<img loading="lazy" decoding="async" class="aligncenter size-medium wp-image-3613" title="Grandparent and daughter" alt="" src="https://blog-api.23andme.com/wp-content/uploads/2009/05/istock_000004109962xsmall-300x245.jpg" width="300" height="245" srcset="https://blogcms.23andme.com/wp-content/uploads/2009/05/istock_000004109962xsmall-300x245.jpg 300w, https://blogcms.23andme.com/wp-content/uploads/2009/05/istock_000004109962xsmall.jpg 383w" sizes="auto, (max-width: 300px) 100vw, 300px" />
<a href="http://www.23andme.com/topics/health-predispositions/hereditary-hemochromatosis/">Hereditary hemochromatosis</a> is a common genetic condition that makes a person more prone to absorbing too much iron. Premenopausal women are largely protected from iron overload because of menstruation and pregnancy, but typically around menopause some women begin to experience symptoms of the condition.
A <a href="http://annals.org/article.aspx?articleid=710670">study</a> published in the late 1990’s with 176 women and 176 men with hemochromatosis, matched by age, found that a significant number of the women suffered serious complications from hemochromatosis, and developed their first symptoms only a little later than the men. On average, the women in the study showed symptoms around age 50, while the men showed signs nearly two years earlier. Roughly half of the women had stopped menstruating at the time of diagnosis, but the other half were technically premenopausal at diagnosis. There was some evidence that women who stopped menstruating before the age of 50 had higher levels of iron in their bodies.
For certain conditions*, like cirrhosis and diabetes, rates were higher in men, but for others, like fatigue and arthritis, rates were higher in women. Roughly 94 percent of the women, versus 100 percent of men, had abnormal measures of iron stores in the body.
<div style="float: right; text-align: justified; width: 200px; padding: 15px; border: 1px solid #ccc; margin-left: 10px;">Women and Men Have the Same Genetic Risk for Hemochromatosis 
Hereditary hemochromatosis affects women and men equally with respect to how the condition is inherited: you must inherit a mutated gene from each parent to have the condition and the gene involved in most forms of hereditary hemochromatosis, the HFE gene, is not located on the sex chromosomes. (This condition is autosomal recessive.) 
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Thus, the results from this study suggest that women can suffer overt symptoms of hereditary hemochromatosis and at roughly the same age as men. And once a woman goes through menopause and loses her natural way of expelling iron, she appears to have more or less the same risk as a man for suffering serious complications including arthritis and liver disease.
For most women menopause is associated with <a href="http://my.clevelandclinic.org/disorders/menopause/hic_menopause_the_short-term_effects_and_long-term_risks.aspx">various changes in health</a>. In the short term women can attest to unpleasantries that result from drops in estrogen levels. High on the list are hot flashes, changes in sex drive, and mood changes. But there are also serious long term risks for conditions like osteoporosis and heart disease. For women with hereditary hemochromatosis, increased risk for absorbing too much iron should also be added to the list. Women should take note that the symptoms of menopause and hemochromatosis can sometimes overlap, for instance fatigue is common to both.
Whether before or after menopause, it’s important for women with hereditary hemochromatosis to monitor the iron levels in their body. Physicians can order blood tests to measure transferrin saturation and serum ferritin levels in blood, which together provide a good picture of iron absorption and storage in the body. If these markers are elevated, additional testing to determine the impact on organs may also be warranted.
*Liver cirrhosis occurred in ~14 percent of the women and 26 percent of the men; diabetes occurred in ~7 percent of the women and ~16 percent of the men; fatigue occurred in ~65 percent of the women and 42 percent of the men; arthritis occurred in ~45 percent of the women and ~35 percent of the men.

