Editor&#8217;s note: This post has been slightly edited since being posted in 2013.
By David Tran
Look at your hands. Is your ring finger longer than your index finger, or vice versa?
The length of a person’s index finger relative to his or her ring finger may tell us something about that individual&#8217;s exposure to <a href="http://www.psychologytoday.com/articles/200612/the-sex-hormone-secrets">sex hormones</a> when he or she was still in the womb. But genetics also plays a big role here and recent studies are shedding light on the interplay between all these factors.
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<img loading="lazy" decoding="async" class="aligncenter size-medium wp-image-18878" src="https://blog-api.23andme.com/wp-content/uploads/2013/08/digit-ratio-histogram-flat11-300x270.jpg" alt="digit ratio histogram flat(1)" width="300" height="270" srcset="https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2013/08/digit-ratio-histogram-flat11-300x270.jpg 300w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2013/08/digit-ratio-histogram-flat11-768x692.jpg 768w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2013/08/digit-ratio-histogram-flat11-880x793.jpg 880w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2013/08/digit-ratio-histogram-flat11.jpg 900w" sizes="auto, (max-width: 300px) 100vw, 300px" />
This graph shows the estimated distribution of people with different index to ring finger length ratios (X-axis). There&#8217;s a small but consistent pattern where women tend to have larger ratios. 

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While this may seem trivial, understanding how genetics and environmental factors influence finger length may give us insight into important biological functions.
<h2>Finger Length</h2>
It may help us understand not just bone development but also other seemingly unrelated traits and conditions. Recent studies show that people with autism tend to have a smaller index-to-ring finger ratio. In contrast, other studies have suggested associations between finger length ratio and prostate cancer, obesity, ADHD, and sexual orientation.
These findings are still preliminary; however, more research is needed.
Finger lengths have fascinated scientists for a long time.
<h2>Sex Differences</h2>
As early as 1875, researchers knew there was a difference between the sexes. For many women, the index finger is nearly the same length as the ring finger, while in men, the ring finger tends to be longer than the index finger.
On average, a woman&#8217;s index finger is about <a href="https://www.ncbi.nlm.nih.gov/pubmed/?term=20303062">97-98 percent</a> the length of her ring finger, while a man&#8217;s index finger is about <a href="https://www.ncbi.nlm.nih.gov/pubmed/?term=20303062">96-97 percent</a>. A ratio of 100 percent means your index finger is the same length as your ring finger.
<h2>Ratios</h2>
One thing to be aware of is that ratios can vary significantly between the left and right hands, so researchers often take the average of both hands.
These are not ironclad rules, so if your index to ring finger length ratio seems different from the average, don&#8217;t worry. Many people have a larger or smaller ratio. (See the accompanying graph for an estimation of the distribution of people with different finger ratios.)
You can see a lot of overlap between the sexes and changes in the ratios. Ratios change from person to person and may also be influenced by <a href="https://www.ncbi.nlm.nih.gov/pubmed/18433004">ancestry</a>.
<h2>The Genetics of Finger Length</h2>
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<img loading="lazy" decoding="async" class="aligncenter size-medium wp-image-18880" src="https://blog-api.23andme.com/wp-content/uploads/2013/08/finger-photo-191x300.jpg" alt="finger photo" width="191" height="300" srcset="https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2013/08/finger-photo-191x300.jpg 191w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2013/08/finger-photo-653x1024.jpg 653w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2013/08/finger-photo-561x880.jpg 561w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2013/08/finger-photo-752x1180.jpg 752w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2013/08/finger-photo.jpg 765w" sizes="auto, (max-width: 191px) 100vw, 191px" />
Two volunteers from 23andMe allowed us to measure their fingers and you can see in the picture that the man has a 95% ratio while the woman has a 98% ratio. 

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In 2013, a team led by John Mollon at Cambridge University in England <a href="https://www.ncbi.nlm.nih.gov/pubmed/?term=23263445">reported</a> that the single nucleotide polymorphism (SNP) was associated with a finger length ratio in people of European ancestry.
One genotype was associated with a 0.8 percent increase in finger length ratio. Another was associated with a 0.8 percent decrease in finger length ratio. The SNP lies near the SMOC1 gene, which is known to regulate bone growth and has been hypothesized to control finger length growth. Independent studies have suggested that the activity of the SMOC1 gene is controlled by <a href="https://www.ncbi.nlm.nih.gov/pubmed/?term=18794802">testosterone</a> and <a href="https://www.ncbi.nlm.nih.gov/pubmed/?term=17032503">estrogen</a> levels.
<h2>More Findings</h2>
In 2010, a <a href="https://www.ncbi.nlm.nih.gov/pubmed/?term=20303062">study</a> found that another SNP is associated with a 0.6 percent increase in finger length ratio. This SNP lies near the LIN28B gene, which is important for the development of the embryo and a key player in stem cell development. However, how sex hormones affect LIN28B is less clear.
Many researchers are interested in finger-length ratios because they may shed light on exposure to sex hormones in the womb. Some studies suggest that exposure to more estrogen than testosterone is linked to larger finger-length ratios, while more testosterone has the opposite effect, leading to smaller finger-length ratios.
<h2>Learn More</h2>
Find out if your <a href="https://www.23andme.com/test-info/genetic-health/">genetics</a> might Increase your risk for any health conditions with 23andMe.

