<img loading="lazy" decoding="async" class="alignright size-full wp-image-2759" title="heartman" src="https://blog-api.23andme.com/wp-content/uploads/2009/02/heartman.jpg" alt="" width="350" height="260" srcset="https://blogcms.23andme.com/wp-content/uploads/2009/02/heartman.jpg 350w, https://blogcms.23andme.com/wp-content/uploads/2009/02/heartman-300x223.jpg 300w" sizes="auto, (max-width: 350px) 100vw, 350px" />
A common genetic variation may influence how well a person recovers from heart surgery, a study published online yesterday in the <a href="https://dx.doi.org/10.1681/ASN.2008080915" target="_blank" rel="noopener noreferrer">Journal of the American Society of Nephrology</a> suggests.
Coronary artery bypass surgery, which involves using blood vessels from elsewhere in the body to reroute blood around clogged arteries feeding the heart, increases the risk of low blood pressure and shock.   Norepinephrine can be used to bring blood pressure back up to acceptable levels, but a variation in the gene for an enzyme critical to the metabolism of this drug, COMT, may make some people less responsive.
Researchers studied 260 people who had had bypass surgery and found that those who carried an A at both copies of went into shock more often compared to those with other genotypes (69% vs. 57% in AG people and 46.6% in GG people). The A version of produces a less efficient version of the COMT enzyme.
Prolonged shock, lasting more than 48 hours, was also more frequent in people with two As (25% vs. 13% for AG and 6.8% for GG). Because the body responds to shock by restricting blood flow to the kidneys, people with two As at also had greater frequency of acute kidney injury.
The median hospital stay after bypass surgery was longer for people with two As at : nine days vs. eight days for AG and seven days for GG.
More research on the effects of the COMT variation investigated in this study and variations in other genes that could also affect recovery after bypass surgery will be needed.   But if confirmed, the researchers suggest that their findings could help tailor drug regimens and lead to better outcomes.
“If confirmed in larger trials, preoperative COMT genotyping together with known clinical risk factors could aid in preoperative risk stratification to anticipate occurrence of circulatory and renal dysfunction, and prolonged recovery.   Patients thus identified may benefit from an individualized treatment…” the authors conclude.

23andMe Blog

23andMe Blog Team

Genetic Variation May Influence Heart Surgery Recovery

When scientific research is published, the authors often confess that they wish they&#8217;d collected more data. Critical reviews of research studies often say the same thing. Indeed, if there&#8217;s anything scientists love, it&#8217;s more data.<img loading="lazy" decoding="async" src="https://blog-api.23andme.com/wp-content/uploads/2016/08/Africa_icon-300x244.jpg" alt="" class="alignright size-medium wp-image-24241" width="300" height="244" srcset="https://blogcms.23andme.com/wp-content/uploads/2016/08/Africa_icon-300x244.jpg 300w, https://blogcms.23andme.com/wp-content/uploads/2016/08/Africa_icon-768x625.jpg 768w, https://blogcms.23andme.com/wp-content/uploads/2016/08/Africa_icon-1024x834.jpg 1024w, https://blogcms.23andme.com/wp-content/uploads/2016/08/Africa_icon-880x717.jpg 880w, https://blogcms.23andme.com/wp-content/uploads/2016/08/Africa_icon-1180x961.jpg 1180w, https://blogcms.23andme.com/wp-content/uploads/2016/08/Africa_icon.jpg 2014w" sizes="auto, (max-width: 300px) 100vw, 300px" />
Which is why the members of an international team of genetic anthropologists led by Sarah Tishkoff of the University of Pennsylvania are probably quite pleased with themselves. In a new study published this week in <a href="http://www.sciencemag.org/cgi/content/abstract/1172257" target="_blank" rel="noopener noreferrer">Science</a>, the team took the concept of &#8220;more is more&#8221; to heart by collecting and analyzing the DNA of thousands of people, mostly from Africa, so that they might uncover more clues to not only the genetic make-up of modern Africans, but also the genetic history of Africans and non-Africans alike.