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23andMe Blog

23andMe Blog Team

Hemochromatosis in Women Before and After Menopause

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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://blogcms.23andme.com/wp-content/uploads/2012/09/mutation-small.jpg 253w, https://blogcms.23andme.com/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="alignright size-thumbnail wp-image-5677" title="alzheimers" alt="" src="https://blog-api.23andme.com/wp-content/uploads/2009/12/alzheimers-150x150.jpg" width="150" height="150" srcset="https://blogcms.23andme.com/wp-content/uploads/2009/12/alzheimers-150x150.jpg 150w, https://blogcms.23andme.com/wp-content/uploads/2009/12/alzheimers-271x271.jpg 271w" sizes="auto, (max-width: 150px) 100vw, 150px" />
In honor of World Alzheimer’s Day, we’re linking to a few posts and stories about the disease. Alzheimer’s disease is the most common form of dementia and affects more than 35 million people worldwide.
23andMe first began allowing customers to learn about their genetic risk for late-onset Alzheimer’s disease a little more than a year ago. We report on variants of the<a href="https://www.23andme.com/health/alzheimers/"> APOE</a> gene (e2, e3, and e4) and provide a risk estimate for the disease for customers with European ancestry. The 23andMe report also includes detailed background information on Alzheimer’s including other known risk factors for the disease, such as obesity and high cholesterol.
Although some are critical of giving people access to this information, many people say that despite their fear of Alzheimer’s they<a href="https://www.washingtonpost.com/national/health-science/despite-fears-of-alzheimers-many-would-like-to-know-their-risk-for-the-disease/2012/08/10/438eb3ba-6a2c-11e1-acc6-32fefc7ccd67_story.html"> would rather know</a> their risk than remain in the dark about the danger. For some knowing their APOE status and Alzheimer’s risk may encourage them to engage in <a href="http://well.blogs.nytimes.com/2012/01/18/how-exercise-may-keep-alzheimers-at-bay/">activities to stave off</a> the disease, or prompt them to participate in clinical research that could lead to more information about the causes and possible cures for Alzheimer’s.
Recently, scientists discovered a rare genetic variant that may be protective against the disease. In people of Icelandic descent, the T version of the variant (also known as the A673T variant in the APP gene) was associated with about five times lower odds of Alzheimer’s. This finding was <a href="https://www.nature.com/nature/journal/v488/n7409/abs/nature11283.html">first reported in the journal Nature</a> over the summer.
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World Alzheimer’s Day

<img loading="lazy" decoding="async" class="alignright size-medium wp-image-6445" title="elderly_1" src="https://blog-api.23andme.com/wp-content/uploads/2010/04/elderly_1-300x199.jpg" alt="" width="300" height="199" srcset="https://blogcms.23andme.com/wp-content/uploads/2010/04/elderly_1-300x199.jpg 300w, https://blogcms.23andme.com/wp-content/uploads/2010/04/elderly_1.jpg 425w" sizes="auto, (max-width: 300px) 100vw, 300px" />
A study published in March in the journal <a href="http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0032840">PLoS ONE</a> suggests that having more African ancestry is associated with higher risk for type 2 diabetes.
Type 2 diabetes is one of the most common chronic diseases in the United States, affecting about 26 million people and more than 25% of the population over the age of 65. While most people realize that lifestyle factors like an unhealthy diet and lack of exercise increase the risk of developing the disease, many may not realize that ancestry plays a role, too. In fact, type 2 diabetes strikes non-white ethnic groups at higher rates, with African Americans experiencing the highest rates of all. 
 
