">What comes next</h2>



While these results are statistically robust, they&#8217;ll need to be confirmed in other studies before changing how doctors might treat cancer patients. With additional investigation, these findings could eventually help doctors provide more personalized prognoses and potentially identify patients who might benefit from different treatment approaches based on their genetic risk profiles.

Study Reveals an Unexpected Link Between Genetic Cancer Risk Scores and Survival

This update is currently available to all eligible customers on the latest, V5, genotyping chip. 



The 23andMe Ancestry Team has been working hard on <a href="https://blog.23andme.com/articles/a-major-update-to-ancestry-composition-is-coming-soon" target="_blank" rel="noreferrer noopener">a major update to the Ancestry Composition report</a>, and results are now available! Our goal is to provide the most accurate and meaningful genetic ancestry results in the industry. We ground our models in rigorous science, guided by established population genetics research, to ensure your results are consistent, reliable, and can help guide your personal journey of discovery.



<h2 class="wp-block-heading" id="h-what-changes-you-ll-see">What changes you&#8217;ll see</h2>



<ul class="wp-block-list">
<li>New granularity in your ancestry percentages: 33 new populations in Europe and 6 in the Americas to explore. Plus we&#8217;ve updated our algorithm to eliminate “Broadly” and “Unassigned” categories in the default results view.&nbsp;</li>



<li>More accurate results: A new state-of-the-art DNA phasing pipeline reduces errors and gives a more accurate estimate of your percentages, even if your ancestry isn&#8217;t from Europe or the Americas.&nbsp;</li>



<li>New features: A new “Version History” section lets you compare your new results to your previous result, and <a href="https://www.23andme.com/membership/" target="_blank" rel="noreferrer noopener">23andMe+ Premium</a>™ members can also access all previous versions of their results at different confidence thresholds.</li>
</ul>



This update powers your Ancestry Composition, Ancestry Timeline, Parental Inheritance, DNA Painting, and more.



<h2 class="wp-block-heading" id="h-our-focus-for-this-update">Our focus for this update</h2>



For this update we focused on improving the entire Ancestry Composition pipeline integrating the latest research. Throughout the rounds of development we look at two major metrics: precision and recall. Precision lets us know how often we correctly predict that a piece of DNA is from a specific population. Recall tells us how much DNA from a specific population we can correctly identify. Working to maximize both precision and recall is critical to making Ancestry Composition and other ancestry features as accurate as possible.



<figure class="wp-block-image alignleft size-full is-resized"><img loading="lazy" decoding="async" width="366" height="368" src="http://35.88.189.111/wp-content/uploads/2025/09/AC78_wheel.png" alt="" class="wp-image-34276" style="width:170px;height:auto" srcset="https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/09/AC78_wheel.png 366w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/09/AC78_wheel-298x300.png 298w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/09/AC78_wheel-150x150.png 150w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/09/AC78_wheel-271x271.png 271w" sizes="auto, (max-width: 366px) 100vw, 366px" /></figure>



The final models in this update had good precision and recall across the new populations, ensuring the accuracy of the ancestry breakdown predictions while also expanding the specificity and granularity of the populations. One example of the improvements gained by this update is the reduced amount of North Asian ancestry predicted for some Indigenous North American customers. You can learn more about the development process and see precision and recall metrics for each population in the <a href="https://www.23andme.com/ancestry-composition-guide/" target="_blank" rel="noreferrer noopener">Ancestry Composition Guide</a>.



While this update focused on increasing granularity in Europe and the Americas, customers from other parts of the world will still benefit thanks to the improvements to the science and the removal of broadly and unassigned ancestry.



<a href="https://you.23andme.com/" target="_blank" rel="noreferrer noopener">Sign in</a> and check out your new results.&nbsp;



Not yet a 23andMe member? Learn more about what <a href="https://www.23andme.com/compare-dna-tests/" target="_blank" rel="noreferrer noopener">23andMe has to offer</a>.



<h2 class="wp-block-heading" id="h-some-questions-you-might-be-wondering-about">Some questions you might be wondering about</h2>



Why are certain populations combined?



To define the 78 Ancestry Composition populations, we analyzed the reference datasets, chose candidate populations that appeared to cluster together, and then evaluated whether we can distinguish those groups in practice. Some populations tend to cluster on their own, but most country-level populations overlap to some degree. In these cases, we experiment with different groupings of country-level populations to find combinations that we can distinguish with high confidence. Check out the <a href="https://www.23andme.com/ancestry-composition-guide/" target="_blank" rel="noreferrer noopener">Ancestry Composition Guide</a> to learn more.



Does this mean that the people in those groups are the same? No. Each group has its own history, culture, and often different languages. These groupings are a reflection of our current genetic understanding and scientific methods, not a statement about cultural identity.



Does this mean DNA that is assigned to these populations is from all groups? Not necessarily. For example, DNA assigned to the Belarusian, Polish &amp; Ukrainian group might mean your ancestors were from one, two, or all three of those country-level populations. Sometimes other information from your DNA, such as your Genetic Groups, might help you identify more specific locations your ancestors may have come from.&nbsp;



Why are some reference panels smaller than before?



A reference panel, or a reference population or reference dataset, is a collection of DNA samples from people with some common connection. We compare your DNA to these reference panels to determine which ancestry most closely corresponds to your DNA. We often use 23andMe research participants who tell us they have four grandparents all born in the same country for reference panels.



However, sometimes when we look at the ancestry prediction for individuals in a reference panel for a specific population a few individuals don&#8217;t end up being predicted to have a reasonably large percentage of their DNA from that population. These individuals are considered outliers. As part of this update we systematically reviewed our reference panels around the world to remove these outliers. But don&#8217;t worry; even though some reference panels might be smaller, we still check that the models perform as well as (or better than) before for people with ancestry from these regions.&nbsp;



Why is there no Indigenous Caribbean population?



To define a new ancestry population we need reference panels made up of individuals who have deep genetic roots from one place. However, many individuals from the Caribbean are highly admixed (“admixture” refers to places where there was mixing of previously separate populations). This makes it incredibly difficult to identify a sufficient number of individuals with primarily indigenous DNA from the Caribbean. The reference panels for the new Indigenous American populations are almost entirely unadmixed, which is why we are able to provide ancestry percentages for these populations.&nbsp;



<figure class="wp-block-image alignright size-large is-resized"><img loading="lazy" decoding="async" width="1024" height="502" src="http://35.88.189.111/wp-content/uploads/2019/08/avg_ancestry_caribbean-1024x502.png" alt="" class="wp-image-27359" style="width:371px;height:auto" srcset="https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2019/08/avg_ancestry_caribbean-1024x502.png 1024w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2019/08/avg_ancestry_caribbean-300x147.png 300w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2019/08/avg_ancestry_caribbean-768x376.png 768w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2019/08/avg_ancestry_caribbean-880x431.png 880w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2019/08/avg_ancestry_caribbean-1180x578.png 1180w" sizes="auto, (max-width: 1024px) 100vw, 1024px" /></figure>



So where does Indigenous Caribbean ancestry show up? We tend to see that Indigenous American ancestry in individuals from the Caribbean is spread among several of the new Indigenous American populations (especially North American, Southern Mesoamerican, Central Andean &amp; Amazonian, and Northern Andean).



Does this mean Indigenous Caribbean ancestors came from those places? Not necessarily. It simply means that of the options available today, those populations are the closest genetic match.&nbsp;



Why weren&#8217;t other parts of the world updated?



While we would love to be able to make major updates around the world more frequently, each new population requires new reference data and major updates in the prediction models. Throughout the years we have increased the number of populations across the rest of the world; however, we have not updated the populations in Europe since 2012. This update was an important opportunity to provide more detail in Europe and the Americas.



We will continue to work towards providing more specificity and granularity around the world in your ancestry percentages as well as Genetic Groups (keep an eye out over the next few months for new Genetic Groups in Africa), <a href="https://blog.23andme.com/articles/23andmes-historic-matches" target="_blank" rel="noreferrer noopener">Historical Matches</a>SM, and other features.



Why did the colors change?



Adding 39 new colors to the color palette was quite the task for the 23andMe Design Team. The team took this opportunity to think about the colors holistically, coming up with a new system that provides a gradient across the world, allowing for nearby populations that are closer together geographically to be represented by more similar colors, while at the same time providing a system that can work for more populations in the future.



Who will get this update?



All customers genotyped on the current (V5) chip and with access to the ancestry service will see this update. A genotyping chip (or array) tests for a fixed set of genetic variants (SNPs) across the genome. Different chip versions (V1, V2, V3, V4, V5, etc.) test for different sets of SNPs. More recent chips often include better coverage for certain populations, recently discovered variants, or better genetic markers that help improve ancestry?composition algorithms or detect health?associated variants.



Ancestry Composition is trained on specific genotyping chip versions, and these latest models were only trained on the latest chip version. The models are incompatible with data from older genotyping chips, as older chips don’t include most of the genetic markers used by these new ancestry models. More recent chip versions are also designed with better coverage for diverse populations. If you&#8217;re on an older chip version (or not sure which chip version you have) learn about chip upgrades <a href="https://customercare.23andme.com/hc/en-us/articles/360025014494-How-Do-I-Upgrade-My-Genotyping-Chip" target="_blank" rel="noreferrer noopener">here</a>.



What happens if my family deleted data and I want to connect with them?



When you connect with a biological parent through Your Connections, we use the additional information we learn from your parents&#8217; DNA to improve the resolution of your Ancestry Composition results. You will also be able to see the proportions of each ancestry that you inherited from each parent in the Parental Inheritance section in your Ancestry Composition report. If a family member has deleted their account they will need to purchase a new kit and create a new account before you can connect with them.

It’s Finally Here: A New Version of Ancestry Composition

Obsessive-compulsive disorder (OCD) is a complex and often debilitating condition that affects up to three percent of people, but the biological basis of the disorder has remained largely elusive. While we’ve known that genetics play a role, previous genetic studies have been limited by their relatively small sample size and have only identified a few of the specific genetic variants involved.



But that is now changing.



<a href="https://pubmed.ncbi.nlm.nih.gov/40360802/" target="_blank" rel="noreferrer noopener">In a recent study</a>, the largest of its kind ever conducted for OCD, researchers identified dozens of genetic variants associated with the disorder, offering unprecedented insight into its underlying biology.