A Tale of Two Fingers

Researchers at the University of Cambridge have found that it isn’t just your environment and experiences that influence your empathy for others, your genes also play a small but important role and this connection also sheds new light on the biology of autism.
“This is an important step towards understanding the small but important role that genetics plays in empathy,” said <a href="http://www.neuroscience.cam.ac.uk/directory/profile.php?vw260">Varun Warrier</a>, a Ph.D. student at the University Cambridge who led the study.
<div id="attachment_25991" style="width: 210px" class="wp-caption alignright"><img loading="lazy" decoding="async" aria-describedby="caption-attachment-25991" src="https://blog-api.23andme.com/wp-content/uploads/2018/01/sm_vw260_phpHPqcmu.jpg" alt="" class="wp-image-25991 size-full" width="200" height="257" />Varun Warrier</div>
Warrier said that while the genetic influences are important they still only play a small role in empathy. Other, non genetic factors, like upbringing, environment and other non-biological factors explain 90 percent of the individual differences in empathy between people, he said.
The study, published in the journal <a href="https://www.nature.com/articles/s41398-017-0082-6">Translational Psychiatry,</a> also confirms previous research that shows that women on average are more empathetic than men. However, this difference is not due to our DNA, which in turn implies that the sex difference in empathy is the result of other non-genetic biological factors such as prenatal hormonal influences, or non-biological factors, such as socialisation, both of which also differ between the sexes.
Finally, the new study found genetic variants associated with lower empathy are also associated with higher risk for autism. In fact the paper is part of a series of papers looking at the genetics of autism by this same group of researchers at Cambridge.
For this study — led by Warrier and Professor <a href="http://www.neuroscience.cam.ac.uk/directory/profile.php?sb205">Simon Baron-Cohen</a>, the director of the <a href="https://www.autismresearchcentre.com/">Autism Research Centre</a> at Cambridge, and with contributions from researchers at 23andMe, the University Paris Diderot, and Institut Pasteur — scientists used data from more than 46,000 23andMe customers who consented to participate in research and completed the online survey that measures their Empathy Quotient, or EQ. It was scientists at Cambridge who first developed the tool to measure empathy 15 years ago.
“This new study demonstrates a role for genes in empathy, but we are have not yet identified the specific genes that are involved in empathy,” said Professor Thomas Bourgeron of the University of Paris. “Our next step is to gather larger samples to replicate these findings and to pinpoint the precise genes associated with individual differences in empathy.”
<div id="attachment_25992" style="width: 210px" class="wp-caption alignright"><img loading="lazy" decoding="async" aria-describedby="caption-attachment-25992" src="https://blog-api.23andme.com/wp-content/uploads/2018/01/sm_sb205_phpdnwk32.jpg" alt="" class="wp-image-25992 size-full" width="200" height="271" />Simon Baron-Cohen, PhD</div>
23andMe is uniquely equipped for a study like this, said David Hinds, Ph.D., the company’s principal scientist and a statistical geneticist who worked on this study.
“We’re encouraged by these findings, which are the latest in <a href="https://blog.23andme.com/23andme-research/the-genetics-of-empathy/">a series of studies</a> we’ve collaborated on with researchers at Cambridge,” Hinds said. “Together they are are helping to reveal new insights into the genetics that influences autism.”
Empathy has two parts: “cognitive empathy,” the ability to recognize another person’s thoughts and feelings, and “affective empathy,” the ability to respond appropriately. EQ measures both parts.
Earlier studies have shown that some of us are more empathetic than others, and that women, on average, are slightly more empathetic than men. Studies have also shown that autistic people, on average, score lower on the EQ, and that this was because they struggle with cognitive empathy, even though their affective empathy may be intact.
“Finding that even a fraction of why we differ in empathy is due to genetic factors helps us understand those (like autistic people) who struggle to imagine another person’s thoughts and feelings,” said Professor Baron-Cohen.

New Research on the Genetics of Empathy, and How it Relates to Autism

In a first-of-its kind study looking at empathy, researchers have found strong evidence that the ability to read and understand emotions in others simply by looking into their eyes is influenced by our genes.
Published in the journal of <a href="https://www.nature.com/mp/journal/vaop/ncurrent/full/mp2017122a.html">Molecular Psychiatry</a>, the study was led by a team of scientists at the<a href="https://www.cam.ac.uk/affiliations/autism-research-centre"> Autism Research Centre at the University of Cambridge</a>, who combined genetic data from 23andMe with results from a cognitive empathy test developed by the university almost two decades ago called “Reading the Mind in the Eyes.”
<img loading="lazy" decoding="async" src="https://blog-api.23andme.com/wp-content/uploads/2017/05/Mind-in-the-Eyes-Scale_02.jpeg" alt="" class="aligncenter size-full wp-image-25383" width="580" height="235" srcset="https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2017/05/Mind-in-the-Eyes-Scale_02.jpeg 580w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2017/05/Mind-in-the-Eyes-Scale_02-300x122.jpeg 300w" sizes="auto, (max-width: 580px) 100vw, 580px" />
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The researchers found evidence that this important human ability to read, understand and respond to emotions in others — vital for social interactions — is indeed influenced by genetics, and that women were much more adept at discerning emotions than men. The researchers even found a specific genetic variant that influenced that ability in women, an association not found in the opposite sex. In addition, the study found that higher empathy scores were also associated with higher risk for anorexia, more years in school, and openness to new experiences.
The research adds to ongoing studies on the connections between empathy and autism, specifically the ability to infer emotions in others or “cognitive empathy.”
“This is an important step forward for the field of social neuroscience and adds one more piece to the puzzle of what may cause variation in cognitive empathy,” said Warrier.
All of this will help point researchers toward a better understanding of the biological underpinnings for empathy, as well as the phenotypes associated with higher empathy scores. For this study, the researchers used data from more than 89,000 23andMe customers who consented to research.  A smaller cohort of about 1,500 people from<a href="http://www.qimrberghofer.edu.au/our-research/"> the The Queensland Institute of Medical Research&#8217;s (QIMR)</a>, Brisbane Longitudinal Twin Study was also used for this research.
<img loading="lazy" decoding="async" src="https://blog-api.23andme.com/wp-content/uploads/2017/05/Mind-in-the-Eyes-Scale_01.jpeg" alt="" class="aligncenter size-full wp-image-25384" width="583" height="237" srcset="https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2017/05/Mind-in-the-Eyes-Scale_01.jpeg 583w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2017/05/Mind-in-the-Eyes-Scale_01-300x122.jpeg 300w" sizes="auto, (max-width: 583px) 100vw, 583px" />
The genetic variant associated with empathy in women is near the gene LRRN1 on chromosome 3, which is highly active in a part of the human brain called the striatum. Brain scans indicate that this portion of the brain may play a role in cognition empathy, but more study is needed to understand this potential connection.
Warrier worked on this study with Professor Simon Baron-Cohen, director of the Autism Research Centre at the University. Also working on this research was <a href="https://research.pasteur.fr/en/member/thomas-bourgeron/">Professor Thomas Bourgeron</a>, at the University Paris Diderot and the Institut Pasteur. 
“We are excited by this new discovery, and are now testing if the results replicate, and exploring precisely what these genetic variants do in the brain, to give rise to individual differences in cognitive empathy,” said Professor Baron-Cohen.
While the study offers important insight into genetic influences on empathy, there are other important influences that go beyond biology.
“We should not lose sight of other important social factors such as early upbringing and postnatal experience,” said Professor Bourgeron.