<h6>Genetic Diversity</h6>
The scientists&#8217; first step was to collect DNA from a diverse set of Africans. Africa is the most culturally and linguistically diverse place on Earth, so it was important to take a wide sample of individuals from all corners of the continent. In total, they collected 2,432 DNA samples from 113 diverse and distinct groups of people from across the African continent as well as 60 non-African groups. They sampled everyone from the Mozabite Berbers of Morocco to the hunter-gatherer San of the Kalahari Desert, and many in between.
But the hard work didn&#8217;t stop there. The scientists then examined 1,327 genetic markers across the human genome for each individual studied. While many studies focus on a particular part of the genome such the mitochondrial DNA or the Y chromosome, this study took a comprehensive approach. Finally, the researchers used sophisticated statistical techniques, piecing together how these populations from Africa and around the world were the same, and how they were different.
The results confirmed that Africa has the highest genetic diversity of any continent, as many scientists have proposed. In fact, the authors found genetic diversity to decrease the further one traveled away from Africa. Genetic diversity is often used as a measure of how long ago humans inhabited a region – conventional wisdom places the earliest humans in East Africa, which had exceptionally high genetic diversity according to this study, though an analysis by the researchers put the origin of the human expansion farther south near the border of Namibia and Angola.
The study also shed light on the incredible genetic diversity among African populations, said Roy King, a professor of psychiatry and anthropological geneticist from Stanford University:
<blockquote>
Not only did farming and pastoral communities differ from hunter-gatherers, but within the broad range of agricultural populations of West and West-Central Africa – from which many African Americans derive their ancestry – the authors also found some genetic diversity. For example, the Dogon of Mali, although geographically near the Mandinka of Senegal, cluster with North African Berber populations. Thus, this study supports the notion that not only is Africa varied in culture – art, music, religion and language – but also harbors a rich genetic diversity across its multitude of ethnic groups.
</blockquote>
<h6>Languages</h6>
The authors also found a loose connection between the genetics of a population and its language. However, there were a few exceptions, most often the result of a population adopting a new language within the last few thousand years.
The sheer size and diversity of the DNA samples collected allowed the researchers to construct a human family tree based on their analyses. Not unexpectedly, the tree they constructed fits well with current theories on the genetic relationship between Africans and non-Africans; namely that all non-Africans are descended from a particular group or groups of people who were the first humans to migrate out of Africa tens of thousands of years ago.
This study is important for a multitude of reasons. It has been able to confirm theories from the archaeological, cultural, and linguistic records on the origins and movements of Africans and non-Africans.
&#8220;It fits nicely with earlier genetic studies, while subverting the early 20th century colonialist idea of sub-Saharan Africa as constituting a homogeneous genetic an cultural unit,&#8221; King said.
It also creates a new resource that historians, linguists, archaeologists and scientists from a range of other disciplines can use in their own work. If we are lucky, this study will bring forth a flurry of activity surrounding the origins and history of the African continent, and the people who live there.
Credit: istockphoto/Erie

Scientists Publish Largest-Ever Study on the Genetics of Modern Africans

I spent the better part of my undergraduate career lugging around massive biology textbooks.  
General biology, genetics, embryology: It didn&#8217;t matter, they all weighed a ton. I pored over endless chapters of text, highlighting the important sentences, always wishing for more photos, more diagrams, more graphs. A single well-made diagram or image was easier to understand than the preceding 10 paragraphs about the same topic.   I always wished that my textbooks were a little more visual and a little less wordy.   An added benefit, I thought, would be that I could shave a few pounds from my backpack.
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My college days are long over. But my wish may have finally come true, in the form of a new graphic guide to genetics entitled The Stuff of Life: A Graphic Guide to Genetics and DNA, by Mark Schultz.   Published in December, it takes a more visual approach to presenting the most current knowledge on a particular branch of the biological sciences close to my heart: genetics.