<h2 class="wp-block-heading" id="h-the-power-of-numbers">The Power of Numbers</h2>



For complex conditions like OCD, genetic discovery is a numbers game. To find the subtle genetic variations that contribute to risk, scientists need to compare the DNA of vast numbers of people with and without the condition. This is where the research model of the 23andMe Research Institute makes a world of difference.



<figure class="wp-block-image alignright size-full is-resized"><img loading="lazy" decoding="async" width="600" height="600" src="http://35.88.189.111/wp-content/uploads/2017/05/your_dna_family.png" alt="" class="wp-image-25345" style="width:141px;height:auto" srcset="https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2017/05/your_dna_family.png 600w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2017/05/your_dna_family-150x150.png 150w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2017/05/your_dna_family-300x300.png 300w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2017/05/your_dna_family-271x271.png 271w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2017/05/your_dna_family-372x372.png 372w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2017/05/your_dna_family-574x574.png 574w" sizes="auto, (max-width: 600px) 100vw, 600px" /></figure>



This study combined data from 28 different cohorts. The result was a dataset of incredible scale, including 53,660 individuals with OCD and more than 2 million controls. Consented 23andMe research participants made up about half of the entire cohort in this study. This immense contribution, made possible by those who choose to participate in research, was critical to achieving the statistical power needed to make these new discoveries.



<h2 class="wp-block-heading" id="h-what-the-study-found">What the Study Found</h2>



By scanning the genomes of millions of individuals, the researchers identified 30 independent genetic variants that were significantly associated with OCD. Of these 30 genetic variants, half are entirely new discoveries, while the others confirm and strengthen findings from previous, smaller studies. Researchers mapped these genetic variants to 25 genes that are likely impacted by those variants.



<h3 class="wp-block-heading" id="h-zeroing-in-on-the-brain">Zeroing In on the Brain</h3>



Identifying the genes is just the first step. The next question is: where in the body do these genes do their work?



<figure class="wp-block-image alignleft size-full is-resized"><img loading="lazy" decoding="async" width="438" height="458" src="http://35.88.189.111/wp-content/uploads/2015/06/Brain-Logo.jpg" alt="Brain Logo" class="wp-image-22635" style="width:157px;height:auto" srcset="https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2015/06/Brain-Logo.jpg 438w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2015/06/Brain-Logo-287x300.jpg 287w" sizes="auto, (max-width: 438px) 100vw, 438px" /></figure>



To find out, the researchers performed tissue and single-cell enrichment analyses. The results were striking. The genetic signals for OCD were highly enriched in six different types of human brain tissue. In contrast, there was no enrichment found in tissues outside the brain.



The study drilled down even further, pinpointing specific cell types and found that these genes are at work in the same cells identified by neuroimaging and deep brain stimulation studies of OCD. By independently identifying these precise brain regions and cell types through genetics, this study provides additional supporting evidence that these genes and neurons play a direct role in the biology of OCD.



<h3 class="wp-block-heading" id="h-shared-genetics">Shared Genetics</h3>



The study also investigated the genetic relationship between OCD and other psychiatric and behavioral conditions. The researchers found statistically significant positive genetic correlations between OCD and a range of other disorders, including anxiety, depression, anorexia nervosa, and Tourette syndrome



This finding reinforces a growing body of evidence that many psychiatric conditions, while appearing different on the surface, are likely to share some underlying genetic susceptibility factors. Understanding this genetic overlap may be key to understanding mental health as a whole.



<h2 class="wp-block-heading" id="h-a-foundation-for-the-future">A Foundation for the Future</h2>



This study represents a pivotal moment for OCD research. By dramatically expanding the list of known genetic variants associated with OCD and grounding them in the specific biology of the brain, this work opens doors for researchers to explore the precise mechanisms by which these genes influence brain circuits and contribute to OCD symptoms.



Ultimately, these findings may be a critical step toward developing novel and more effective treatments for a disorder that has long been misunderstood.



And once again, we want to extend our deepest gratitude to 23andMe research participants. Your contribution to this landmark study has advanced our understanding of OCD and paved the way for a healthier future.

A Major Leap Forward in Understanding the Genetics of OCD

For many people, sniffling, sneezing, and rubbing itchy eyes is a rite of spring.
Pollen wafting through the air from budding trees, grasses, and flowers during spring triggers allergy attacks for millions of people worldwide. <a href="https://www.pnas.org/content/118/7/e2013284118">A recent study</a> indicated that climate change might be making the situation even worse for some due to the lengthening of the pollen season in North America.
Susceptibility to allergies — not just from pollen but also to things such as insect bites, dander from dogs and cats, or mold — is in part genetic. One&#8217;s environment also plays an important role in developing allergies. One silver lining of the last year is that mask-wearing during the pandemic appears to help lessen allergy symptoms in some, according to <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7467086/">recent research </a>done in Israel.

	<figure class="wp-block-image size-large is-style-default"><img loading="lazy" decoding="async" width="1024" height="678" src="https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2018/05/Sneeze-1024x678.jpg" alt="" class="wp-image-26180" srcset="https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2018/05/Sneeze-1024x678.jpg 1024w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2018/05/Sneeze-300x198.jpg 300w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2018/05/Sneeze-768x508.jpg 768w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2018/05/Sneeze-880x582.jpg 880w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2018/05/Sneeze-1180x781.jpg 1180w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2018/05/Sneeze.jpg 1259w" sizes="auto, (max-width: 1024px) 100vw, 1024px" /></figure>
	
<h6>Researching the Genetics</h6>
Allergic reactions themselves happen when a hypersensitive immune system mistakes a normally harmless substance for a harmful one. When the immune system detects these so-called allergens, it triggers an immune response meant to protect the body. Research indicates that <a href="https://pubmed.ncbi.nlm.nih.gov/16083793/">about half</a> of those living in the U.S. are sensitive to at least one common allergen. While most allergic reactions are mild, some contribute to asthma or eczema and can be very serious and even life-threatening.
23andMe scientists and our collaborators have identified many genetic variants associated with allergies over the years. We also published studies on the genetic <a href="https://www.nature.com/articles/s41588-018-0157-1">pathways for allergic rhinitis</a>, genetic associations between <a href="https://www.nature.com/articles/ng.3985">allergies, eczema, and asthma</a>, and the age of <a href="https://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.1008725">onset</a>. That work allows us to understand not just the underlying causes better, but also offers researchers potential new targets for treatments. 

	<figure class="wp-block-image size-large is-style-default"><img loading="lazy" decoding="async" width="1024" height="264" src="https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2021/04/Dog-Cat-.001-1024x264.jpeg" alt="" class="wp-image-28847" srcset="https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2021/04/Dog-Cat-.001-1024x264.jpeg 1024w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2021/04/Dog-Cat-.001-300x77.jpeg 300w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2021/04/Dog-Cat-.001-768x198.jpeg 768w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2021/04/Dog-Cat-.001-880x227.jpeg 880w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2021/04/Dog-Cat-.001.jpeg 1055w" sizes="auto, (max-width: 1024px) 100vw, 1024px" /></figure>
	
<h6>Cats and Dogs</h6>
People with allergies to dogs or cats react to the proteins found in animals’ saliva, their skin cells (also called &#8220;dander&#8221;), or urine. Those allergens trigger a response of the body&#8217;s immune system leading to sneezing, runny nose, watery eyes, and itchy skin. In some cases, people with dog or cat allergies may experience asthma symptoms, such as difficulty breathing or wheezing. For people with dog or cat allergies, lifestyle modifications and other treatments, including medications, can help ease symptoms.
It is estimated that <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5809771/">10 percent-to-20 percent of people</a> are allergic to dogs or cats worldwide.
For 23andMe customers who want to explore a little deeper into their genetic likelihood of having certain allergies, we offer <a href="https://www.23andme.com/membership">23andMe+</a>, an annual membership with 10+ exclusive reports and features delivered to you throughout the year‡.
Those reports are powered by 23andMe research and include new Wellness reports on cat allergies and on dog allergies. Both use statistical modeling that utilizes thousands of genetic variants, as well as a customer&#8217;s ethnicity and sex to estimate the likelihood of developing a dog or cat allergy.
<h6>Pets and Pollen</h6>
For those with pet allergies, preventing reactions isn&#8217;t as simple as you&#8217;d think. It&#8217;s not just about avoiding dogs and cats because pet allergens can travel easily through the air. They can stick to clothing and other surfaces, quickly spreading from place to place. In the United States, about half of households <a href="https://pubmed.ncbi.nlm.nih.gov/28694047/">own a cat or a dog</a>. Yet, studies have shown that detectable levels of pet allergens can be found in almost all homes, even ones that don&#8217;t own pets. High levels of pet allergens have also been found in public places like schools, offices, buses, and trains. To prevent reactions, experts recommend washing hands and clothes frequently.
Allergies to cats and dogs and allergies to pollens are alike in some ways. They are very similar in how they make their way into the body, what symptoms they cause, and how you treat them, for instance.
<h6>Finding Out More</h6>
Find out more about 23andMe&#8217;s Health + Ancestry Service or 23andMe+ membership <a href="https://www.23andme.com/dna-health-ancestry?sub=ver2&amp;cabt=nao">here</a>.
‡10+ reports and features will be added annually from January to December.

	<figure class="wp-block-image size-large is-style-default"><img loading="lazy" decoding="async" width="1024" height="536" src="https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2021/04/1200x628-2-1024x536.png" alt="" class="wp-image-28846" srcset="https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2021/04/1200x628-2-1024x536.png 1024w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2021/04/1200x628-2-300x157.png 300w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2021/04/1200x628-2-768x402.png 768w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2021/04/1200x628-2-880x461.png 880w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2021/04/1200x628-2-1180x618.png 1180w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2021/04/1200x628-2.png 1200w" sizes="auto, (max-width: 1024px) 100vw, 1024px" /></figure>

23andMe+ new Cat and Dog Allergy report release

The Genetics of Allergies

Research shows that there really are &#8220;cat people&#8221; and &#8220;dog people.&#8221; Being one or the other is associated with differences in personality and well-being, according to new data analyzed by 23andMe.