The Genetics of Empathy

Each year at this time 23andMe puts together a list of the most interesting genetic findings of 2013. We’re doing that again but with a twist.<img loading="lazy" decoding="async" src="https://blog-api.23andme.com/wp-content/uploads/2011/12/top10ten-266x300.jpg" alt="top10ten" class="alignright size-medium wp-image-10750" width="266" height="300" srcset="https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2011/12/top10ten-266x300.jpg 266w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2011/12/top10ten.jpg 306w" sizes="auto, (max-width: 266px) 100vw, 266px" />
We want to include in our list a few things that aren’t findings or discoveries, but clearly, these stories have had a huge impact on the field of genetics. The fact that these stories made such a big splash beyond the world of science and health reporting illustrates how important genetics has become for everyone.
As far as research goes, in the last year, we’ve seen the continued rapid pace of discovery in genetic sciences. These new findings have included research into the biology of disease, mental illness and new insights into our understanding of human evolution. Researchers here at 23andMe are also a part of this push to understand not just the human story, but the biology of disease and the role genetics plays in our lives.
So let’s take a quick look back at the last year and 23andMe’s list of the Top Ten Genetic Stories of 2013.
<h6> THE ANGELINA EFFECT<img loading="lazy" decoding="async" src="https://blog-api.23andme.com/wp-content/uploads/2013/12/Angelina-image-196x300.jpg" alt="46th New York Film Festival &quot;Changeling&quot; Premiere - Inside Arrivals" class="alignright size-medium wp-image-20131" width="173" height="265" /></h6>
Angelina Jolie’s<a href="https://www.nytimes.com/2013/05/14/opinion/my-medical-choice.html"> revelation</a> that she underwent a double prophylactic mastectomy after learning she had a mutation in the BRCA1 gene, brought genetic screening into sharp focus for everyone. In making her difficult choice, she took into consideration her family history – her mother died of ovarian cancer (also associated with BRCA1 gene mutation) and her aunt also had breast cancer   – her ancestry and her age. Going public with her story also offered comfort to many women facing similar choices.
<h6>EWWW</h6>
It probably wasn’t what Walt Whitman<a href="http://www.daypoems.net/plainpoems/1900.html"> meant</a>, but indeed we all “contain multitudes.” Our bodies are host to literally trillions of microorganisms that make up the “human microbiome,” and those organisms play a very important but not fully understood role in our health. There is also a link between the make-up of that microbiome and the genetic variation of our immune systems, which is another thing we haven’t yet fully figured out. But even without fully understanding how these all interrelate, doctors have started to use these important microorganisms to treat illnesses. Early in the year, the New England Journal of Medicine published a study that followed 16 patients who were treated for a severe gut infection with a<a href="https://www.nature.com/news/faecal-transplants-succeed-in-clinical-trial-1.12227"> fecal transplant.</a> While it might be something you’d rather not talk about over dinner, the treatment of the Clostridium difficile infection worked in 15 of the 16 patients.
<h6>FIVE MENTAL ILLNESSES SHARE A COMMON GENETIC LINK</h6>
A<a href="http://www.thelancet.com/journals/lancet/article/PIIS0140-6736%2812%2962129-1/fulltext"> study published in early 2013</a> found that five very distinct psychiatric disorders share an association with some variants in genes that control signaling in the brain. The large study looked at schizophrenia, bipolar disorder, autism, major depression and attention deficit hyperactivity disorder. Although these are very different conditions, the findings may help researchers better understand the underpinnings of these very different illnesses. Two of the four variants involve calcium channels, integral for signaling within the brain.
<h6 dir="ltr">NOTHING TO SNEEZE AT<img loading="lazy" decoding="async" src="https://blog-api.23andme.com/wp-content/uploads/2010/03/allergy.jpg" alt="allergy" class="alignright size-full wp-image-6151" width="198" height="176" /></h6>
There’s an ongoing debate about the interplay between genetics and the environment in why there has been an apparent increase in the rate of allergies. There are many theories offered to explain this including the “<a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2841828/">hygiene hypothesis</a>,” which suggests that an increasingly sanitized environment inhibits the development of the immune system.  Another theory is that increased exposure to chemicals and pollutants are the culprits. The rate of <a href="http://www.jacionline.org/article/S0091-6749%2805%2901314-X/abstract">allergies</a> has more than<a href="https://www.cdc.gov/nchs/data/databriefs/db10.htm#howdoes"> doubled over the last decade</a>.   While this increase is pointing to environmental factors, genetics is an important component.
A study done by 23andMe scientists and researchers at the University of Bristol’s<a href="http://www.bristol.ac.uk/alspac/"> Avon Longitudinal Study of Parents and Children (ALSPAC)</a> in the UK found <a href="https://mediacenter.23andme.com/press-releases/allergies_2013">new genetic associations for asthma and allergies</a>. It was the largest genome-wide association study ever conducted on common allergies with data from more than 53,000 people. The study showed that there are also common genetic variants underlying allergies to cats, pollen and dust mites
<h6>HUMAN GENES CAN’T BE PATENTED</h6>
Not long after Angelina’s revelation, the Supreme Court unanimously decided to bar the patenting of human genes. The case involved Myriad Genetics, which has long held patents for breast and ovarian cancer screening. What’s not so clear from the Supreme Court’s decision is what sort of impact this decision will have on research and innovation. While several companies almost immediately jumped into BRCA testing, legal challenges by Myriad to   stop those efforts quickly followed, leaving more doubt about how this will all play out.