The Stuff of Life is centered around a group of aliens who are trying to understand the genetics of all life on earth.  These aliens are both rather ugly (the illustrator has drawn them to resemble sea cucumbers) and rather arrogant.  They can&#8217;t seem to understand why a lowly, hairy primate has come to dominate the planet and make such amazing advances in science and technology. In the style of a comic book, with various windows and balloons leading us from the origins of the earth 4.6 billion years ago to modern day applications of genetics and DNA, it falls flat in oddly juxtaposing complex information and somewhat juvenile humor.
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For anyone who hasn&#8217;t taken a college (or advanced high school level) biology class, the information presented will seem overwhelming at best, and confusing at worst.  For those who are well versed in the biological sciences, the information may be understandable but the humor will seem trite and silly.   After the first few chapters of the cucumberesque aliens repeatedly exclaiming that they can&#8217;t believe humans have managed to understand how genes are passed down from parents to children, that they can&#8217;t believe humans have been able to sequence DNA, understand the genetics of cancer, and create genetically modified organisms, I began to dread their appearances. I stopped reading the sections focused on them, instead skipping to the parts that contained actual information. Once I did I began to enjoy the book much more.
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The organization of the book is similar to a standard introductory genetics textbook.   It begins with a description of the structure of the cell, DNA, and how the genes housed within our DNA can determine thousands of physical traits.   Schultz then moves quickly forward, presenting important genetics concepts such as inheritance, dominant vs. recessive alleles, and why my cat has two different colors of fur.   Finally, he spends the last one-third of the book examining modern-day applications to the study of genetics.
&nbsp;
The strategy works well by allowing the reader to understand the practical value of understanding the basic genetics concepts that were brought up in earlier chapters.   Indeed, having more applications-centric lectures during college might have silenced the students who never understood why this field is so important.   Undoubtedly, this section was written with the more general reader in mind.   It is easily the best section of the entire book.
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Though the constant banter from the sea cucumber-like aliens should not interest anyone over the age of 10, this book would be of use to those currently taking an introductory course in biology, as it might help solidify more difficult concepts that might prove difficult to students.   For educators, this book could prove useful in providing fresh ideas on how to present some of the most important genetics concepts.
&nbsp;
The uneven feeling I got from reading The Stuff of Life is something that must constantly be a fear for anyone who is trying to make science fun and accessible to the general populace.   Presenting such important topics as genetics and DNA that are easy for anyone to understand, scientifically accurate, AND enjoyable, is no easy feat.   And, while The Stuff of Life may have stumbled in some aspects, it is most certainly a noble effort, and may lighten the load in biology majors&#8217; backpacks in the coming months.   I sincerely hope that Schultz continues with more volumes, though I could do without those sea cucumbers next time.

Connections Between Brain Cells May Be Key To Autism Puzzle

Editor&#8217;s note: Some of the tools described in this post no longer reflect the current 23andMe product offerings.
Every family has its legends.
Maybe it&#8217;s a story about how they&#8217;re descended from a passenger on the Mayflower, a Confederate soldier or <a href="http://www.theatlantic.com/doc/200205/olson" target="_blank" rel="noopener noreferrer">Charlemagne</a>.
<div id="attachment_3400" style="width: 279px" class="wp-caption alignright"><img loading="lazy" decoding="async" aria-describedby="caption-attachment-3400" class="wp-image-3400 size-full" src="http://35.88.189.111/wp-content/uploads/2009/04/pocahontas.jpg" alt="" width="269" height="350" srcset="https://blogcms.23andme.com/wp-content/uploads/2009/04/pocahontas.jpg 269w, https://blogcms.23andme.com/wp-content/uploads/2009/04/pocahontas-231x300.jpg 231w" sizes="auto, (max-width: 269px) 100vw, 269px" />Pocahontas.</div>
Of all the classic American family legends, stories of a Native American ancestor are among of the most common. Many times there&#8217;s a well-documented link to a Native forbear: Two First Ladies (Edith Wilson and Nancy Reagan) and one Duchess of Windsor (Wallis Simpson) are proven descendants of Pocahontas.
Other times, the evidence amounts to little more than vague tales about a rugged pioneer and a Cherokee princess. (Learn what&#8217;s wrong with that scenario <a href="http://www.native-languages.org/princess.htm" target="_blank" rel="noopener noreferrer">here.</a>)
Now 23andMe customers who are curious about whether they may have Native American ancestors can look for evidence of it in their genes.
The Native American Ancestry Finder uses some existing 23andMe features – Ancestry Painting, <a href="https://www.23andme.com/you/haplogroup/maternal/" target="_self" rel="noopener noreferrer">Maternal Line</a> and <a href="https://www.23andme.com/you/haplogroup/paternal/" target="_self" rel="noopener noreferrer">Paternal Line</a> – to look for genetic signatures that are likely to have come from a Native American ancestor.