<figure class="wp-block-image alignright size-medium"><img loading="lazy" decoding="async" width="300" height="200" src="http://35.88.189.111/wp-content/uploads/2022/09/GettyImages-1196356447-300x200.jpg" alt="" class="wp-image-30160" srcset="https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2022/09/GettyImages-1196356447-300x200.jpg 300w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2022/09/GettyImages-1196356447.jpg 724w" sizes="auto, (max-width: 300px) 100vw, 300px" /></figure>



While the data reveals a clear cat-dog divide, what is less clear is whether it reflects pre-existing differences or whether owning a dog or a cat contributes to those differences. In other words, does owning a dog or cat make you feel better, less stressed, or even improve your overall health? Does it influence how outgoing you are or how much you exercise?



<h2 class="wp-block-heading" id="h-seeking-solace">Seeking Solace</h2>



Those are interesting questions, especially now during this period of social isolation due to the pandemic. Since the start of stay-at-home orders, there has been a surge in pet adoptions in the United States. This surge has resulted in fewer pets to adopt and a so-called <a href="https://abc7news.com/national-christmas-puppy-shortage-adopting-for-holidays-demand-covid-pandemic-more-dogs-bay-area/6873566/">&#8220;puppy shortage&#8221;</a> just as the holidays approach.



The increased demand for cats and dogs also suggests that owning a pet offers the potential for companionship and solace during these stressful times for some people. That&#8217;s been true for ages. People have kept cats and dogs as companions for millennia. The bond with dogs goes back <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0022821">30,000 years</a>, while cats took a little longer to cozy up to humans, and that bond goes back 4,000 years. The domestication of cats and dogs benefited both humans and our canine and feline friends. Over time that relationship has evolved beyond merely catching rodents or guarding us by the campfire.



<h2 class="wp-block-heading" id="h-some-differences-between-cat-and-dog-owners">Some Differences Between Cat and Dog Owners</h2>



<div style="float: right; text-align: justified; width: 300px; background-color: #eee; padding: 15px; margin-left: 10px;">
<h6>Cat Owners</h6>
<code style="display: none;"> 
</code>
<ul>
<li>If you are married without kids, you’re more likely to own a cat.</li>
<li>Cat owners are a little more stressed than dog owners.</li>
<li>Cat owners are more likely to live in an urban setting than dog owners.</li>
<li>Women, particularly middle-aged women, are more likely to own a cat.</li>
<li>Cat owners are on average more highly educated.</li>
</ul>
<code style="display: none;"> 
</code>
</div>



For years, scientists have studied pet ownership and its correlation to differences in <a href="https://www.tandfonline.com/doi/abs/10.2752/175303710X12750451258850">personality</a> and health outcomes. There is some promising research on the <a href="https://www.nature.com/articles/s41598-019-44083-9#Abs1">heritability of dog ownership</a>. In addition to genetic factors, 23andMe&#8217;s data reveals that cat and dog ownership is a good barometer for health, personality, and even certain behaviors. We also saw differences between those who owned a cat versus a dog. (See sidebar for some of those clear differences in the data.)



For instance, our data showed that women, particularly middle-aged women, are more likely to own a cat than men. Also, if you are married but do not have children, you&#8217;re more likely to own a cat. And cat owners are a little more stressed than dog owners.



However, whether you own a dog or a cat also correlates with other things. Where you live, in a city or a more rural community, plays a role, such as your income and family status. Those demographic factors also affect your health and personality.



So what did we find?



<h2 class="wp-block-heading" id="h-pets-and-stress">Pets and Stress</h2>



<div style="float: right; text-align: justified; width: 300px; background-color: #eee; padding: 15px; margin-left: 10px;">
<h6>Dog Owners</h6>
<code style="display: none;"> 
</code>
<ul>
<li>Dog owners are more likely to be married with kids.</li>
<li>Dog owners get a lot more exercise than people who don’t own a dog, 14 percent more likely to exercise each week.</li>
<li>Dog owners are more extroverted than those who don’t own a dog.</li>
</ul>
<code style="display: none;"> 
</code>
</div>



Some of it was surprising, considering the surge in pet adoptions. 23andMe&#8217;s data — from more than 1.5 million customers who consented to participate in research — found an association between owning a cat or a dog and more stress, not less. We used a <a href="http://www.ucdenver.edu/academics/colleges/medicalschool/departments/Anesthesiology/Wellness/Documents/PerceivedStressScale.pdf">10-item Perceived Stress Scale</a> to compute a relative stress score. Our data, however, doesn&#8217;t show whether individuals get pets because they are already stressed or whether their stress comes from the added responsibilities of owning a pet. People with more stress may be more likely to own pets, and we do not have data to show whether owning a pet helps reduce that stress.



23andMe&#8217;s findings offer a slightly different take on other studies that <a href="https://www.cnbc.com/2020/03/20/pets-make-you-less-stressed-more-productive-and-healthy-amid-covid-19.html">associate lower stress with pet ownership</a>. But both cat and dog owners are more likely to be stressed, so we simply can’t say whether owning a pet helps to lower their stress.



Our data also highlighted some differences between cat owners and dog owners. For example, dog owners are more likely than cat owners to be married with kids, and they&#8217;re more likely to exercise each week. And dog owners are more extroverted than those who don&#8217;t own a dog.



While the dog versus cat divide may tell us something about personality traits and well-being, it&#8217;s not the complete picture. Some of those differences may have more to do with whether you live in a city or live in rural areas, which may have something to do with demographics.



<h2 class="wp-block-heading" id="h-urban-and-rural-divide">Urban and Rural Divide</h2>



Below is what we saw when we plotted some of this data on maps of the US. We found distinct regional differences between urban and rural communities. For example, we saw that customers in Alaska, which is mostly rural, are much more likely to own a dog than a cat. That’s likely because it’s too cold in Alaska for cats to be outside.



Simultaneously, being in a rural county doesn&#8217;t necessarily mean you&#8217;re more likely to be a dog owner. For instance, in similarly rural states in the Northeast, specifically in Maine, Vermont, and New Hampshire, customers are more likely to own a cat, which may be because cats are used for pest control.



So why do we ask these kinds of questions? What does owning a cat or a dog have to do with genetics or your health?



23andMe asks customers many questions, not just about their health and traits but also about seemingly unrelated things like their ability to do a cartwheel or curl their tongues. We ask these questions because they add layers to what we can learn about how the environment and genetics play a role in personality, well-being, and even health risks.



Customers who are participating in research can look at our <a href="https://you.23andme.com/p/394a5612ffeef442/research/">research overview here</a>. Not yet, a customer? You can <a href="https://www.23andme.com/compare-dna-tests/">Compare 23andMe products </a>or <a href="https://www.23andme.com/publications/">view our research publications</a> for more information.



&nbsp;

Cats and Dogs and People

<img loading="lazy" decoding="async" class="aligncenter size-medium wp-image-14825" src="https://blog-api.23andme.com/wp-content/uploads/2012/08/sled_dog-300x270.jpg" alt="" width="300" height="270" srcset="https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2012/08/sled_dog-300x270.jpg 300w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2012/08/sled_dog.jpg 365w" sizes="auto, (max-width: 300px) 100vw, 300px" />
Watching the Olympics, I am awed by the athleticism of the contestants: they compete with strength, skill and coordination that I could hardly dream of possessing. Certainly hard work and determination has played a role in each athlete’s story, but probably good genes have also contributed to their success.
And if <a href="https://www.23andme.com/topics/wellness/muscle-composition">genetics plays a role in human athletics</a>, it plays an even greater role in the success of animal athletes who are bred with performance in mind. Alaskan sled dogs were once just working dogs, but over the years have been carefully bred into a class of elite four-legged athletes.
Heather Huson and Elaine Ostrander from the National Institutes of Health (NIH) have lead a team of researchers from the NIH, the University of Alaska Fairbanks, and the University of California, Irvine to discover what makes a great dog athlete. Using the tools of modern genetics, they have addressed several questions. Are there genetic differences between sprinters and distance racers? Are there genetic differences between the “top dogs” and those that finish second? Their study&#8217;s findings were recently published in Mammaliam Genome. 