<h6>THE WAY BACK<img loading="lazy" decoding="async" src="https://blog-api.23andme.com/wp-content/uploads/2013/05/neanderthal.jpg" alt="neanderthal" class="alignright size-full wp-image-18144" width="150" height="270" /></h6>
Scientists extracted DNA from a 400,000-year-old thigh bone found buried in a Spanish cave, known as<a href="https://www.nature.com/nature/journal/vaop/ncurrent/full/nature12788.html"> Sima de Los Huesos, or Pit of Bones.</a>  Apart from the big deal of extracting genetic material from a really, really old bone – the oldest human DNA recovered yet – the find also gives us more information about human evolution, namely that it’s not as linear as some have thought. The DNA in the bone resembled that of ancient humans known as Denisovan.
Because of the time frame and the location, many had thought the bones would be from Neanderthals. The Denisovan DNA was a bit of a head-scratcher. Previous finds placed Denisovans in Siberia and only at about 80,000 years ago. Clearly, this adds more nuances to the story of human evolution. We can also add more pieces to that understanding after another DNA find this year. DNA from the 24,000-year-old skeletal remains of a boy buried near Lake Baikal in Siberia, has also altered researchers&#8217; view of the migration patterns of early Europeans.
The DNA matched not just with Western Europeans but with Native Americans. This suggests that the earliest people to settle the Americas were<a href="http://www.sciencemag.org/content/342/6157/409.full"> a mix of both populations.</a> While previous research has suggested that Native Americans descended from people who migrated from Siberia, this overlap with early Europeans is new. It also suggests that during the last Ice Age, people from Europe had migrated farther east than previously thought.
<h6>ALZHEIMER’S SEQUENCE DATA – CHAPTER ONE</h6>
The more information we can collect from people with the disease, the better we can understand them. Researchers working on Alzheimer’s disease got a huge boost in their efforts this year after the first batch of genetic data was<a href="http://www.nih.gov/news/health/dec2013/nhgri-02.htm"> made available</a> as part of the<a href="https://www.niagads.org/adsp/"> Alzheimer&#8217;s Disease Sequencing Project</a>. The project, conducted by the National Institutes of Health, makes available full genome sequence data on 410 people with Alzheimer’s. The hope is that by offering this information to a wide range of researchers, it will open up the possibility of new discoveries.
<h6>SHARING DATA<img loading="lazy" decoding="async" src="https://blog-api.23andme.com/wp-content/uploads/2009/06/atcg-200x200.jpg" alt="DNA code analysis" class="alignright size-thumbnail wp-image-3837" width="200" height="200" /></h6>
Hundreds of institutions worldwide are currently doing clinical and genetic research. If you could share that data and standardize how it is reported, you could make it that much more useful. That’s exactly what more than 70 medical, research and advocacy organizations did this year, the National Institutes of Health among them. They all agreed to set up a system<a href="https://www.broadinstitute.org/news/globalalliance"> to share genetic and clinical information</a>. By creating a database of genetic variation and health information, it would offer researchers, and doctors, a powerful resource for discovery.
Illustrating the power of shared data, using data from the Electronic Medical Records Genomics Network<a href="https://www.genome.gov/27540473"> (eMERGE</a>) for short – researchers have identified dozens of new variants linked to diseases ranging from skin cancer to anemia. The eMERGE data set allowed researchers to search by gene variant to find associated conditions. As the database grows it will allow researchers to discover connections between seemingly unrelated diseases and genetic variants.
The power of big datasets that include not just genetic information but also phenotypic information, is part of what 23andMe is all about. This year 23andMe researchers leverage our database and certain phenotypes to  functionally classify different genetic associations. our researchers presented some of our findings on this at the ASHG conference this year in Boston. Their findings show that on occasion, a single genetic variant will be associated with multiple different phenotypes. So for example, in autoimmune diseases, a single SNP influences multiple different diseases. Sometimes these shared associations are more surprising, such as the genetic association shared by both<a href="https://blog.23andme.com/health-traits/23andmes-latest-publication-shines-light-on-male-pattern-baldness-and-unexpected-associations-with-disease/"> Parkinson’s disease and baldness</a>. We’ve also found correlations between breast cancer and breast size, body mass index and food choice, and hair color and skin cancer.
<h6>MY, WHAT LONG TELOMERES YOU HAVE</h6>
Several papers this year indicate that genetic variants in telomere genes (such as TERT, TERC, POT1, etc.) not only influence the length of telomeres, which in turn is a good indicator of longevity, but those variants are also associated with certain cancers. Researchers in several different Genome-Wide Association Studies have found links to cancers such as multiple myeloma,<a href="https://www.ncbi.nlm.nih.gov/pubmed/23535731"> breast and ovarian cancer</a>, testicular cancer,<a href="https://www.ncbi.nlm.nih.gov/pubmed?cmd=retrieve&#038;list_uids=23143601&#038;dopt=citation"> lung cancer,</a> and chronic<a href="https://www.nature.com/ng/journal/v45/n5/full/ng.2584.html"> lymphocytic leukemia</a>.
<h6>23ANDME AND THE FDA</h6>
It’s not the kind of news we like, but there’s no way for us to do a roundup of the year&#8217;s big stories without mentioning that the FDA in December ordered 23andMe to stop offering new consumers access to their health-related genetic tests, while the company moves through the FDA’s regulatory review process. 23andMe remains committed to being a pioneer in the genetics revolution and has made its work with the FDA its top priority.
Making it all work will be good not just for the FDA and 23andMe, but for the future of the direct-to-consumer genetic testing industry. Individuals who want to understand their genetics will win too – that’s everyone’s goal. Here’s to 2014.

