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23andMe Blog Team

The Final Episode of Faces of America

<img loading="lazy" decoding="async" class="alignright size-medium wp-image-6064" title="heartrhythm" src="https://blog-api.23andme.com/wp-content/uploads/2010/02/heartrhythm-300x209.jpg" alt="" width="300" height="209" srcset="https://blogcms.23andme.com/wp-content/uploads/2010/02/heartrhythm-300x209.jpg 300w, https://blogcms.23andme.com/wp-content/uploads/2010/02/heartrhythm.jpg 350w" sizes="auto, (max-width: 300px) 100vw, 300px" />
Atrial fibrillation (AF) is the most common irregular heart rhythm, affecting one in four people over the age of 40. While not usually life-threatening on its own, individuals with the condition are at increased risk of stroke and heart failure. AF appears most frequently in older, male individuals with a history of obesity or cardiovascular problems, but some people develop it at a young age and with no obvious heart disease. This type of AF, known as “lone” AF, tends to run in families but is otherwise difficult to diagnose.
<a href="https://blog.23andme.com/articles/snpwatch-genetic-variation-may-increase-risk-of-atrial-fibrillation-and-stroke/">Previous studies</a> covered by The Blog have linked common genetic variants to AF, but these studies have focused mainly on the typical, later-onset type of AF. Led by Patrick Ellinor and Stefan Kaab, a group of researchers from the United States and Europe investigated the genetic basis for lone AF in a group of about 1,300 people of European ancestry with the condition and more than 12,000 people without AF. Their study, published this week in <a href="https://dx.doi.org/10.1038/ng.537">Nature Genetics</a>, connected the genetic variant with increased risk of lone AF.
The variant is located near KCNN3, a gene that codes for an ion channel responsible for controlling the movement of potassium in and out of cells. KCNN3 ion channels in particular are found in “excitable” tissues such as the brain and heart. In mice, abnormalities in the behavior of the KCNN3 gene have been associated with increased blood pressure, but the exact role of KCNN3 in the human heart is unclear. Further research is needed to explore whether KCNN3 may have therapeutic applications for treatment of AF.

Genetic Variant Associated With Lone Atrial Fibrillation

<img loading="lazy" decoding="async" class="alignright size-full wp-image-3461" title="africaglobe" src="https://blog-api.23andme.com/wp-content/uploads/2009/04/africaglobe.jpg" alt="" width="261" height="260" srcset="https://blogcms.23andme.com/wp-content/uploads/2009/04/africaglobe.jpg 347w, https://blogcms.23andme.com/wp-content/uploads/2009/04/africaglobe-150x150.jpg 150w, https://blogcms.23andme.com/wp-content/uploads/2009/04/africaglobe-300x300.jpg 300w, https://blogcms.23andme.com/wp-content/uploads/2009/04/africaglobe-271x271.jpg 271w" sizes="auto, (max-width: 261px) 100vw, 261px" />
The journal Current Biology has a special review issue on the global genetic history of Homo sapiens.   The articles are written for a fairly technical audience, but if it&#8217;s a topic you&#8217;re interested in, you might want to check it out.   All of the articles are available online for free.
<ul>
<li><a href="http://www.cell.com/current-biology/fulltext/S0960-9822%2809%2902071-5" target="_blank" rel="noopener">Archaeogenetics – Towards a ‘New Synthesis’?</a></li>
<li><a href="http://www.cell.com/current-biology/fulltext/S0960-9822%2809%2902065-X" target="_blank" rel="noopener">The Evolution of Human Genetic and Phenotypic Variation in Africa</a></li>
<li><a href="http://www.cell.com/current-biology/fulltext/S0960-9822%2809%2902069-7" target="_blank" rel="noopener">The Archaeogenetics of Europe</a></li>
<li><a href="http://www.cell.com/current-biology/fulltext/S0960-9822%2809%2902068-5" target="_blank" rel="noopener">The Human Genetic History of South Asia</a></li>
<li><a href="http://www.cell.com/current-biology/fulltext/S0960-9822%2809%2902067-3" target="_blank" rel="noopener">The Human Genetic History of East Asia: Weaving a Complex Tapestry</a></li>
<li><a href="http://www.cell.com/current-biology/fulltext/S0960-9822%2809%2902120-4" target="_blank" rel="noopener">The Human Genetic History of Oceania: Near and Remote Views of Dispersal</a></li>
<li><a href="http://www.cell.com/current-biology/fulltext/S0960-9822%2809%2902066-1" target="_blank" rel="noopener">The Human Genetic History of the Americas: The Final Frontier</a></li>
<li><a href="http://www.cell.com/current-biology/fulltext/S0960-9822%2809%2902070-3" target="_blank" rel="noopener">The Genetics of Human Adaptation: Hard Sweeps, Soft Sweeps, and Polygenic Adaptation</a></li>
</ul>