<div style="border: 1px solid #000; padding: 15px; font-style: italic; margin-bottom: 15px; width: 300px; float: right; margin-left: 15px; margin-top: 5px;">
<img loading="lazy" decoding="async" class="alignleft size-full wp-image-12163" style="float: left; margin-right: 15px;" src="https://blog-api.23andme.com/wp-content/uploads/2012/04/JRBgdIBXKIeVIdETJrxYIw_ttam_logo.jpg" alt="" width="24" height="40" /> To date, more than 150 genes have been linked to different aspects of physical performance in humans. One of the clearest associations is seen with a gene called ACTN3 that is normally turned on in a type of muscle fiber used for power-based sports. A single SNP can turn this gene off. 23andMe customers can see their muscle performance report to see if they are more genetically predisposed to be a sprinter or a endurance athlete.
Not yet a customer? Visit our <a href="https://www.23andme.com/store/cart/" target="_blank" rel="noopener noreferrer">store</a> or <a href="https://www.23andme.com/" target="_blank" rel="noopener noreferrer">learn more</a>.
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Alaskan sled dogs do not belong to one pure breed, but rather are a blend of several different purebred breeds that were combined to optimize for strength, speed, and trainability. Using genetic ancestry analysis, the team of researchers were able to confirm that sprinter and long distance racer dogs have significant differences in their breed blends. Using purebred Alaskan malamute, Siberian huskies, German shorthaired pointers, and borzois for reference, they established that sprinter dogs have a considerably larger dose of German shorthaired pointer ancestry and long-distance race dogs have more Alaskan malamute and Siberian husky ancestry. The authors suggest that dogs with more husky ancestry have more “mental toughness,” a necessity for the long hauls, whereas dogs with more pointer ancestry may be easier to train and are more eager to please and perform.
<div style="border: 1px solid #000; padding: 15px; font-style: italic; margin-bottom: 15px; width: 300px; float: left; margin-right: 15px; margin-top: 5px;">
Heather Huson: 
Scientist and Sled-Dog Racer 
Heather Huson, one of the leading researchers in this study, is a not only a scientist but also sled dog racing enthusiast.   Having qualified for the US Olympic team twice, she comes at this research with first hand knowledge. You can read more about Huson&#8217;s accomplishments &#8212; both at the bench and on the snow <a href="https://www.google.com/url?sa=t&amp;rct=j&amp;q=&amp;esrc=s&amp;source=web&amp;cd=1&amp;ved=0CGMQFjAA&amp;url=http%3A%2F%2Fwww.nih.gov%2Fcatalyst%2F2010%2F10.12.01%2Fcatalyst_v18i6.pdf&amp;ei=CvMfUM2HMa3SiAKKyoDIAg&amp;usg=AFQjCNHZ2VyBKqB3LnwDp-l2FVmil6rb3w">here (downloadable pdf)</a>.
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The researchers also did a genome-wide association study looking for genetic factors that influence heat tolerance in both sprinters and in long-distance racers.  They found that seven SNPs within one gene &#8212; MYH9 &#8212; were associated with the ability to perform well even in the heat. The dog days of summer perhaps don’t feel so hot for these lucky pooches. There is a similar version of this gene in humans, but more research is needed to determine whether variation in this gene affects human heat tolerance.
As we watch the Olympics in London this summer, we won’t see any four-legged friends on the winner’s podium. Nevertheless, Alaskan sled dogs are tremendous athletes, and genetic studies such as this one may offer insights into the amazing athletic talents of those who actually will be on the podium.
<img loading="lazy" decoding="async" class="aligncenter wp-image-14805 size-full" src="http://35.88.189.111/wp-content/uploads/2012/08/RaceDogImage.jpg" alt="" width="1981" height="1229" srcset="https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2012/08/RaceDogImage.jpg 1981w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2012/08/RaceDogImage-300x186.jpg 300w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2012/08/RaceDogImage-768x476.jpg 768w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2012/08/RaceDogImage-1024x635.jpg 1024w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2012/08/RaceDogImage-880x546.jpg 880w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2012/08/RaceDogImage-1180x732.jpg 1180w" sizes="auto, (max-width: 1981px) 100vw, 1981px" />
Alaskan sled dogs are a mixture of many purebred breeds. Generally speaking, the relative amounts of these different breeds varies according the type of racing &#8212; sprinter dogs tend to have more German shorthaired pointer ancestry and long-distance race dogs often have more Alaskan malamute and Siberian husky ancestry.

Canine Olympians

<img loading="lazy" decoding="async" class="alignnone wp-image-11835" src="https://blog-api.23andme.com/wp-content/uploads/2012/03/Shar-Pei-200x300.jpg" alt="" width="200" height="300" srcset="https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2012/03/Shar-Pei-200x300.jpg 200w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2012/03/Shar-Pei.jpg 283w" sizes="auto, (max-width: 200px) 100vw, 200px" />
<div style="width: 350px; background-color: #eeeeee; padding: 15px; margin-left: 10px; text-align: center; padding-bottom: 20px; font-size: 14pt;"><a href="http://www.nationalpuppyday.com/" target="_" rel="noopener">March 23rd is National Puppy Day!</a></div>
How did the Shar-Pei get his wrinkly skin? The question sounds like the beginning of one of Kipling’s “Just So” stories, but this and other questions were the subject of a recent genetics study. What gives some breeds their Lilliputian legs and others their lengthy limbs? Why do some breeds have docile dispositions and others tenacious temperaments?
The answers may lie in their doggy genes.
This study is not the first in canine genetics, and several genes have already been associated with size (IGFI), coat type (RSPO2, FGF5, KRT71), coat color (MITF, CBD103), short limbs (FGF4), snub noses (THBS2), and wrinkly skin (HAS2).
This new <a href="https://www.ncbi.nlm.nih.gov/pubmed/22022279" target="_" rel="noopener">study</a>, however, is different because the researchers developed a new DNA chip that analyzes the canine genome in higher resolution, and they used it to focus on behavioural traits as well as physical traits Altogether, the international group of scientists led by Matthew Webster &#8212; spanning France, Sweden, Finland, Spain, Denmark, and the United States &#8212; looked at the genetics of 509 dogs from 46 different breeds.

Although dogs were domesticated from wolves over 15,000 years ago, only in the last few centuries did dogs fan out into the distinct breeds we have today. Normally evolution is propelled by survival fitness; animals that survive better reproduce better, passing on their genetics and unique traits. &nbsp;In the case of dogs, however, the selective pressure was artificial. &nbsp;
Instead of fitness being based on increased survival in the wild, dogs were bred for size, disposition, and other traits that were deemed desirable by their owners.
<div style="float: left; width: 330px; height: 585px; border: 1px solid grey; padding-right: 10px; margin-right: 15px;">
<img loading="lazy" decoding="async" class=" wp-image-11834" src="https://blog-api.23andme.com/wp-content/uploads/2012/03/breedTree-300x291.gif" alt="" width="300" height="291" srcset="https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2012/03/breedTree-300x291.gif 300w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2012/03/breedTree-768x746.gif 768w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2012/03/breedTree-1024x994.gif 1024w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2012/03/breedTree-880x854.gif 880w" sizes="auto, (max-width: 300px) 100vw, 300px" />Figure 1 of the 2011 PLoS Genetics paper clusters 509 dogs based on their genetic similarity. In this figure, dogs that are genetically similar to each other are grouped together, and, not surprisingly, this grouping corresponds quite well with breed (dogs of the same breed are grouped together). Some breeds do cluster together (for instance, all the retrievers are clustered together, as are the all the spaniels), but the relatively long branches connecting dogs within the same breed and the relatively short branches connecting the different breeds together is consistent with breeds which originated from a common dog gene pool long ago and have remained quite distinct. Image from <a>Vaysse A, et al. PLoS Genet. (2011) vol. 7 iss. 10 pp. e1002316</a>.
</div>
This study by Webster and his colleagues suggests that the artificial evolution of dogs into their distinct breeds was very fast and very directed: even breeds within typically recognized subgroups (e.g. retrievers, spaniels, setters, and terriers) diverged from each other quite early. For example, Golden Retrievers and Labrador Retrievers are now quite genetically distinct after only a few centuries of breeding. A striking figure from their paper illustrates this concept.
Webster’s team further showed that some well-recognized dog traits can be traced to specific genetic variations, even across breeds.
For instance, they found a novel association between a region on chromosome 1 and curly tails across several breeds. In addition, ear morphology (pricked ears vs. dropped ears), size, and “boldness” of &nbsp;disposition (as measured by the Swedish Kennel Club) are all associated with genetic variation within one section of chromosome 10. They also found that the boldness trait was associated with the other two traits: all of the small, pricked-eared breeds studied were categorized as “bold” and all of the large, drop-eared breeds were categorized as “non-bold,” except for the Bernese Mountain Dog. &nbsp;
The researchers suggest that breeders may have optimized for certain ear morphologies, sizes, and/or degrees of boldness, thus putting selective pressure on this region of chromosome 10.
In addition to traits selected for in multiple breeds, the study also addressed a handful of more unusual traits that occur in only one or two breeds. Confirming earlier findings, Webster’s results suggest that the real story behind the Shar-Pei’s wrinkled skin may lie with mutations near the HAS2 gene on chromosome 13.
Likewise, their findings support the previously held hypothesis that the Dachshund’s short limbs may be due to mutations near the FGF4 gene on chromosome 18. These genetic regions are quite distinct from the corresponding regions in other breeds, representing a signal for active selection.
The delightfully friendly disposition of the Golden Retriever, the comically short gait of the Dachshund, and the adorably furrowed hide of the Shar-Pei are no accident. &nbsp;
These and the many other charming (and sometimes useful) attributes exhibited by modern breeds are the result of strong selective pressures, as this work illustrates. Dogs perfectly suit humans because they were bred to perfectly suit us. Of course the dog is “man’s best friend” &#8212; with such a pedigree, how could it be anything else?

How Did the Shar-Pei Get His Wrinkly Skin?

New genetic research may explain why Fluffy is so fluffy.
A study led by researchers at the National Human Genome Research Institute scanned 1,000 dogs from 80 breeds, looking for genes associated with different hair types: curly, wavy, straight, wiry, long, and any combination of these. Their results, published online last week in <a href="http://www.sciencemag.org/cgi/content/abstract/1177808" target="_blank" rel="noopener noreferrer">Science</a>, show that variations in just three genes account for nearly all types of coats worn by man’s best friend.
<h2>Dog Hair</h2>
The study found that purebred dogs with similar hair types were found to have similar variations in three particular genes, RSPO2, FGF5, and KRT71.
A particular variation in the RSPO2 gene was linked to wiry hair in a pattern that gives dogs a mustache and eyebrows, such as in a schnauzer.

A variation in the FGF5 gene was associated with long hair, whether silky or fluffy, like that in a Pomeranian. Variations in the KRT71 gene seem to affect the extent of hair curl in dogs like Irish water spaniels.
Previous studies have shown that the FGF5 and KRT71 genes also affect hair type in cats and mice, suggesting that their effects may be relevant to all mammals, including humans.
<h2>Short Hair, Long Hair, and In Between</h2>
Some dogs have all three variations identified by the researchers, including Portuguese water dogs, a breed you may have seen taking walks on the White House lawn.
Short-haired dogs like beagles, who don’t exhibit any different types of hair studied by the researchers, all seem to have the ancestral versions of the FGF5, RSPO2, and KRT71 genes. The study also found that wolves carry the non-mutated forms of these genes, suggesting that the different hair types evolved after the evolutionary split between the two canine subspecies.
Despite what we know about the genetics of hair type in dogs, little is known about what makes <a href="https://blog.23andme.com/articles/snpwatch-researchers-find-link-between-red-hair-and-avoiding-the-dentist/" target="_blank" rel="noopener noreferrer">human hair</a> straight, wavy, curly, frizzy, kinky, woolly, or helical. While hair type in dogs is easily classified, studying human hair is not as simple. Some scientists have suggested characterizing hair by curl ratios and other measurements, but our diverse biological background poses a challenge in classifying human hair types for research.
This study could help researchers better understand the genetics of hair type in humans. It has also unleashed new possibilities for human disease research because these three genes that affect dogs&#8217; coats also regulate many other processes in living organisms, allowing researchers to study how powerful genes interact.