This Year’s Top Ten Genetic Findings of 2013

<img loading="lazy" decoding="async" class="alignright size-thumbnail wp-image-15595" alt="DNA-bases" src="https://blog-api.23andme.com/wp-content/uploads/2012/09/DNA-bases-200x200.png" width="200" height="200" />By Amick B. 
Research shows a strong genetic basis for autism, but for years scientists have been<a href="https://blog.23andme.com/health-traits/autism-study-reveals-no-genetic-associations/"> unable</a> to pinpoint the specific genetic variants associated with the condition, which may affect as many as one in 88 children in the United States.
<h6>Mitochondrial DNA and Autism</h6>
For some time now researchers have speculated that mitochondrial DNA (mtDNA) may be involved in autism.  Mitochondrial DNA , which is passed down from mother to child, is found in the cell&#8217;s mitochondria – distinct structures that act as a power plant for the cells by converting oxygen and simple sugars into readily-usable energy. Scientists have hypothesized that byproducts or problems with this process might be related to the development of autism spectrum disorders.
A recent study, however, suggests that genetic variants in mtDNA, also known as mito, may not be as important as some had supposed.  The researchers, led by Athena Hadjixenofontos and Jacob  McCauley from the University of Miami, considered mtDNA from nearly 1300 individuals from various ancestral backgrounds with autism spectrum disorders.  
<h6>No Significant Associations</h6>
They looked at both associations with mitochondrial haplogroups as well as individual variants within the mtDNA.  In both cases, they came up empty-handed. The mito was mightily disappointing.
Although no significant associations resulted from this study, the mitochondrial genome remains an intriguing potential path toward further investigation into the genetics of disorders on the spectrum.  
It may be that with larger sample sizes they may find that mtDNA plays an important role in autism genetics after all.  Or, it may be that with further research they will be able to conclusively rule out the role of mtDNA.  
Either way, we&#8217;ll come closer to understanding this common condition.

Mito Mightily Disappoints Autism Researchers

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Researchers have long believed that genetics put some people at higher risk for mental illness than others, but exactly which genes are involved has remained a mystery. Even very large studies have come up with relatively few insights into the genetics of mental illness.
But a study <a href="http://www.thelancet.com/journals/lancet/article/PIIS0140-6736%2812%2962129-1/fulltext" target="_blank" rel="noopener noreferrer">published</a> last week in The Lancet is shedding some light on the connection between genetics and mental illness. The study is the largest mental illness study done to date, and used genetic data from over 60,000 people of European ancestry.
The scientists, led by Dr. Jordan Smoller from the Massachusetts General Hospital in Boston, looked at five different forms of mental illness: autism spectrum disorder, bipolar disorder, attention deficit-hyperactivity disorder, major depression disorder, and schizophrenia. They found four different genetic associations with mental illness in general, and surprisingly they discovered that three of the four associations were involved in all five conditions. This means that the same genetic variants involved in depression may also be involved in schizophrenia.  This genetic similarity between different forms of mental illness was suspected from previous studies in which twins would have different forms of mental illness.
Another interesting aspect of this new study was the importance of calcium channels. Calcium is important for muscle contractions and heart beats, and calcium channels are gates that let calcium in and out of our cells. Two of the four genetic variants that the researchers found occur in genes that encode these calcium channels, suggesting that calcium channels may also be important for mental health.
Sometimes research discoveries seem too removed from our day-to-day life to matter.  Yet this new insight into calcium channels could lead to new treatments, and new treatments would mean good news for millions.  During the course of this year, it is estimated that one in ten of us will suffer from a mood disorder, such as depression or bipolar disorder.  If it’s not you, it may be someone you know.  That makes this study pretty exciting for us all.
<img loading="lazy" decoding="async" class="alignright size-full wp-image-17678" title="MentalIllness" src="https://blog-api.23andme.com/wp-content/uploads/2013/03/MentalIllness2.jpg" alt="" width="593" height="316" srcset="https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2013/03/MentalIllness2.jpg 791w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2013/03/MentalIllness2-300x160.jpg 300w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2013/03/MentalIllness2-768x409.jpg 768w" sizes="auto, (max-width: 593px) 100vw, 593px" />This graph shows the prevalence of different forms of mental illness in US adults in any given year. Statistics are from <a id="internal-source-marker_0.19513093507326507" href="http://www.nimh.nih.gov/health/publications/the-numbers-count-mental-disorders-in-america/index.shtml#MajorDepressive" target="_blank" rel="noopener noreferrer">NIMH</a>. 
 SNPwatch gives you the latest news about research linking various traits and conditions to individual genetic variations. These studies are exciting because they offer a glimpse into how genetics may affect our bodies and health; but in most cases, more work is needed before this research can provide information of value to individuals. For that reason it is important to remember that like all information we provide, the studies we describe in SNPwatch are for research and educational purposes only. SNPwatch is not intended to be a substitute for professional medical advice; you should always seek the advice of your physician or other appropriate healthcare professional with any questions you may have regarding diagnosis, cure, treatment or prevention of any disease or other medical condition.