Higher rates of obesity and heart disease, and lower socioeconomic status in the African American population certainly contribute to this trend, but, as <a href="http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0032840">this study</a> found, those factors aren’t the whole story. Led by Ching-Yu Cheng and Linda Kao from Johns Hopkins University, the research team analyzed DNA from more than 7,000 African Americans and found that those with the most (&gt; 87.5%) African ancestry had about 33% higher odds of type 2 diabetes compared to those with the least (&lt; 80.5%) African ancestry after accounting for body mass index (BMI) and socioeconomic status.
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See your <a href="https://www.23andme.com/you/ancestry">ancestry breakdown</a> in your 23andMe account.
Not yet a customer? <a href="https://www.23andme.com/store">Visit our store</a>!
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A person’s ancestry can be traced back to various regions of the world (e.g., Europe, Asia, and Africa) using genetic markers that are known to be indicative of those ancestral groups. On average, the African Americans in the study had about 84% African ancestry.
Cheng and Kao’s findings add further support to the idea that differences in disease rates across different populations can be partly explained by ancestry genetics. A previous study looking at <a href="https://blog.23andme.com/articles/the-ancestry-link-for-atrial-fibrillation-risk">atrial fibrillation (a heart rhythm disorder) in African Americans</a> also found that having more African ancestry correlated with higher odds of the condition. Most likely, correlations like these reflect variations in the frequency of many different genetic factors involved in disease. In a few cases, though, individual genetic factors can have greater importance. For example, in East Asians, who have some of the highest rates of esophageal cancer in the world, a specific genetic factor causing the “<a href="https://blog.23andme.com/articles/researchers-warn-that-physicians-need-to-ask-about-alcohol-flushing-to-reduce-esophageal-cancer-risk">alcohol flush</a>” reaction plays a direct role in the development of esophageal cancer.
Studies like this one highlight the complex interplay between ancestry and health in African Americans, the vast majority of whom can trace significant parts of their ancestry back to at least two continents. Combined with <a href="https://www.23andme.com/ancestry/recent/">DNA-based tools</a> that allow people to see their <a href="https://www.23andme.com/dna-ancestry/">ancestral breakdown</a>, health risk assessments that incorporate genetic ancestry may help make healthcare more personalized.

African Ancestry and Risk for Type 2 Diabetes

For back-to-school month we’re running a series of posts on genetic factors that may impact learning. Here we describe a variant that may influence a person’s ability to learn from their mistakes. In a <a href="https://blog.23andme.com/traits-2/back-to-school-smarts-and-genetics/">prior post</a> we discuss a variant linked to non-verbal IQ performance.
<img loading="lazy" decoding="async" class="aligncenter wp-image-15553" title="Avoidance of Errors" src="https://blog-api.23andme.com/wp-content/uploads/2012/09/Avoidance-of-Errors.png" alt="" width="393" height="740" srcset="https://blogcms.23andme.com/wp-content/uploads/2012/09/Avoidance-of-Errors.png 393w, https://blogcms.23andme.com/wp-content/uploads/2012/09/Avoidance-of-Errors-159x300.png 159w" sizes="auto, (max-width: 393px) 100vw, 393px" /><a href="https://blog-api.23andme.com/wp-content/uploads/2012/09/Avoidance-of-Errors1.png"> 
</a><a href="https://blog-api.23andme.com/wp-content/uploads/2012/09/Avoidance-of-Errors.png"> 
</a>Attribution: http://xkcd.com/242/
Why do some people have a hard time learning from their mistakes?
It might have to do with genetics. At least one research study suggests that the tendency to make rewarded choices while avoiding those that receive negative feedback may be influenced by genetics.
In <a href="https://www.ncbi.nlm.nih.gov/sites/entrez?cmd=Search&amp;db=pubmed&amp;term=18063800">this study</a>, 26 German individuals took a test that assessed their ability to prefer &#8220;correct&#8221; choices and avoid &#8220;incorrect&#8221; ones. The authors genotyped the subjects at the SNP , which is thought to affect a gene involved in dopamine signaling. The neurotransmitter dopamine is involved in trial-and-error learning and variations in genes related to dopamine signaling may also affect a person&#8217;s ability to learn.
People with the GG genotype at learned to avoid choices associated with negative feedback relatively easily, while people with the AG or AA genotypes did not learn as well to avoid these &#8220;punished&#8221; choices; in other words, they did not learn from their mistakes. The AG and AA genotypes have also been correlated with up to a 30% reduction in dopamine receptor density in a region of the brain known as the striatum.
( is commonly referred to in the scientific literature as the DRD2 TaqIA polymorphism. The A version of is equivalent to the A1 allele of DRD2 TaqIA, while the G version of the SNP corresponds to the A2 allele.)
 