Study Sniffs Out Genes Behind Dog Hair

On occasion, the Blog departs from its usual mission of bringing you the latest and greatest in human genetics news in order to report on particularly interesting discoveries in other species.
Many times these stories are about dogs and the reason is simple: dogs are awesome.
Well, there is more to it.
In addition to being faithful companions, dogs make great subjects for genetics research–the time between generations is much shorter in dogs than humans, they have multiple offspring per pregnancy and unlike in humans, it&#8217;s not unethical for scientists to decide which males and females breed together.
A luminary in the field of dog genetics is <a href="https://www.genome.gov/12513335" target="_blank" rel="noopener noreferrer">Elaine Ostrander</a>, chief of the Cancer Genetics Branch of the National Human Genome Research Institute.   Her lab uses dogs to study cancer susceptibility genes, but along the way they’ve made some fascinating discoveries about the incredible variation seen between the many breeds that make up the single species Canis lupus familiaris.
In 2007 Ostrander&#8217;s group showed that <a href="http://www.sciencedaily.com/releases/2007/04/070405144059.htm" target="_blank" rel="noopener noreferrer">small size in dogs</a>–think Chihuahuas and Pomeranians–can be traced to a single variant of the canine <a href="https://www.ncbi.nlm.nih.gov/pubmed/17412960?ordinalpos=16&amp;itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_DefaultReportPanel.Pubmed_RVDocSum" target="_blank" rel="noopener noreferrer">IGF-1</a> gene.
Now, in a paper published online this week in <a href="http://www.sciencemag.org/cgi/content/abstract/1173275" target="_blank" rel="noopener noreferrer">Science</a> Express, they have shown that a single evolutionary event is behind the short, curved legs characteristic of all those adorable dachshunds, corgis and basset hounds.
<img loading="lazy" decoding="async" class="alignleft size-full wp-image-4080" title="dachsund" src="https://blog-api.23andme.com/wp-content/uploads/2009/07/dachsund.jpg" alt="dachsund" width="221" height="315" srcset="https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2009/07/dachsund.jpg 300w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2009/07/dachsund-210x300.jpg 210w" sizes="auto, (max-width: 221px) 100vw, 221px" />
Ostrander&#8217;s group found that dogs having stubby little legs, technically termed chondrodysplasia, harbor an extra copy of a growth factor gene called FGF4.   But this is no ordinary gene duplication that happened as the result of a DNA replication error.
Instead, the researchers found that the extra copy of FGF4 is a retrogene, a piece of DNA copied from and then inserted back into the dog genome by a virus. Retrogenes are nothing new.   They&#8217;re known to be a major source of genetic change that takes place as different species split apart from each other.
But this new study is the first to show that a retrogene can cause long-lasting variation within a species. The various stumpy-legged dog breeds were developed in different places around the world, at different times and for various reasons.
So there&#8217;s no evidence that they share a recent common ancestor.   But the FGF4 retrogene appears to be identical in all of them, suggesting to the researchers that it arose only once, probably before early dogs split into modern breeds. These new findings don&#8217;t just represent an advance in the understanding of dog genetics, or even the fundamentals of DNA and evolution.   They also have implications for human health.   The type of growth disorder seen in the dogs with the retrogene is reminiscent of <a href="http://ghr.nlm.nih.gov/condition=hypochondroplasia" target="_blank" rel="noopener noreferrer">hypochondroplasia</a>, a type of dwarfism.   Scientists know that a mutation in one gene is responsible for most cases of this condition, but the cause of the rest remains a mystery.
According to Ostrander, her group&#8217;s results suggest that researchers interested in hypochondroplasia and other disorders of human growth and development should set their sights on FGF4. More Blog posts about dogs and genetics:
<ul>
<li><a href="https://blog.23andme.com/2008/11/07/gene-links-gout-in-humans-with-bladder-stones-in-dalmatian-dogs/" target="_blank" rel="noopener noreferrer">Gene Links Gout in Humans with Bladder Stones in Dalmatian Dogs</a></li>
<li><a href="https://blog.23andme.com/2008/08/07/learning-from-dog-eye-disorders/" target="_blank" rel="noopener noreferrer">Learning from Dog Eye Disorders</a></li>
</ul>
Picture Sources:
<ul>
<li><a href="https://en.wikipedia.org/wiki/File:MaddytheBHOUND.JPG" target="_blank" rel="noopener noreferrer">Basset hound</a></li>
<li><a href="https://en.wikipedia.org/wiki/File:Wire-haired_Dachshund_R_01.JPG" target="_blank" rel="noopener noreferrer">Dachshund</a></li>
</ul>

Single Gene Responsible For Stubby Legs In Dogs

Each year from September 15–October 15, National Hispanic Heritage Month celebrates the histories, cultures, and contributions of people from Spain, Latin America, and other Spanish-speaking communities. To mark the occasion, we’re highlighting a remarkable ancient DNA study from Las Gobas, a medieval site in northern Spain that sheds new light on life in early Iberia, which comprises present-day Spain and Portugal.



<h2 class="wp-block-heading" id="h-setting-the-scene-iberia-in-the-early-medieval-period">Setting the Scene: Iberia in the Early Medieval Period</h2>



From the 5th to 8th centuries CE, Iberia was ruled by the Visigoths, a Germanic people who established power after the fall of the Western Roman Empire. In 711 CE, their kingdom collapsed after the Umayyads—an Islamic dynasty with roots in Arabia and North Africa—invaded and established the Emirate (and later the Caliphate) of Córdoba. This new state controlled much of Iberia, along with the Balearic Islands and parts of North Africa.



In the mountainous north, however, many communities retained their independence and Christian traditions, even as the rest of the Iberian peninsula underwent profound cultural and political change.



<h2 class="wp-block-heading" id="h-life-at-las-gobas">Life at Las Gobas</h2>



Las Gobas, located in today’s province of Burgos in northern Spain, consists of 13 rock-cut caves and several freestanding structures. Beginning in the 7th century, it served as a mixed-use settlement with homes, a Christian church, and a cemetery. By the late 9th century, the residential area was abandoned, but the site continued to be used as a burial ground and place of worship until the 11th century.



<a href="https://pubmed.ncbi.nlm.nih.gov/39196943/" target="_blank" rel="noreferrer noopener">In 2024</a>, researchers analyzed DNA from 33 individuals buried at Las Gobas. They discovered that the community’s ancestry remained surprisingly stable over the centuries, with little evidence of genetic influence from the Islamic expansion that reshaped much of Iberia.



Why was Las Gobas different? Their DNA offered a clue. Many individuals carried stretches of identical DNA inherited from both parents—patterns that often occur in small, insular populations with limited outside contact. This genetic isolation likely helped shield the community from broader population shifts happening elsewhere.



The study also revealed striking details about life at Las Gobas:



<ul class="wp-block-list">
<li>Inbreeding: The DNA of several individuals showed evidence that their parents were close relatives; likely first cousins or closer.</li>



<li>Disease: DNA evidence showed infections from multiple pathogens, including what may be one of the earliest documented cases of smallpox in northern Iberia.</li>



<li>Violence: Skeletal remains showed signs of traumatic injuries, likely from swords—evidence of interpersonal conflict or warfare.</li>
</ul>



Taken together, the findings paint a vivid—and sometimes harsh—picture of life more than a thousand years ago in a small, tightly knit community in northern Spain.



<h2 class="wp-block-heading" id="h-learn-more">Learn more</h2>



Want to see if you share a genetic connection with these newly added individuals from Las Gobas—or hundreds of other historical people? The <a href="https://blog.23andme.com/articles/23andmes-historic-matches" target="_blank" rel="noreferrer noopener">Historical Matches</a>SM feature is available to <a href="https://www.23andme.com/membership/" target="_blank" rel="noreferrer noopener">23andMe+ Premium</a>™ members.

New Historical Matches Could Connect You to the Medieval Iberian Site of Las Gobas

<a href="https://blog.23andme.com/articles/ancestry-composition-version-7-is-here" target="_blank" rel="noreferrer noopener">This update</a> is currently available to all eligible customers on the latest, V5, genotyping chip.



23andMe’s flagship Ancestry Composition algorithm was last updated in 2022, when three new reference populations were added in China. Since then, the 23andMe Ancestry Team has focused on improving the specificity of reference populations and updating the methods underlying this state-of-the art algorithm. The result? More specificity and accuracy in the ancestry breakdowns we provide.&nbsp;



<figure class="wp-block-image size-large"><img loading="lazy" decoding="async" width="1024" height="508" src="http://35.88.189.111/wp-content/uploads/2025/09/Ac-omega-map-correc-1024x508.png" alt="" class="wp-image-34246" srcset="https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/09/Ac-omega-map-correc-1024x508.png 1024w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/09/Ac-omega-map-correc-300x149.png 300w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/09/Ac-omega-map-correc-768x381.png 768w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/09/Ac-omega-map-correc-880x437.png 880w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/09/Ac-omega-map-correc-1180x585.png 1180w" sizes="auto, (max-width: 1024px) 100vw, 1024px" /></figure>



The project, Version 7 of Ancestry Composition, is the most significant update to the feature ever.