The Genetics of Mental Illness

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Take a moment to look back at the ten most interesting and significant genetic findings of 2012 or at least the ones that drew our attention.
In the last 12 months we’ve seen huge strides in genetic research giving us new insight into serious conditions such as Alzheimer’s as well as new treatments for cystic fibrosis. And in the last year scientists have made huge leaps in our understanding of the human genome itself with the culmination of a massive study of the so-called uncharted non-coding portions of our DNA – the ENCODE project.
Researchers at 23andMe continue to contribute to some of these important findings with groundbreaking work on the relative importance of family health history versus genetics when determining disease risk and a new method to screen for the genetic risk for certain types of blood disorders.
It’s been another great year of discovery and here’s our top ten.
<img loading="lazy" decoding="async" class="alignright wp-image-5677 size-full" title="alzheimers" src="http://35.88.189.111/wp-content/uploads/2009/12/alzheimers.jpg" alt="" width="435" height="310" srcset="https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2009/12/alzheimers.jpg 435w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2009/12/alzheimers-300x214.jpg 300w" sizes="auto, (max-width: 435px) 100vw, 435px" />
1) &nbsp;A Genetic Variant Protective Against Alzheimer’s Disease – The T version of rs63750847 &nbsp;– also known as the A673T variant in the APP gene – was associated with about five times lower odds of <a href="https://www.ncbi.nlm.nih.gov/pubmed?cmd=Search&amp;db=pubmed&amp;term=22801501">Alzheimer&#8217;s</a>. While this is a very rare variant – only about one in 10,000 people of European descent have it – the research, done by the Icelandic company deCODE Genetics in association with Genentech, adds more insight into the development of the disease. Many mutations in the APP gene actually cause Alzheimer’s through an overproduction of beta amyloid protein in the brain (a hallmark of Alzheimer’s), but the protective variant appears to do the opposite, according to the study. New drugs built on this finding could help protect against Alzheimer’s, or even the mental ravages of normal aging. 23andMe does offer customers reports on their own Alzheimer’s risk based on the more common APOE variant, as well as a report on this protective APP variant.
<img loading="lazy" decoding="async" class="aligncenter wp-image-15558 size-full" title="encode" src="http://35.88.189.111/wp-content/uploads/2012/09/encode.jpg" alt="" width="574" height="334" srcset="https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2012/09/encode.jpg 574w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2012/09/encode-300x175.jpg 300w" sizes="auto, (max-width: 574px) 100vw, 574px" />
2) &nbsp;ENCODE Project Creates a Map of the Uncharted Areas of the Genome – Much of the work in genetics has been focused on the areas in our DNA that code for proteins, but this is a very small part – just 1 percent – of our genome. The<a href="https://www.wired.com/wiredscience/2012/09/encode-human-genome/"> ENCODE project</a>, which has enlisted more than 400 scientists over several years, is attempting to map the rest of it, the so called<a href="https://blog.23andme.com/news/a-map-of-the-uncharted-genome/"> “dark matter” of the genome</a>. What they’ve created is the foundation of a sort of encyclopedia of the functions of many of these uncharted areas of the genome. It’s a resource that will be used by many scientists in the years to come.
3) &nbsp;Noninvasive Prenatal Sequencing – Two separate research groups reported within weeks of each other that they had<a href="https://blog.23andme.com/health-traits/noninvasive-sequencing-of-a-human-fetus/"> successfully sequenced a human fetus</a> and done so noninvasively. The breakthrough offers an opportunity for earlier prenatal screening than currently offered with amniocentesis or chorionic villous sampling (CVS) without the same risks for a developing fetus.
4) &nbsp;New insights into a group of rare blood disorders known as MPNs – In less than a year, 23andMe recruited a 1,000-person cohort with a group of rare blood disorders known as myeloproliferative neoplasms, or MPNs. Within months of reaching that goal we began reporting our<a href="https://blog.23andme.com/23andme-research/novel-genetic-findings-for-myeloproliferative-neoplasms/"> new findings</a>. Among them were replications of known genetic associations with the disease as well as new ones including an association between these conditions and variants in the TERT and ATM genes.
<img loading="lazy" decoding="async" class="aligncenter wp-image-6487 size-full" title="neanderthal_bones" src="http://35.88.189.111/wp-content/uploads/2010/05/neanderthal_bones.jpg" alt="" width="350" height="421" srcset="https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2010/05/neanderthal_bones.jpg 350w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2010/05/neanderthal_bones-249x300.jpg 249w" sizes="auto, (max-width: 350px) 100vw, 350px" />
5) &nbsp;New Insights into Human Origins and Evolution – Several different studies highlight ongoing research on our early ancestors and the evolution of modern humans. Beyond the compelling tale of our early ancestors, the journey out of African and the intermixing with Neanderthals and Denisovans, the new research also gives us insight into the<a href="https://www.wired.com/wiredscience/2012/11/recent-human-evolution-2/"> significance of rare genetic variants</a>.
6) &nbsp;Family Medical and Genetics Used Together to Predict Disease – 23andMe <a href="https://blog.23andme.com/23andme-research/using-genetics-and-family-history-for-health/">developed a model</a> to show that both family history and genetic tests have strengths in predicting disease risks, but when used together they provide the best predictor for disease.
&nbsp;7) &nbsp;Older Dads’ Biological Clocks – For a long time prospective fathers could wile away the years without much worry about when to have kids, while prospective moms were constantly checking their ticking biological clocks.<a href="https://www.nature.com/nature/journal/v488/n7412/full/nature11396.html"> A study</a> may turn the tables a bit, pushing men to think a little more about how long they wait to start a family. The study says that as men grow older the number of de novo mutations they<a href="https://blog.23andme.com/health-traits/for-older-dads/"> pass onto their children increases</a>, and preliminary studies suggest that the more de novo mutations passed onto a child the higher the risk that child could develop certain types of conditions, such as autism and schizophrenia. That said becoming a dad can actually be good for you. There’s evidence linking <a href="https://blog.23andme.com/health-traits/ah-fatherhood-dirty-diapers-skinned-knees-and-healthier-hearts/">fatherhood to healthier hearts.</a>
8) &nbsp;Breast Size Matters, But Not How You Think – Researchers at 23andMe found that genetic factors influence breast size and that in turn these factors are connected to the genetics of breast cancer.
&nbsp;9) &nbsp;New Treatment for Cystic Fibrosis – &nbsp;Early in 2012 the FDA approved ivacaftor (Kalydeco ®) as a new treatment for cystic fibrosis, one of the most common recessively inherited diseases. The drug<a href="https://online.wsj.com/article/SB10000872396390444024204578046911440223842.html?mod=WSJ_TechInnovationAwards1012_MiddleSecondSummaries%20."> developed by Vertex Pharmaceuticals Inc</a>. is the first treatment that targets one of the underlying causes of cystic fibrosis – a specific genetic mutation – rather than its symptoms.
10) &nbsp;Autism Study Reveals No Genetic Associations – It may be strange to <a href="https://blog.23andme.com/health-traits/autism-study-reveals-no-genetic-associations/" target="_blank" rel="noopener noreferrer">point to a study that finds no genetic associations</a>, but sometimes an absence of evidence can hint toward new routes of study. Cases of Autism spectrum disorders – which run the gamut from mild to severe impairment and include autism, Asperger syndrome and other disorders – have become increasingly common in the U.S. Why that is, is not so easy to discern. The lack of an association doesn’t mean that genetics isn’t important. In fact twin studies suggest that autism is at least moderately heritable, but it may be that genetic variations play a smaller role than rare mutations or copy number variation in the risk of a person developing autism.