If you’re looking for a genetic excuse, this is a good one to point to. The next time your spouse is amazed that you left the house again without your phone … or house keys … just say that you’re genetically predisposed to not learn from your mistakes.
The results presented here were obtained with a very small sample size and have not been independently replicated. While the results are intriguing, it’s important to realize that learning is an extremely complex behavior that is also strongly influenced by environment.
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Genetic Differences in Dopamine Receptors and Effect on the Brain 

<img loading="lazy" decoding="async" class="aligncenter wp-image-15614" title="Dopamine receptor polymorphism" src="https://blog-api.23andme.com/wp-content/uploads/2012/09/Dopamine-receptor-polymorphism-300x290.jpg" alt="" width="300" height="290" srcset="https://blogcms.23andme.com/wp-content/uploads/2012/09/Dopamine-receptor-polymorphism-300x290.jpg 300w, https://blogcms.23andme.com/wp-content/uploads/2012/09/Dopamine-receptor-polymorphism.jpg 638w" sizes="auto, (max-width: 300px) 100vw, 300px" />
In a more recent <a href="http://www.jneurosci.org/content/29/12/3695.long">study</a> by the same researchers, 28 German males performed a similar learning task except partway through the experiment the “correct” choice was reversed – the one that used to be right was now wrong. The scientists found that people with at least one A at had a hard time consistently choosing the “correct” response after the reversal even if they had just chosen and been rewarded for that response. Perhaps not surprisingly, the behavior seemed to correlate with differences in brain activity. The researchers imaged the participants’ brains (with <a href="https://en.wikipedia.org/wiki/Functional_magnetic_resonance_imaging">functional magnetic resonance imaging, or fMRI</a>) while they performed the task and saw more signal in GG individuals (A1- in the figure) compared to AG and AA people (A1+ in the figure) in parts of the striatum and ventral midbrain where dopamine receptors are located. A similar correlation between reduced brain activity in dompinergic regions of the brain and impaired ability to “learn from mistakes” was also observed in the original study. Figure from: <a href="https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&amp;retmode=ref&amp;cmd=prlinks&amp;id=19321766">J Neurosci. 2009 March 25; 29(12): 3695—3704. </a>
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Back-to-School: The Genetics of Learning from Your Mistakes