<h2 class="wp-block-heading" id="h-improved-algorithm-expanded-populations-better-results">Improved algorithm, expanded populations, better results</h2>



Over the last few months, we’ve been hard at work finalizing the details on this major update to your favorite report: Ancestry Composition.&nbsp;



<figure class="wp-block-image size-large is-resized"><img loading="lazy" decoding="async" width="1024" height="499" src="http://35.88.189.111/wp-content/uploads/2025/09/image-3-1024x499.png" alt="" class="wp-image-34237" style="width:537px;height:auto" srcset="https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/09/image-3-1024x499.png 1024w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/09/image-3-300x146.png 300w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/09/image-3-768x374.png 768w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/09/image-3-880x429.png 880w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/09/image-3-1180x575.png 1180w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/09/image-3.png 1600w" sizes="auto, (max-width: 1024px) 100vw, 1024px" /></figure>



Here’s what we&#8217;ve been working on:



<ul class="wp-block-list">
<li>Better breakdowns in Europe and the Americas: Thanks mainly to consented 23andMe research participants we&#8217;ve been able to expand the number of unique populations in our reference datasets. Reference datasets are collections of DNA samples from people with deep roots in a specific part of the world. It&#8217;s what is needed to compare each piece of your DNA to in order to determine where in the world that DNA most likely came from. What this means is we’re launching with nearly four times the resolution in Europe and six new populations in the Americas. We also took the opportunity to refine reference datasets from around the world, making them more specific to each global population.</li>



<li>Enhanced Accuracy: The accuracy of these new ancestry results are greatly improved by using our <a href="https://www.cell.com/hgg-advances/fulltext/S2666-2477(25)00082-X" target="_blank" rel="noreferrer noopener">recently published</a>, state-of-the-art DNA phasing method. You could think of phasing as sorting which DNA you inherited from each parent. Reducing errors in phasing means a more accurate estimate of your ancestry percentages and better <a href="https://customercare.23andme.com/hc/en-us/articles/212860507-Chromosome-Painting-23andMe-Ancestry-Results" target="_blank" rel="noreferrer noopener">DNA Painting</a>.&nbsp;</li>



<li>Elimination of Broadly and Unassigned DNA: We are updating our algorithm to report the most likely assignment for a given stretch of DNA rather than at a fixed confidence threshold. This will have the benefit of eliminating &#8220;Broadly&#8221; and &#8220;Unassigned&#8221; categories in the default results view. You will still be able to view your results at different confidence thresholds in the Version History section.</li>



<li>Better Error Detection: We&#8217;ve upgraded our smoother to better filter out erroneous trace ancestries between two larger blocks of ancestry. See our <a href="https://www.23andme.com/ancestry-composition-guide/" target="_blank" rel="noreferrer noopener">Ancestry Composition Guide</a> for more information about the current smoother.</li>



<li>Version History: Compare your new results to your old ones in a new &#8220;Version History&#8221; section. <a href="https://www.23andme.com/membership/" target="_blank" rel="noreferrer noopener">23andMe+ Premium</a>™ members will also be able to access previous versions at different confidence settings.</li>
</ul>



<h2 class="wp-block-heading" id="h-what-are-the-new-reference-populations-nbsp">What are the new reference populations?&nbsp;</h2>



<ul class="wp-block-list">
<li>33 new ancestry populations in Europe are coming: Albanian &amp; Macedonian; Andalusian, Asturian &amp; Castilian; Aragonese &amp; Catalan; Austrian &amp; Southern German; Basque; Belarusian, Polish &amp; Ukrainian; Belgian, Rhinelander &amp; Southern Dutch; Bosnian, Croatian, Montenegrin &amp; Serbian; Bulgarian, Moldovan &amp; Romanian; Canary Islander; Czech, Hungarian, Slovak &amp; Southern Polish; Danish; Dutch &amp; Northern German; English; Estonian; Finnish; French; Greek; Icelandic; Irish; Kosovar &amp; Northern Albanian; Latvian; Lithuanian; Maltese; Northern Italian; Norwegian; Portuguese &amp; Galician; Russian; Sardinian; Scottish; Slovenian; Southern Italian; Swedish; Swiss, Southwestern German &amp; Western Austrian; Welsh</li>
</ul>



<figure class="wp-block-image size-large is-resized"><img loading="lazy" decoding="async" width="1024" height="840" src="http://35.88.189.111/wp-content/uploads/2025/09/europe_map-1024x840.png" alt="" class="wp-image-34262" style="width:523px;height:auto" srcset="https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/09/europe_map-1024x840.png 1024w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/09/europe_map-300x246.png 300w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/09/europe_map-768x630.png 768w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/09/europe_map-880x722.png 880w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/09/europe_map.png 1101w" sizes="auto, (max-width: 1024px) 100vw, 1024px" /></figure>



<ul class="wp-block-list">
<li>Indigenous American will be broken into 6 new ancestry populations: Arctic North American, Central Andean &amp; Amazonian, North American, Northern Andean, Southern Mesoamerican, and Western North American</li>
</ul>



<figure class="wp-block-image size-full"><img loading="lazy" decoding="async" width="562" height="393" src="http://35.88.189.111/wp-content/uploads/2025/09/image-2.png" alt="" class="wp-image-34236" srcset="https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/09/image-2.png 562w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2025/09/image-2-300x210.png 300w" sizes="auto, (max-width: 562px) 100vw, 562px" /></figure>



<h2 class="wp-block-heading" id="h-your-dna-story-now-clearer-across-time-place-and-family">Your DNA story, now clearer across time, place, and family</h2>



These updates, drawn from sharper science and richer data, power everything you use to explore your ancestry, including Ancestry Timeline, Parental Inheritance, DNA Painting, and more. This builds on the world’s most comprehensive ancestry breakdown on the market with over 4,000 regions, helping you experience the life-changing power of DNA by tracing where your ancestors lived and what they passed on to you.



Ancestry Composition, Version 7. More precision. More connection. More you.



This is a massive project for us and a chance to get back to our roots by digging deeper into yours. We’re thrilled you’re as excited as we are.



The 23andMe Ancestry Team

A Major Update to Ancestry Composition

A massive new study, the largest genome-wide association study ever done, has found nearly all the common genetic variants that explain the heritability of height among people of European ancestry, and in the process may have set the framework for future genetic research into other traits and diseases.<img loading="lazy" decoding="async" src="https://blog-api.23andme.com/wp-content/uploads/2008/04/tallshadow-225x300.jpg" alt="" width="225" height="300" class="alignright size-medium wp-image-180" srcset="https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2008/04/tallshadow-225x300.jpg 225w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2008/04/tallshadow.jpg 300w" sizes="auto, (max-width: 225px) 100vw, 225px" />
Using data from about 5.4 million individuals, almost half of whom were 23andMe customers who consented to participate in research, the study identified 12,111 variants or single nucleotide polymorphisms (SNPs) that help explain differences in height.
“We feel that this is really a milestone,” said&nbsp;<a href="https://www.broadinstitute.org/node/7053">Joel Hirschhorn</a>, senior author on the study, an institute member at the Broad, and also a professor of genetics and Concordia Professor of Pediatrics at Boston Children’s Hospital and Harvard Medical School. “We’d been studying height for a while but had only identified a small fraction of common variant heritability. We’re now basically done mapping this heritability to specific genomic regions, and that highlights what increasing sample size can tell us about traits controlled by multiple genes.”
<h6>GIANT</h6>
Published in the journal <a href="https://www.nature.com/articles/s41586-022-05275-y">Nature</a>, the study, led by researchers at the <a href="https://www.broadinstitute.org/news/largest-genome-wide-association-study-ever-uncovers-nearly-all-genetic-variants-linked-height">Broad Institute</a> and the international <a href="https://portals.broadinstitute.org/collaboration/giant/index.php/GIANT_consortium">Genetic Investigation of ANthropometric Traits (GIANT) Consortium</a>, is the culmination of a multi-year effort to foster collaboration between academic, non-profit, government, and commercial partners. In their effort, the researchers collected, merged, and analyzed numerous independently generated genome-wide association studies into a single data set. In all, there are more than 200 different datasets incorporated into this study, which included contributions from hundreds of scientists from around the world.
<h6>The Power of Scale</h6>
What they found is important not just because of what it says about height, syndromes, and abnormalities affecting stature, but what it says about the potential of using very, very large amounts of data to generate insights into the genetics of different traits and conditions. Because height is so heritable, and because it is easy to measure someone’s height, it offers a very straightforward way to conduct a genetic study into a trait.
&#8220;This study highlights the ability of large-scale genetic studies to reveal the underlying biology of human phenotypes,” said Adam Auton, 23andMe’s Vice President of Human Genetics. 23andMe was one of a long list of institutions and organizations involved in the study.
“With this 5.4 million person study, we&#8217;re now at the stage where we&#8217;re starting to saturate our genetic understanding of height,” Auton said. “However, for other phenotypes — particularly human diseases — we&#8217;re a long way from saturation, and there is a lot we don&#8217;t yet understand.&#8221;
<h6>Heritability of Height</h6>
Heritability is the measure of how much our DNA explains the differences in specific traits or conditions. A SNP is a one-letter variation in the genetic code at a single point along the genome. These common variants are associated with differences in everything from traits like the color of our eyes or our height, or our risk for certain diseases.
Along with genetics, one’s environment — diet, for instance — also plays a role in these different traits and conditions. In the case of height, genetics has an outsized role in explaining about 80 percent of the variation. Because researchers included more than twice the number of individuals in this study from the next largest height study, they were able to discern almost all the heritability for height. So, size matters in genetic studies.
Previous height studies were large but just not large enough. According to the authors, this study was big enough to discern almost all of the heritability for height. In finding most of the variants that explain the heritability for height, the authors estimate that they’ve now identified variants that account for 40 percent of all variation in height in people with European ancestry. But they’ve identified only around 10–20 percent of the variation in people of other ancestries.
<h6>Diversity Matters</h6>
Also significant is that the study found that the genetic variants associated with height clustered within or near genes or gene regions associated with growth and development. That makes sense, but scientists were not so sure that is what they’d find. Many scientists thought that perhaps the variants they’ve identified could be found randomly sprinkled throughout the genome. But seeing that there is clustering will allow researchers to focus more on the clues around the biology and processes involved in individual traits like height.
In addition, the study illustrates something we already know about genetic research: diversity matters.&nbsp;
Although there were large numbers of individuals – more than a million – with African, Asian, and Latino ancestry included in this study, the vast majority of the data came from people of European ancestry. Some of the variants associated with height were associated with individuals of all different ancestries, but the findings were most applicable to those of European ancestry.&nbsp;
The researchers concluded that their study would benefit from data from a more diverse pool of individuals, especially those of African ancestry since people of African ancestry have the most genetic diversity of all populations. Not only would it improve the predictive power of the models developed to predict height for non-Europeans,&nbsp; it would also help in identifying causal genes and rare variants involved in height.
Read the full paper <a href="https://www.nature.com/articles/s41586-022-05275-y">here</a>.
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Giant Study Offers Insights into the Genetics of Height

If you think that opposites attract, you are likely mistaken, or at least that&#8217;s what the science says. Over a hundred years ago, researchers first discovered that couples are actually more alike than <img loading="lazy" decoding="async" class="alignright size-medium wp-image-17437" src="https://blog-api.23andme.com/wp-content/uploads/2013/02/AfricanAmericanCoupleHeart-200x300.jpg" alt="AfricanAmericanCoupleHeart" width="200" height="300" srcset="https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2013/02/AfricanAmericanCoupleHeart-200x300.jpg 200w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2013/02/AfricanAmericanCoupleHeart.jpg 283w" sizes="auto, (max-width: 200px) 100vw, 200px" />they are different.