Top Genetic Findings of 2012

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For a long time prospective fathers could wile away the years without much worry about when to have kids, while prospective moms were constantly checking their ticking biological clocks.
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<div>A<a href="https://www.nature.com/nature/journal/v488/n7412/full/nature11396.html"> recent study</a> may turn the tables a bit. It may push men to think a little more about how long they wait to start a family.The study by DeCODE in Iceland shows that each year a man delays fatherhood he increases the number of new genetic mutations that he passes on to his children.
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<h2>A Calculation</h2>
<div>These “de novo” mutations are not ones that the father was born with. Therefore they are unrelated to any previous family history or condition. They occur spontaneously in the father’s sperm cells.Using the data from the study, 23andMe’s Emily Chang lead the team that  created a simple tool that uses a man’s age to calculate the number of mutations he might pass on to his children.
<img loading="lazy" decoding="async" class="aligncenter wp-image-15995 size-full" title="mutation small" src="http://35.88.189.111/wp-content/uploads/2012/09/mutation-small.jpg" alt="" width="253" height="406" srcset="https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2012/09/mutation-small.jpg 253w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2012/09/mutation-small-187x300.jpg 187w" sizes="auto, (max-width: 253px) 100vw, 253px" />
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<div>So what does the number mean?</div>
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<div>The<a href="https://www.nytimes.com/2012/08/23/health/fathers-age-is-linked-to-risk-of-autism-and-schizophrenia.html"> implication from the study</a> is that the longer a man waits the more he increases the chances his child might develop certain kinds of conditions, such as autism. While the risk may increase, it is still very low.Also, keep in mind that despite the name, mutations are not necessarily bad. In fact, these different spellings within a person’s genetic code are largely benign. Some may even be beneficial and lead to long term genetic diversity among people.
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<h2>A Risk for Autism?</h2>
Science writer Alok Jha pointed out in a<a href="http://www.guardian.co.uk/science/2012/aug/22/older-fathers-genetic-mutations-research"> piece in the Guardian</a> that a single mutation in the APP gene actually protects against Alzheimer’s disease. It also helps people live longer. At the same time, some preliminary studies suggest that the more de novo mutations passed onto a child the higher the risk that child could develop certain types of conditions, such as autism and schizophrenia.
<div>Or as lead author Kari Stefansson, deCODE’s chief executive,<a href="https://www.nature.com/news/fathers-bequeath-more-mutations-as-they-age-1.11247"> told Ewen Callaway at Nature</a>:</div>
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“The older we are as fathers, the more likely we will pass on our mutations. The more mutations we pass on, the more likely that one of them is going to be deleterious.”
For women, who pass on other risks to their children with age, the number of de novo mutations a mom passes on to a child is constant at about 14. The number of new mutations a father passes to a child goes up by two each year. That means that a 50-year-old new father might pass on about 65 new mutations to his child. A father half his age would pass on about 35 mutations. The reason the number of de novo mutations women and men pass on to their children is so different is because women are born with all their eggs. Men on the other hand produce sperm throughout their lifetime, offering more opportunities for mutations to occur.
This doesn’t necessarily mean that men should start having kids or having their sperm frozen right out of college. But it does add more information for prospective fathers to consider. It also gives us a little more understanding about complex conditions like autism.
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Older Dads