The Maternal Line and Paternal Line elements of the Finder are pretty straightforward; certain mitochondrial DNA (maternal) and Y chromosome (paternal) haplogroups are often found among Native Americans.
These include mitochondrial haplogroups A2, B2, C1, D1 and X2a – which are found exclusively among Native Americans. People in some other branches of the A, B, C and D haplogroups may also have Native American ancestry, but their maternal lines could also trace to Asia. On the paternal side, only Q3 is exclusive to Native Americans, though anyone with a Y chromosome in the C, C3 or Q haplogroup could conceivably have Native American forbears.
<div id="attachment_3392" style="width: 251px" class="wp-caption alignleft"><img loading="lazy" decoding="async" aria-describedby="caption-attachment-3392" class="wp-image-3392 size-full" src="http://35.88.189.111/wp-content/uploads/2009/04/natamwoman.png" alt="" width="241" height="350" srcset="https://blogcms.23andme.com/wp-content/uploads/2009/04/natamwoman.png 241w, https://blogcms.23andme.com/wp-content/uploads/2009/04/natamwoman-207x300.png 207w" sizes="auto, (max-width: 241px) 100vw, 241px" />An example of a Native American&#8217;s ancestry painting.</div>
The part of the Finder that uses Ancestry Painting to find evidence for Native American forbears is a little more complicated. It relies on the fact that people of full Native American descent have Ancestry Paintings that are consistently about 75% orange (Asian) and 25% blue (European).
This is due to the fact that Native Americans are ultimately descended from populations that lived in northern and central Asia about 15,000 to 20,000 years ago, and the fact that those regions are intermediate between the reference populations that Ancestry Painting classifies as fully Asian (Japanese and Chinese) and fully European (European-Americans living in Utah).
Then the Finder compares your Ancestry Painting proportions to a table that contains the results of an extensive series of simulations that we performed to determine what would happen to that three-to-one Asian/European proportion over the generations if a Native American and a partner of all-European descent had a child who then reproduced with another all-European partner, and so on. We did the same analysis for a Native American marrying into an all-Asian pedigree.
Unfortunately, partly due to inadequate sampling of Africa&#8217;s genetic diversity, this method cannot yet establish Native American ancestry for African Americans.
We found that it takes at least five generations after the appearance of a single Native American in an otherwise all- European pedigree for the percentage of Asian (orange) DNA to reach zero. In an otherwise all-Asian pedigree that process is much faster – in two generations, the grandchild of that single Native American can have no trace of European in his or her Ancestry Painting.
There are, of course, plenty of Eurasian populations that also have blue-and-orange Ancestry Paintings. So the Native American Ancestry Finder performs a second analysis that can distinguish people of South Asian, Central Asian, Middle Eastern and Ashkenazi descent from those with Native American ancestry.
Unfortunately, there is still some uncertainty when it comes to distinguishing people with Native American ancestry.
It&#8217;s still a work in progress – that&#8217;s what Labs are all about. But we hope customers will help us by trying out the Native American Ancestry Finder and letting us know if anything doesn&#8217;t mesh with what they know about their genealogy.
You can also contribute by taking the &#8220;<a href="https://www.23andme.com/you/23andwe/surveys/" target="_self" rel="noopener noreferrer">Where Are You From?</a>&#8221; survey in <a href="https://www.23andme.com/you/23andwe/surveys/" target="_self" rel="noopener noreferrer">23andWe</a>.