One of the first things researchers noted was that tall people tend to partner with other tall people. Since then, studies of this phenomena – called &#8220;assortative mating&#8221; – have found strong correlations among couples for almost all traits, including behavior, personality, and disease risk.


There are  a lot of reasons for this. Love is complicated, and figuring out precisely why couples get together is tricky.
But a new study the journal <a href="https://www.nature.com/articles/s41562-016-0016">Nature Human Behavior</a> has identified genetic evidence for assortative mating, reporting that, at least for one trait, height, there is a strong correlation between the genetic variants that influence height in one partner and the actual height of the other.
In this  study, researchers from the University of Queensland in Brisbane, Australia, the University of North Carolina, 23andMe and dozens of other institutions, were able to look specifically at genetic factors by using a new design and analytical approach that allowed for them to carefully control for non-genetic influences. 
Isolating all the different cultural and social influences involved in why people partner up, isn&#8217;t easy, however. We may be attracted to our partners for any number of reasons. For instance, partners might have similar BMIs because people are attracted to individuals with a BMI that resembles their own. Or, they might choose a partner who is culturally similar. Alternatively, their BMIs might converge over time due to shared environment.


To isolate some of those kinds of influences the researchers in this study used data from more than 24,000 couples, including 11,908 from 23andMe, and compared an individual’s genetically-predicted height and BMI to those of their partner. Because genetics are determined at birth, these shouldn’t be correlated if partners become more similar only after meeting each other.
The researchers also controlled for population, to remove the effects of shared cultural background.
They found a strong correlation between people’s genetic predisposition for height and the actual height of their partner. The findings showed that similarity in couples’ heights can be largely explained by people selecting mates who are like them. Tall people, it seems, are attracted to other tall people.
But the findings were not as strong for BMI, where there was a weaker correlation between people’s genetic contributions to BMI and the actual BMI of their partners.
One possible implication of this is that “mate choice” may, in turn, affect the genetic architecture of traits in humans as well. Assortative mating may increase the odds of parents passing on a trait, like height, to their children.


“These results have implications for the interpretation of resemblance between relatives and for estimates of genetic parameters in populations,” the researchers said.
You can find the paper in the journal <a href="https://www.nature.com/articles/s41562-016-0016">Nature</a>.

Genetic evidence of assortative mating in humans

By Alison Chubb
We&#8217;ve all known teenagers who grow several inches in a year, and then start bumping into people and furniture as they figure out what to do with their big feet and long arms.
The growth spurt that happens during adolescence can account for up to 20 percent of one&#8217;s final height, <img loading="lazy" decoding="async" class="size-full wp-image-19114 alignright" src="https://blog-api.23andme.com/wp-content/uploads/2013/08/KidsHeight.jpg" alt="KidsHeight" width="316" height="380" srcset="https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2013/08/KidsHeight.jpg 316w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2013/08/KidsHeight-249x300.jpg 249w" sizes="auto, (max-width: 316px) 100vw, 316px" />and we know that <a href="https://www.ncbi.nlm.nih.gov/pubmed/18203123">genetics</a> is largely responsible for why kids grow less or more, during that time. But until now, we didn&#8217;t know much about the genetic variants involved in this sometimes awkward phase of childhood growth.
<h6>Growth Data</h6>
Recently, <a href="https://www.ncbi.nlm.nih.gov/pubmed/23449627">researchers</a> from the Early Growth Genetics Consortium analyzed growth data from over 10,000 people of European descent looking for genes relevant to childhood growth rates. They found genetic variants linked to height and growth during adolescence and published their results in the journal Human Molecular Genetics.
The single-nucleotide polymorphism (SNP) was associated with late adolescent growth. People with the C version of this SNP tended to grow slightly more between the ages of 14 and 18 compared to people without the C version. This SNP is located near LIN28B, a gene linked to <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2869010/">height in adulthood</a> and <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3140055/">age at menarche</a> (first period).
<h6>Puberty</h6>
Another SNP was associated with overall adolescent growth. People with the A version of this SNP tended to grow slightly more between the ages of eight and 18, while those with the G version tended to grow slightly less.
The researchers also discovered that women with the G version of experienced their <a href="https://www.23andme.com/health/menarche/">first period</a> at a slightly earlier age, on average. This marker is located near ADCY3 and POMC, two genes implicated in <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3370100/">childhood</a> and <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3014648/">adult obesity</a>. ADCY3 is an enzyme important for communication between cells throughout the body, and POMC is expressed in the pituitary gland that releases several hormones important for growth.
We know from epidemiological studies that <a href="http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0008450">obesity during childhood </a>is linked to earlier puberty, and that earlier puberty raises the risk for obesity and possibly other health conditions in adults.
This new study is interesting because it shows that some of the genetic factors underlying obesity and growth patterns in childhood may overlap, and that they may also influence risk for other diseases in adults, but much more research is needed to unravel these complicated genetic connections.

The Genetics of Adolescent Growth Spurts

<img loading="lazy" decoding="async" class="alignnone size-medium wp-image-11941" src="https://blog-api.23andme.com/wp-content/uploads/2012/03/Sport-Fan-300x199.jpg" alt="" width="300" height="199" srcset="https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2012/03/Sport-Fan-300x199.jpg 300w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2012/03/Sport-Fan.jpg 425w" sizes="auto, (max-width: 300px) 100vw, 300px" />
It’s that time of year again. That’s right&#8230; it’s <a href="https://en.wikipedia.org/wiki/NCAA_Men%27s_Division_I_Basketball_Championship" target="_blank" rel="noopener noreferrer">March Madness</a> and time to follow your favorite U.S. college basketball teams during playoffs. Some of you may be baffled by how much mental energy, time, and money Americans invest in sporting events, but those who participate will expound on the excitement of watching spectacular athletes and the thrill of competition, or simply the fun of betting on the outcome.
Investigating the different angles of March Madness turns out to be pretty interesting from a genetic perspective. First there is the genetics underlying athleticism, a trait that combines physical attributes like strength, coordination and stamina along with psychological behaviors – the ability to focus, to persevere and to compete. Then there is the genetics of the “spectator” who nearly becomes obsessed with basketball in these last two weeks of March. 
 
Genetic factors for the basketball player 
Being tall and getting across the court quickly might make you a better basketball player. Although height clearly has many contributing environmental factors, it also has a <a href="https://www.23andme.com/health/Height/" target="_blank" rel="noopener noreferrer">strong genetic component</a> and researchers have found several inherited factors that contribute to height in people of European descent. For instance, those with at least one T at rs6060371 and one C at rs1042725 tended to be slightly taller on average.
As for dashing across the court, <a href="https://www.23andme.com/health/Muscle-Performance/" target="_blank" rel="noopener noreferrer">research suggests</a> that a SNP in the ACTN3 gene known as “R577X” (rs1815739) is linked to “fast-twitch” muscle fiber function. <a href="http://www.23andme.com/topics/wellness/muscle-composition/">Fast-twitch muscle fibers</a> are important for power events like sprinting and the C version of this SNP is carried by many world-class sprinters and some endurance athletes.
Although it’s likely that there are additional genetic and environmental factors that influence whether you’ll become a basketball star, these are a few that might help you make that basket.
Genetic factors for the spectator 
Unfortunately much less is known about why some people love watching basketball (or sports in general) and to our knowledge, scientists haven’t yet correlated genetic factors with this interesting behavior! It’s possible, however, that sex and environment are involved. One <a href="http://www.questia.com/googleScholar.qst?docId=5002364547" target="_blank" rel="noopener noreferrer">study</a> showed that women are just as likely as men to report being sport fans, but men overall participate in more fan behavior. Women also seem to watch sports more if they do so with family and friends, though men follow sports because they themselves play and they enjoy the trivia aspect of following sports.
So whether you are an aspiring basketball player, a passionate spectator, or simply enjoy watching curiously from afar, it’s clear that the genetics underlying March Madness is very complex. Perhaps with time researchers will sort out the role of genetics in these two very interesting arenas of athleticism and fan behavior.

Did You Know? Genetics Might Influence “March Madness”

<img loading="lazy" decoding="async" class="alignnone size-medium wp-image-9867" src="https://blog-api.23andme.com/wp-content/uploads/2011/09/babyteethiSTock1-300x199.jpg" alt="" width="300" height="199" srcset="https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2011/09/babyteethiSTock1-300x199.jpg 300w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2011/09/babyteethiSTock1.jpg 425w" sizes="auto, (max-width: 300px) 100vw, 300px" />
By Bethann Hromatka, Ph.D.
Anyone who’s ever spent time around babies knows that teething can be disruptive and often painful. In that sense, the somewhat violent term “tooth eruption”–referring to the process of teeth breaking through the gums–seems rather appropriate.
Most people experience this phenomenon twice, first when baby teeth come in and again between six and 13 years of age when permanent teeth appear. Some people also have wisdom teeth, which are molars that develop in young adults.
While tooth development can be influenced by environmental factors, genetics also plays a role in both the timing of tooth emergence as well as the number of teeth a person ends up with. Subtle differences in tooth development are very common–for instance roughly 10% of the population is missing some teeth.
A genome-wide association study (GWAS) published in PLoS Genetics this month by <a href="http://www.plosgenetics.org/article/info%3Adoi%2F10.1371%2Fjournal.pgen.1002275" target="_blank" rel="noopener">researchers in Denmark</a> has now identified genetic factors associated with the emergence of permanent teeth. They analyzed DNA from nearly 9,000 individuals in Denmark and the United States, and found four SNPs that influenced the timing and number of visible teeth at various ages.
For at least three of these SNPs found in this study, the version associated with fewer teeth is relatively common in the population. And although the individual effects of the variants are small – correlated with about half to one tooth fewer, on average – they did seem to add up. In this study, someone with two copies of the “delayed tooth eruption” version at all four SNPs had about six fewer teeth (16 teeth) at 10-12 years of age compared to someone with no copies of the delayed versions (22 teeth).
Interestingly, a <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1000856" target="_blank" rel="noopener">study published a few years ago</a> showed that two of these SNPs might also play a role in the <a href="https://blog.23andme.com/2010/03/04/snpwatch-researchers-identify-variations-associated-with-when-junior-gets-his-first-chompers/" target="_blank" rel="noopener">eruption of baby teeth</a>.<a href="../2010/03/04/snpwatch-researchers-identify-variations-associated-with-when-junior-gets-his-first-chompers/"> 
</a>
Some genetic factors contribute to multiple growth-related traits, so the authors tested if the tooth development SNPs were also linked to traits such as age at menarche (first period in young women) and adult height. In general, the genetic factors underlying these traits did not overlap. There was, however, weak evidence suggesting that several of the SNPs associated with permanent tooth development also influence adult height and breast cancer. More research is needed to determine the exact biological mechanisms linking these different traits.
This study represents the first GWAS to look for genetic factors involved in permanent tooth eruption. Studies like this one are interesting because they reveal that there is clearly natural variation across the population–some individuals have more teeth while others have less. These findings also highlight the complex interplay between genetic factors involved in human growth and development.