<img loading="lazy" decoding="async" class="aligncenter size-medium wp-image-15055" src="https://blog-api.23andme.com/wp-content/uploads/2012/08/autisticSign-200x300.jpg" alt="" width="200" height="300" srcset="https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2012/08/autisticSign-200x300.jpg 200w, https://blog.pub.us-west-2.prd.23andme.us/wp-content/uploads/2012/08/autisticSign.jpg 283w" sizes="auto, (max-width: 200px) 100vw, 200px" />
Autism spectrum disorders include everything from the relatively mild Asperger syndrome (characterized by more mild social and language impairments) to full-fledged autism (characterized by severe social and communicative handicaps, limited interests, and repetitive behaviors).
<h2>The Genetics of Autism</h2>
Austism is relatively common, and in the United States it is estimated that one out of every 54 boys is affected (the frequency in girls is considerably lower, averaging one affected girl out of every 252).
Although genetics certainly plays a role in these conditions, exactly how is not fully understood, and this newest  <a href="https://www.ncbi.nlm.nih.gov/pubmed/22843504" target="_blank" rel="noopener noreferrer">study</a>, led by Richard Anney (Trinity College of Dublin) and Bernie Devlin (University of Pittsburgh School of Medicine), is the next a long line of scientific inquiries to this point.
Their study, known as the Autism Genome Project (AGP), was conducted in two stages. The first stage of consisted of a genome-wide association study using genetic data from 1400 families affected by autism; the second stage checked the associations discovered in the first stage using the genetic data from an additional 1301 autism-affected families and included another new genome-wide association study which combined the study subjects from both stages.
<h2>A Lack of Common SNPs Associated with Autism</h2>
When all the analyses were said and done, no SNPs (common genetic variations) were significantly associated with austism. Furthermore, when some of the SNPs that had been identified in the first study as possibly associated with autism were tested in the second-stage families, the associations failed to hold up.  This lack of common SNPs associated with autism is both disappointing and enlightening.
Knowledge of what is not true, paradoxically, is knowledge of what is true.  For instance, if I tell you that my pet Tyger is not a dog, you are one step closer to knowing Tyger’s a cat.  Most of science progresses through “not trues” &#8212; the failed hypotheses that bring us closer to real understanding. A perfect example of this mode of scientific progress is this recent genetic study.   Their lack of findings was quite a finding.
The fact that no SNPs were associated with autism in such a large study suggests that the effect of any one common SNP is quite small. Even when all the SNPs were used together to predict whether a study subject would have autism, the model explained less than 1 percent of differences in risk for the condition.
<h2>Heritability</h2>
The fact that these common SNPs have little power to predict autism does not mean that genetics is unimportant.
Twin studies suggest that autism is at least moderately heritable, suggesting that genetics does play a role.  This current study’s lack of findings supports the idea that common genetic variations may play a smaller role than rare mutations or copy number variation (the number of copies of a given gene) in autism risk. Thus, the lack of autism associations today has, hopefully, brought us closer to tomorrow&#8217;s discoveries.

Autism Study Reveals No Genetic Associations

<img loading="lazy" decoding="async" class="alignright size-full wp-image-2970" title="autismawareness" src="https://blog-api.23andme.com/wp-content/uploads/2009/03/autismawareness.jpg" alt="" width="141" height="247" />
Researchers have identified <a href="https://blog.23andme.com/articles/snpwatch-connections-between-brain-cells-may-be-key-to-autism-puzzle/" target="_blank" rel="noopener">yet another</a> common genetic variation that appears to be associated with autism.   The results, published this week in the journal <a href="https://dx.doi.org/10.1038/mp.2009.41" target="_blank" rel="noopener">Molecular Psychiatry</a>, show that each copy of an G at in the CACNA1G gene increase the odds of autism in boys (but not girls) by about 2.2 times.
But Stanley Nelson, senior author of the study and a 23adMe scientific advisor, points out that the G version of this SNP is actually fairly common.
&#8220;Most people with the risk genotype will not develop autism.&#8221;
For more on this story:
<ul>
<li><a href="https://www.bloomberg.com/apps/news?pid=20601124&amp;sid=aLhQfJuxV8.s&amp;refer=home" target="_blank" rel="noopener">Gene May Offer Clue Why Autism Risk Is Fourfold Higher in Boys</a></li>
<li>A Genetic Clue to Why Autism Affects Boys More</li>
<li><a href="http://newsroom.ucla.edu/portal/ucla/ucla-scientists-identify-new-gene-92513.aspx" target="_blank" rel="noopener">UCLA scientists identify new gene linked to autism risk</a></li>
</ul>

Autism