<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://blogcms.23andme.com/wp-content/uploads/2012/09/encode.jpg 574w, https://blogcms.23andme.com/wp-content/uploads/2012/09/encode-300x175.jpg 300w" sizes="auto, (max-width: 574px) 100vw, 574px" />
Editor&#8217;s note: The post has been edited from the original to reflect changes in the product.
We’re a little late to the party, but yesterday a consortium of scientists, who are part of a project called The Encyclopedia of DNA Elements, or<a href="https://www.genome.gov/10005107"> ENCODE</a>, came out with what some are calling a roadmap of the human genome.
<a href="https://www.nature.com/nature/journal/v489/n7414/full/489049a.html">It’s a big party.</a>
More than 400 scientists worked on the project, which was funded by the National Institutes of Health over the last five years at a cost of about $130 million. The announcement came with a blizzard of 30 papers in the journals Nature and Genome Research and many more are expected to come.
There has been some great coverage that explains both the background and gives some context, such as a nice piece by Nature writer<a href="https://www.nature.com/news/encode-the-human-encyclopaedia-1.11312"> Brendan Maher’s</a>. Discovery Magazine blogger Ed Yong did a yeoman’s job of the history of ENCODE’s work and what the future may hold. And <a href="https://www.nytimes.com/2012/09/06/science/far-from-junk-dna-dark-matter-proves-crucial-to-health.html?_r=2&amp;hp">Gina Kolata’s article</a> in the New York Times includes our favorite quote. It came from Eric Lander, president of the Broad Institute, who compared the data to a sort of Google Map of the genome and said it was a stunning resource for researchers.
“My head explodes at the amount of data,” Lander said. 
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Us too, and the challenge is really giving people a sense of what it all means. 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 ENCODE project is an attempt to map the other 99 percent, the uncharted “dark matter” of our genome.
There’s much that’s interesting there it turns out. And the work sheds some light on the importance of what once was labeled “junk DNA.” It turns out, unsurprisingly, that it’s not junk and the data from ENCODE provides evidence that many of those mysterious regions of the genome play important functional roles.
For us at 23andMe the <a href="http://regulomedb.org/">ENCODE data</a> sheds more light on some of the genetic variations (mainly single nucleotide polymorphisms, or SNPs) scientists have associated with health conditions and traits. S
There are many SNPs in the 9p21 region associated with coronary heart disease, and based on the ENCODE data, it appears that this SNP and rs1333047 are the primary functional SNPs. Of the various SNPs in the region, <a href="https://genome.cshlp.org/content/22/9/1748.full">rs10757278 and rs1333047 are likely to affect the binding of transcription factors</a>  – proteins that bind to DNA and regulate the expression of genes. These two SNPs are perfectly correlated in people with European ancestry, and the G version of rs10757278 is associated with higher odds of coronary heart disease in people with European ancestry.
Another example is the SNP rs964184 located near the APOA5 gene, which has also been associated with cholesterol levels. The ENCODE data show that it likely affects binding of transcription factors and results in differences in expression of a &#8220;target&#8221; gene of those transcription factors. The G version of rs964184 is associated with higher odds of coronary heart disease in Europeans.
These examples highlight how this new data can inform the “why” and “how” of genetic associations. Where before scientists often had very little idea which exact SNP was involved and why it was associated with a disease, now we can narrow down the SNPs likely to be responsible and start looking at their biological impact. The ENCODE data show what Kolata describes as at least four million gene switches in our DNA that collectively control how the cells, organs and other tissues in our bodies develop and behave.
Though there’s still much to learn about this newly revealed and incredibly complex genetic circuitry, it’s clear that the data will be a resource for many scientists working in genetics including us here at 23andMe.