Factors Influencing Permanent Tooth Development

<img loading="lazy" decoding="async" class="alignright size-full wp-image-2154" title="tallshort" src="https://blog-api.23andme.com/wp-content/uploads/2008/12/tallshort.jpg" alt="" width="400" height="300" srcset="https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2008/12/tallshort.jpg 400w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2008/12/tallshort-300x225.jpg 300w" sizes="auto, (max-width: 400px) 100vw, 400px" />
The genetics of height is incredibly complex. Though height is strongly determined by genetics, no single gene appears to have much influence over how tall a person will be. Instead, there appear to be dozens of genetic variants involved, none of which account for more than a few millimeters&#8217; height difference.
It will be no small feat for geneticists to identify all of the genetic contributors to height and out how they work together. But by analyzing growth data for a group of 3,538 people who were born in northern Finland in 1966, an international group of researchers has taken a step in that direction by figuring out when a few height-related genes exert their effects. They describe their research in the March issue of <a href="http://www.plosgenetics.org/article/info%3Adoi%2F10.1371%2Fjournal.pgen.1000409" target="_blank" rel="noopener">PLoS Genetics</a>.

Humans tend to do most of their growing in two spurts, once during infancy and then again around the onset of puberty. Growth during infancy tends to be associated with how much nutrition a child absorbs, whereas the second growth spurt is governed more by hormonal signals. So it would not be surprising to find that different sets of genes are associated with growth during the two periods.
The researchers tested that theory by selecting 48 SNPs that have been associated with adult height in previous studies. Then they looked at growth data for each subject from birth to age 20 to determine whether any of those SNPs was associated with growth during infancy, around puberty or both.
Five SNPs were significantly associated with growth during infancy, and seven with the puberty-associated growth spurt. Only one was associated with growth during both periods.
The researchers were especially interested in two SNPs. One was in the gene SOCS2, which influences growth hormone signaling, and was associated with growth during puberty. The other was in the gene HHIP, which is involved in embryogenesis and development, and was associated with growth during infancy.
(23andMe customers can check their genotype for both of these SNPs using the Genome Browser. Each T version of the SOCS2 SNP was associated with faster growth during infancy, and 4.7 mm of adult height. Each A version of the HHIP SNP was associated with faster growth around the time of puberty, but was not significantly related to adult height.)
This research illustrates the value of collecting data over time in genetic association studies. Knowing not just whether, but when, a particular genetic variation exerts its effects can provide vital clues to how it works.

New Study Shows When Some Height-Associated Genes Influence Growth

<img loading="lazy" decoding="async" class="alignright size-full wp-image-2154" title="tallshort" src="https://blog-api.23andme.com/wp-content/uploads/2008/12/tallshort.jpg" alt="" width="400" height="300" srcset="https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2008/12/tallshort.jpg 400w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2008/12/tallshort-300x225.jpg 300w" sizes="auto, (max-width: 400px) 100vw, 400px" />
A new genome-wide association study has yielded two more genes associated with height. But just like the amount of height difference the new genes explain, their discovery amounts to no more than an inch of progress in understanding the genetics of the trait.
Height is one of the most genetically complex traits scientists face. There are probably hundreds of different genes that influence stature, with each one accounting for only a tiny fraction of the difference in height from one person to the next. And though genes are by far the most important determinant of height, all other things being equal, all other things are by no means equal. Differences in childhood nutrition, prenatal care and infection history can cause even identical twins can to reach very different heights (more on that <a href="http://www.sciam.com/article.cfm?id=how-much-of-human-height" target="_blank" rel="noopener">here</a>).

Discerning the effect of a single genetic variation in such a noisy environment requires multiple studies involving large numbers of subjects. The latest study, published online last week by Human Molecular Genetics, looked at 379,319 SNPs in 1,000 people of European descent.
The study found statistically significant associations with height for 134 SNPs. The researchers focused on about two dozen that clustered around two genes that had not previously been associated with height, SBF2 and FLNB.
FLNB is plausible as a height-associated gene, because it is involved in skeletal development. Though SBF2 is not as clearly related to height, mutations in the gene are known to cause <a href="http://www.ninds.nih.gov/disorders/charcot_marie_tooth/detail_charcot_marie_tooth.htm" target="_blank" rel="noopener">Charcot-Marie-Tooth disease</a>, which causes muscle weakness and skeletal deformities in the limbs.
The effect of SBF2 was surprisingly large – subjects with the TT genotype at one SNP in the gene, rs1867138, were about an inch taller on average than those with the CC genotype. Though the effect of FLNB was less impressive, the study found that each G at the the SNP rs9834312 in that gene slightly increased a subject&#8217;s height.
23andMe customers can check their genotypes at two equivalent SNPs using the <a href="https://www.23andme.com/you/explorer/" target="_self" rel="noopener">Browse Raw Data</a> feature. Having a G at rs1867137 is the same as having a T at rs1867138. So the GG genotype at rs1867137 is worth about an inch compared to AA. In FLNB, rs939882 is equivalent to rs9834312. In both cases, having a G is correlated with slightly greater height.
When the researchers attempted to replicate their findings in Chinese subjects, they found that both genes were associated with height in that population as well – but not all of it. The SNP in FLNB was associated with height among 619 northern Chinese subjects, while the SNP in SBF2 was associated with height only in a sample of 2,953 southern Chinese.
But when the researchers tried to replicate previously discovered height associations using their data, their results were mixed. Out of 58 they looked for, only 13 showed up. That doesn&#8217;t necessarily mean the 45 associations that could not be replicated are invalid; but it does illustrate how difficult it will be to work out the genetic basis of height.

Two More Genes Associated with Height

<div style="width: 160px" class="wp-caption alignright"><img loading="lazy" decoding="async" class="right" src="https://blog-api.23andme.com/wp-content/uploads/2008/04/tallshadow2.jpg" alt="tallshadow2.jpg" width="150" height="200" />Photo by Dave2003/istockphoto</div>
Three articles published online this week in the journal <a href="https://www.nature.com/ng/index.html" target="_blank" rel="noopener noreferrer">Nature Genetics</a> report a bumper crop of SNPs associated with human height.
Unlike other physical characteristics such as obesity that are caused by a mix of genetic and environmental factors, 90% of normal variation in human height is due to DNA alone. But unraveling the details of the genetics has been difficult.
Last year, two large studies (<a href="https://www.ncbi.nlm.nih.gov/pubmed/17767157?ordinalpos=1&#038;itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum" target="_blank" rel="noopener noreferrer">here</a> and <a href="https://www.ncbi.nlm.nih.gov/pubmed/18193045?ordinalpos=2&#038;itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum" target="_blank" rel="noopener noreferrer">here</a>) looked for SNPs associated with height. Only two convincing candidates were found. Both of them accounted for only about a half-centimeter difference in height.
<h6>New Studies</h6>
The three new studies (<a href="https://dx.doi.org/10.1038/ng.121" target="_blank" rel="noopener noreferrer">here</a>, <a href="https://dx.doi.org/10.1038/ng.125" target="_blank" rel="noopener noreferrer">here</a>, and <a href="https://dx.doi.org/10.1038/ng.122" target="_blank" rel="noopener noreferrer">here</a>) were able to find more SNPs associated with height. The studies were successful by using extremely large sample sizes. Two of the studies had more than 30,000 participants and the third study looked at more than 15,000 people. Large sample sizes increase the chance that SNPs with small effects will be found.
Like the previously found height SNPs, the new SNPs each individually account for only a fraction of a centimeter in height difference.
The authors of all three papers note that statistical analyses of their data indicate that many more small effect SNPs are waiting to be found. Even bigger sample sizes may be necessary to detect these SNPs.
Many of the SNPs associated with height are in genes with well-documented functions in processes such as cell division, cell-to-cell signaling, and gene regulation.
<h6>New Associations</h6>
Other SNPs, however, are in genes about which little is known.
“There may be more than a hundred genes which affect our height,&#8221; said Mike Weedon, lead author of one of the papers. &#8220;Many of which will work in surprising or unpredicted ways.”
“The challenge now for us is to understand how they influence growth in the body. This could open up new avenues for treating a range of diseases,” said Weedon.
Want to know how you stack up?
23andMe users can see their data for 46 distinct height-related SNPs in the Genome Explorer (now called Browse Raw Data) (in some cases we substitute a SNP from the three new studies with an equivalent one that is included on our chip).
We’ve used the data in each paper to calculate the approximate effect in centimeters for each SNP. The effect shown is the increase in height (in cm) that each copy of the &#8220;tall&#8221; version of the SNP would give a person compared to someone who had two &#8220;short&#8221; versions. At this point, these findings apply only to people of European ancestry.
<img decoding="async" class="left" src="https://blog-api.23andme.com/wp-content/uploads/2008/04/picture-5.png" alt="picture-5.png" />
 
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