New 23andMe Lab Searches Genome for Native American Ancestry

<img loading="lazy" decoding="async" class="alignright size-full wp-image-3410" title="istock_000002436798xsmall" src="https://blog-api.23andme.com/wp-content/uploads/2009/04/istock_000002436798xsmall.jpg" alt="" width="374" height="248" srcset="https://blogcms.23andme.com/wp-content/uploads/2009/04/istock_000002436798xsmall.jpg 425w, https://blogcms.23andme.com/wp-content/uploads/2009/04/istock_000002436798xsmall-300x199.jpg 300w" sizes="auto, (max-width: 374px) 100vw, 374px" />
DNA Day was created in 2003 by a congressional resolution to celebrate two important milestones in the study of genetics: the 50th anniversary of the description of the double-helix structure of DNA by James D. Watson and Francis H.C. Crick and the completion of the Human Genome Project. DNA Day is usually celebrated on April 25th, but to accommodate classroom schedules, many activities will be taking place a day early on Friday April 24th.
<ul>
<li>DNA Day Chatroom: The National Human Genome Research Institute (NHGRI) will be hosting its annual <a href="https://www.genome.gov/20519689" target="_blank" rel="noopener noreferrer">DNA Day chatroom</a> from 8 a.m. to 6 p.m., EDT on April 24th. Genomics and genetics experts will answer questions from students, teachers and the general public on topics ranging from basic genomic research to the genetic basis of disease to ethical questions about genetic privacy. Transcripts from past chatrooms can be found <a href="https://www.genome.gov/20519689" target="_blank" rel="noopener noreferrer">here</a>.</li>
<li>Teaching Tools for DNA Day: To plan your own DNA Day activities, check out the NHGRI’s collection of <a href="https://www.genome.gov/20519692" target="_blank" rel="noopener noreferrer">teaching tools</a> and webcasts. &nbsp; And don&#8217;t miss our collection of DNA-themed activities.</li>
<li>DNA Day Online: National DNA Day is on Facebook and Twitter. &nbsp; You can compete to win a NHGRI mug in their DNA model photo contest. &nbsp; Pictures can be uploaded through April 24th. &nbsp; You can also send a virtual gene via Facebook (thanks to <a href="https://blog.23andme.com/2008/05/02/giving-the-gift-of-a-virtual-gene/" target="_blank" rel="noopener noreferrer">Genome Alberta</a>) or send a DNA Day e-card.</li>
</ul>
What are you doing to celebrate? &nbsp; Leave us a comment — we’d love to know. &nbsp; And if you know of any cool DNA Day happenings, let us know about those too!

DNA Day 2009 — It’s Almost Here!