A Map of the Uncharted Genome

<img loading="lazy" decoding="async" class="aligncenter size-medium wp-image-15370" title="Classroom Hands picture" src="https://blog-api.23andme.com/wp-content/uploads/2012/08/Classroom-Hands-picture-300x211.jpg" alt="" width="300" height="211" srcset="https://blogcms.23andme.com/wp-content/uploads/2012/08/Classroom-Hands-picture-300x211.jpg 300w, https://blogcms.23andme.com/wp-content/uploads/2012/08/Classroom-Hands-picture.jpg 413w" sizes="auto, (max-width: 300px) 100vw, 300px" />
Editor&#8217;s note: This post has been edited from the original to reflect changes in our product.
If you want to stir up trouble, start talking about genetics&#8217; role in intelligence.
First, there’s the question of what you’re talking about: Is intelligence measured through mathematical skills, problem-solving, perceiving emotions, or a raw score from an I.Q. test?
<h2>Complex Traits</h2>
Not to be glib, but understanding intelligence – how to measure, define, and figure out what can influence it – takes some brainpower. It’s complicated. Innumerable factors influence intelligence – a layered mix of biology and environment. Access to education, your economic well-being, and even the prevalence of parasites in your community impact IQ scores.
That said, there’s good evidence that some differences in measurable intelligence, such as your IQ score, can be chalked up to genetics. While IQ tests don’t consider essential life skills – things like your powers of persuasion or your ability to build consensus and feel empathy – the tests are valuable nonetheless. At the very least, your IQ score is a pretty good predictor for how well you’ll do in school.
<h2>IQ Score Not Always the Right Measure</h2>
As Richard Haier of the University of California at Irvine said to Carl Zimmer in a Scientific American article, IQ score doesn’t tell you everything about how smart someone is.
But it’s like many other measurements that can be useful in the right context.
“When you see your doctor, what’s the first thing that happens? Somebody takes your blood pressure and temperature,” Haier said. “So you get two numbers. No one would say blood pressure and temperature summarize everything about your health, but they are key numbers.”
So, as we begin a series of “Back to School” posts, we’re going to take a moment to look at the genetics surrounding this one measure of intelligence. By the way, there will be a test—actually, three of them—in this series of posts.
<h2>Genetic Factors</h2>
As for measures of intelligence, recent studies estimate that in early childhood about 25-to-40 percent of individual variation in measurable intelligence can be attributed to genetics. In adults, this number increases to about 80 percent.
A study of Dutch families found that the SNP is associated with &#8220;performance IQ&#8221; (i.e., nonverbal IQ). Each A at increased subjects&#8217; performance IQ by an average of three points compared to those with no copies. The authors estimated that this accounts for 3.4% of the variation in performance IQ between people.
While the association between differences in IQ scores is significant, its overall effect is minimal, a difference of just three points on average.
It’s also important to note that no single gene has an inordinate impact on IQ scores. Instead, hundreds of genes impact intelligence with a cumulative impact on IQ scores. In a recent study, researchers <a href="https://www.ncbi.nlm.nih.gov/pubmed/22504419" target="_blank" rel="noopener">found</a> another variant, this one in the HMGA2 gene, that also has a small effect on IQ scores.
Although the HMGA2 gene has been associated with height, it also influences the size of the brain. Researchers also found that the C version of was also associated with a very slight increase in IQ. We wrote about this in the <a href="https://blog.23andme.com/articles/head-size" target="_blank" rel="noopener">Blog in April. </a>

Back to School Smarts and Genetics

<img loading="lazy" decoding="async" class="alignright size-medium wp-image-15308" title="HighlightedGraph" alt="" src="https://blog-api.23andme.com/wp-content/uploads/2012/08/HighlightedGraph-300x298.jpg" width="300" height="298" />Click on the image above for the interactive visualization.
Some things just go together – peanut butter and jelly, cheese and crackers, <a href="https://en.wikipedia.org/wiki/Tango_%26_Cash" target="_blank" rel="noopener noreferrer">Tango and Cash</a>. Other things not so much, or, at least, not until you dig into the connections a little deeper.
In health, the connection between two or more <a href="https://www.23andme.com/dna-health-ancestry/">health conditions</a> is often intuitive. If you grind your teeth, it stands to reason that you would have pain symptoms around the jaw. It makes sense that a person who has eczema might also have other skin conditions like dandruff or psoriasis.
But the connection between other health conditions isn’t always so obvious. Digging into those connections, finding out if they are real, and, if they are real, why they might be related, can tell us a lot of about disease.
With that in mind, we’ve created a visualization of several dozen self-reported health conditions from more than 38,000 members of CureTogether, which<a href="../news/curetogether-with-23andme/" target="_blank" rel="noopener noreferrer"> 23andMe acquired in early July</a>. CureTogether is a free resource for people to share information about diseases and treatments. This kind of data can be helpful to both members interested in comparing their own health issues with others, and researchers looking for a deeper understanding of illnesses.
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“(It) can give insights into the underlying biology of the conditions,” said Emily Chang, a scientist on 23andMe’s Science Content and Curation Team. “Perhaps there are genetic factors or environmental factors that predispose a person to both conditions.”
One condition might be a symptom of the other, but whatever the connection, exploring why two or more conditions might be related is essential.
“Accurate knowledge of a condition&#8217;s symptoms can aid biological understanding and improve diagnosis,” Emily said.
Daniel Reda, CureTogether’s co-founder and now a 23andMe Senior Product Manager worked with Emily to create the visualization. The two compiled more than 4.4 million points of data to show conditions and symptoms that have a statistically strong connection to each other.
“As we accumulate more data, we can replicate this type of analysis and this should help reveal which of the associations may be spurious and which are probably real,” said Daniel.
What Daniel and Emily have created is a sort of Wheel of Conditions. It shows connections between different conditions, diseases, and symptoms. Selecting a condition will highlight other conditions that are most likely to occur in common.
What you’ll see very quickly is that some of the connections, as we’ve said, just go together. Others, at first blush, may make you scratch your head, but digging a little may help explain the connection.
For example, why would anemia have a connection with infertility?
“(It) makes intuitive sense to me from an evolutionary perspective,” said Daniel. “The body would want to avoid the huge energy investment of pregnancy if the blood has potentially insufficient oxygen-carrying capacity. In ancestral times, vitamin deficiency from food scarcity would have caused anemia, so it would make sense for the body to be able to turn off its reproductive potential until conditions improved.”
The wheel also shows some conditions, fibromyalgia, for instance, are hubs for many others.
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Emily suggests that in some cases a condition may have a broad range of symptoms – pain, depression or fatigue – accounting for multiple connections.
“A large number of causes, the large number of symptoms and the difficulty in accurately diagnosing the conditions probably all contribute to many connections between these conditions and others on the chart,” she said.
What’s exciting is that this is just a first step. Integrating 23andMe’s genotypic and phenotypic data may be able to reveal a deeper understanding of the causes of these conditions.
“Hopefully, (it will) lead to more insights,” Emily said. “With a larger database we will be able to be more accurate making connections and also will be able to make more connections. Genotypic information can add still more.”
Combining genetic and phenotype data from these two large data promises to bring new understanding to disease.