<img loading="lazy" decoding="async" class="alignright size-full wp-image-2057" title="DNA Strand" src="https://blog-api.23andme.com/wp-content/uploads/2008/11/istock_000000628100xsmall.jpg" alt="" width="355" height="266" srcset="https://blogcms.23andme.com/wp-content/uploads/2008/11/istock_000000628100xsmall.jpg 400w, https://blogcms.23andme.com/wp-content/uploads/2008/11/istock_000000628100xsmall-300x225.jpg 300w" sizes="auto, (max-width: 355px) 100vw, 355px" />
In 2005 two well-known human geneticists, Francis Collins and Thomas Gelehrter, made a bet: Collins <a href="http://www.gnxp.com/blog/2006/08/collinss-wager.php" target="_blank" rel="noopener">wagered</a> that by the 2008 American Society for Human Genetics meeting, genomewide association studies would have led to the discovery of at least four “validated &#8211; not just guessed at” susceptibility variants for at least five common diseases.
Collins won his bet (and hopefully his beer) — by a margin of more than 200 variants.   According to the <a href="http://www.hugenavigator.net/HuGENavigator/startPageWatch.do" target="_blank" rel="noopener">Human Genome Epidemiology Network</a>, there have been 328 genomewide association studies published to date, and there is no sign of a slow down. This type of research has clearly been successful. But how useful are the variants they identify?
There are two directions from which to consider this question. One is to ask whether the common variants found in genomewide association studies add to science’s understanding of the biology of various common diseases, as well as medicine&#8217;s ability to treat them.   The other is to ask whether the results of genomewide association studies have made it possible to predict individual genetic risk for various diseases.   Three opinion pieces, each with a different perspective, address these questions in the New England Journal of Medicine this week.
<a href="http://content.nejm.org/cgi/content/full/NEJMp0806284" target="_blank" rel="noopener">David Goldstein</a>, director of the Center for Human Genome Variation at Duke’s Institute for Genome Sciences and Policy, doesn’t doubt the veracity of variants found in genomewide association studies.   But he does think that it’s time for geneticists to take a new approach.
“I believe attention should shift from genome scans of ever larger samples to studies of rarer variants of larger effect,” he writes in his NEJM commentary.
Goldstein says continued use of genomewide association approaches that look for common variants associated with common diseases and traits will ultimately lead to an unwieldy number of variants, each with vanishingly small effect sizes. For example, after making some assumptions he calculates that approximately 93,000 common variants could be needed to explain 80% of the population variation in height.
But variants with small effects can be biologically informative, argues <a href="http://content.nejm.org/cgi/content/full/NEJMp0808934" target="_blank" rel="noopener">Joel Hirschhorn</a>, a Harvard genetics professor, in the second NEJM Perspective.   For example, genomewide association studies have identified variants associated with type 2 diabetes, high cholesterol and low bone density that are located in genes targeted by drugs already approved by the FDA for the treatment of these conditions.
“Each of the associated variants at a drug-target locus explains less than 1% of phenotypic variation in the population, demonstrating that small effect sizes do not preclude biologic importance,” he writes.
The discovery of variants with small effect sizes can also point scientists in the direction of new avenues for drug research, says Hirschhorn.   Genomewide association studies of age-related macular degeneration and Crohn’s disease have both revealed new mechanisms of disease that are now being pursued as therapeutic targets.
In the final NEJM Perspective, <a href="http://content.nejm.org/cgi/content/full/NEJMp0810107" target="_blank" rel="noopener">Peter Kraft and David Hunter</a> from the Harvard School of Public Heath address genomewide association studies from the point of view of risk prediction.   They argue that while reliable risk predictions may be possible someday, testing for susceptibility based on common variants is currently premature for most conditions.   Like Goldstein, they note the small effect sizes associated with many of the common variants found so far.
“These factors suggest that many, rather than few, variant risk alleles are responsible for the majority of the inherited risk of each common disease….Estimates of risk based on established locus associations are therefore likely to change substantially in the next few years [as more variants are found],” Kraft and Hunter write.
Hirschhorn has a more optimistic view of the value of the variants identified through genomewide association studies.   He maintains throughout his article that the point of doing these studies is not risk prediction, but does say that it is likely that for some diseases, useful predictive information will emerge.   In fact, for some diseases the variants found to-date already give as much information to clinicians as other routinely used measures.
“For several diseases, associated variants already explain 10 to 20% or more of heritability, a magnitude that is similar to the proportion of risk explained by nongenetic tests in widespread clinical use (such as levels of low-density lipoprotein cholesterol or prostate-specific antigen),” Hirschhorn writes.
Hirschhorn goes on to argue that it is not how of much a disease’s genetics a variant or collection of variants explains, but how this information can shift the cost-benefit ratio of available clinical interventions.
“For diseases without potential therapies, even perfect prediction might not be clinically useful.   By contrast, for diseases with effective preventive measures that are too costly or for which the risk-benefit balance is nearly neutral, small increments in predictive power could help effectively target preventive efforts, with substantial clinical impact,” he writes.
Looking back at that 2005 bet between Collins and Gelehrter, it’s clear that not even the biggest names in the field could imagine just how far human genetics would come in such a short amount of time.   There’s no disputing that the study of common DNA variants has pushed science forward. And as new technologies and methods are developed, we&#8217;re sure to see even more progress.   We here at 23andMe hope to be a part of some of those new discoveries.

328 Genomewide Association Studies and Counting … What Now?

<img loading="lazy" decoding="async" class="alignright size-full wp-image-3370" title="alzheimers" src="https://blog-api.23andme.com/wp-content/uploads/2009/04/alzheimers.jpg" alt="" width="341" height="243" srcset="https://blogcms.23andme.com/wp-content/uploads/2009/04/alzheimers.jpg 435w, https://blogcms.23andme.com/wp-content/uploads/2009/04/alzheimers-300x214.jpg 300w" sizes="auto, (max-width: 341px) 100vw, 341px" />
Researchers have identified a genetic variation that may raise the risk for stroke by affecting brain cells’ ability to respond to injury.
Stroke is the third leading cause of death in the United States, striking <a href="http://www.strokeassociation.org/STROKEORG/AboutStroke/Impact-of-Stroke_UCM_310728_Article.jsp" target="_blank" rel="noopener">almost 800,000</a> people each year. High blood pressure, high cholesterol, smoking, diabetes, obesity and a history of cardiovascular disease can all increase the risk of having a stroke, but studies of families and twins indicate that genes play a substantial role too.   So far, however, the genes underlying stroke risk in the general population remain undetermined.
Scientists combined data from several large studies comprising almost 29,000 people from the United States and the Netherlands to look for genetic variations associated with stroke risk. Their results, published online today in the <a href="http://content.nejm.org/cgi/content/full/NEJMoa0900094" target="_blank" rel="noopener">New England Journal of Medicine</a>, link a region of the genome not previously associated with stroke to increased risk in both black and white populations.
Strokes can be either hemorrhagic (caused by a broken blood vessel that bleeds into or around the brain) or ischemic (caused by a blood clot that blocks blood flow to the brain). Most strokes are the ischemic type.
Combined analysis of data from Caucasian study participants from the United States and the Netherlands revealed that the A version of this SNP is associated with a 1.29 times increased risk of ischemic stroke.   The SNP was also associated with an increased risk for ischemic stroke in a large African American study group — 1.42 times for each copy of an A.   Analysis of a smaller group of African Americans failed to yield a significant association between and stroke.
The risk of stroke is almost doubled for African Americans compared to white Americans, and African Americans are more likely to die from stroke or complications from stroke than any other ethnic group. This SNP is located near the NINJ2 gene, which encodes a protein that has been implicated in nerve cell injury response in animal studies.   Several other SNPs in and around the NINJ2 gene showed modest association with stroke. The authors of the study suggest that SNPs affecting how much protein is made from the NINJ2 gene might influence the brain&#8217;s response when deprived of oxygen by a blood clot.

Genetic Variation May Increase Risk Of Stroke

<img loading="lazy" decoding="async" class="alignright size-full wp-image-3359" title="neanderthaler_278" src="https://blog-api.23andme.com/wp-content/uploads/2009/04/neanderthaler_278.jpg" alt="" width="278" height="206">
Over the past decade, there has been no shortage of studies focused on the relationship between Neanderthals and our own species, Homo sapiens. Researchers have dug deep into the fossil record and our genomes to uncover how closely related we are to the Neanderthals, whether we interacted with them, and even whether our two species shared offspring.
But what about the Neanderthals themselves? We know that beginning around 400,000 years ago, they occupied over 3 million square miles of Europe and Western Asia, from Spain to Iraq. &nbsp; We know that they developed a unique tool technology and that they buried their dead. &nbsp; But what we really don&#8217;t know is how they compared to each other: &nbsp; were there in fact distinct Neanderthal sub-groups, shaped by the vastly different environments in which they lived? &nbsp; Or can they all be considered a single, genetically similar population? These questions are addressed in the most recent issue of <a href="http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0005151" target="_blank" rel="noopener">PLoS One</a> by anthropologists from the UniversitÃ© de la MÃ©diterranÃ©e in France, using a method that is both unique and comprehensive. 
 
This study is of interest not only because it attempts to understand Neanderthal diversity, but also because it utilized data from a various sources. &nbsp; First, the researchers collected data from the mitochondrial DNA sequences of 12 separate Neanderthal skeletons. These skeletons ranged in age from 29,000 to 100,000 years and were uncovered in various parts of the Neanderthal homeland, from Siberia to Spain. &nbsp; The researchers then took physical measurements of the skeletons themselves. Finally, they developed and ran complex computer simulations based on the genetic and skeletal data, in an attempt to discover the most likely scenario for how Neanderthals evolved and spread across much of Eurasia.
The authors concluded that the most likely scenario for how the Neanderthals populated Europe and Western Asia involves three Neanderthal sub-groups: one centered in Western Europe, another in Southern Europe, and the final group in the Levant/Western Asia. &nbsp; They propose that the Neanderthals within each of these sub-groups were more genetically – and perhaps physically – similar to each other than they were to members of another sub-group. &nbsp; This is contrary to the idea that the Neanderthals were a single, uniform population.
This result begs the question of cultural distinctions between the sub-groups. &nbsp; After all, if they were genetically and physically different from one another, it is entirely plausible that cultural differences, such as tool technologies, between the sub-groups also existed. &nbsp; The authors hope to understand cultural differences between Neanderthal sub-groups in the same way as they&#8217;ve understood genetic and physical differences. &nbsp; And, as more fossils are found and more DNA extracted, we will hopefully develop – with even more confidence – a clear picture on the origins and movements of Neanderthals.

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