Crowdsourcing Health Conditions

You may not think very much about yaks, but Tibetans do.
The domestic yak is crucial for their survival on the harsh Qinghai-Tibetan Plateau. The yak provides meat, milk and, to the distate of many Western travelers, salty yak-butter tea.  Like the people who domesticated it, the yak is tough, thriving at altitudes and with nutritional restrictions which can kill the common cow.
A recent study of the yak genome sheds light on what makes these beasts so well-suited for their hard lives on the high plateaus. The work, published in a recent issue of Nature Genetics, may also help shed light on how humans adjust to high altitude.
The newly <a href="https://www.ncbi.nlm.nih.gov/pubmed/22751099" target="_blank" rel="noopener noreferrer">published</a> yak genome is the work of an international team of researchers headed Qiang Qiu and Jianquan Liu at the Lanzhou University in China.  This first draft of the yak genome proved, unsurprisingly, similar to the already-known cattle genome.  Indeed, the average protein similarity between yak and cattle is 99.5%. Genetic analysis of these two genomes suggest that yaks and cattle diverged approximately 4.9 million years ago, which is comparable to the time at which humans and chimps diverged.
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It is, however, the differences rather than the similarities between yaks and cattle which are most illuminating.  The researchers found that three genes related to hypoxia response were selected for in yaks but not in cattle.  Hypoxia is a condition triggered by low oxygen and is a serious concern for cattle living in high-altitude, low-oxygen environments.  One of the yak hypoxia genes (ADAM17) is particularly interesting because certain mutations in the human version of this gene are more common in high-elevation Tibetans than those living at lower elevations.
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In addition to genes involved in hypoxia response, yaks seem especially evolved to deal with nutritional hardships. The researchers found five genes selected for in yaks that help them deal with limited food resources.  These genes help yaks metabolize sugars, fats and proteins as well as regulate the amount of stomach acid produced and perhaps help the yak utilize nitrogen better.
The yak is an adaptive creature, and its genetic differences from cattle help clarify how they manage to live on the harsh, high plateaus. Although more research is needed, the yak and his DNA may eventually provide a window into better understanding high altitude sickness in humans. Now, I’d drink some [yak-butter tea] to that!

Health + Traits — Page 28