Attention Human Genetic History Buffs

<img loading="lazy" decoding="async" class="alignright wp-image-6020 size-full" title="itpa" src="http://35.88.189.111/wp-content/uploads/2010/02/itpa.jpg" alt="Illustration of ITPA protein structure" width="350" height="238" srcset="https://blogcms.23andme.com/wp-content/uploads/2010/02/itpa.jpg 350w, https://blogcms.23andme.com/wp-content/uploads/2010/02/itpa-300x204.jpg 300w" sizes="auto, (max-width: 350px) 100vw, 350px" />
People chronically infected with the hepatitis C virus currently have only one treatment option. The treatment combines polyethylene glycol (PEG)-related interferon-alpha and ribavirin (RBV).
This drug regimen fails to eradicate the virus in about half of all patients who receive it, but even when it does work. Not only that, but the side effects can be so harmful that treatment has to be scaled back or abandoned altogether.
<h2>New Research</h2>
In up to two-thirds of all hepatitis C patients, RBV treatment leads to the destruction of red blood cells. In addition, it decreases the amount of oxygen that can be transported throughout the body, a condition called hemolytic anemia.
New research, published online yesterday in the journal <a href="https://dx.doi.org/10.1038/nature08825" target="_blank" rel="noopener noreferrer">Nature</a>, shows that genetic variants that cause a usually benign enzyme deficiency actually offer some protection against this condition.
The study was conducted by researchers Jacques Fellay, Alexander Thompson, and Dongliang Ge at Duke, along with colleagues from the Schering-Plough Research Institute and the Johns Hopkins School of Medicine. Together, they studied about 1300 European Americans, 200 African Americans, and 100 Hispanics receiving hepatitis C treatment.
The patients had their hemoglobin (the oxygen-carrying protein in red blood cells) levels measured at the beginning of their treatment. Then, measured again at the four-week mark. This is when many patients must begin treatment to stimulate red blood cell production due to RBV-induced anemia.
The researchers also analyzed the patient&#8217;s DNA. They looked for genetic variants associated with hemoglobin level changes.
<h2>Genetic Variants of Interest</h2>
The researchers found several variants on chromosome 20 had a significant association with maintaining good hemoglobin levels after RBV treatment.   A deeper analysis of this DNA region revealed that the effect could be traced to two variations in the ITPA gene.
The ITPA gene encodes an enzyme that helps break down a substance called inosine triphosphate in cells.
The less common versions of the two variants the researchers identified reduce the ITPA enzyme&#8217;s function.
In most people this isn&#8217;t a problem.   For people taking drugs called thiopurines, which are used to prevent organ rejection in transplant patients and to treat leukemias and autoimmune disease, reduced ITPA activity may lead to<a href="https://www.ncbi.nlm.nih.gov/pubmed/19151640?ordinalpos=1&amp;itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_SingleItemSupl.Pubmed_Discovery_RA&amp;linkpos=5&amp;log$=relatedreviews&amp;logdbfrom=pubmed" target="_blank" rel="noopener noreferrer"> toxicity</a>.   What the new study found is that for people receiving treatment for hepatitis C, less ITPA enzyme function is actually a good thing.
Of the people in the current study predicted to have less than one-third of the normal ITPA activity due to their genetics, none ended up with hemoglobin levels below the level traditionally set as a threshold for RBV dose reduction.   Of those with normal ITPA levels, 11.7% had their hemoglobin levels dip into the danger zone.
<h2>Looking Ahead</h2>
More research into the genetics of RBV-induced anemia will be needed.   The exact effect varied among the different populations studied, the researchers estimate that about 20-30% of the variability in hemoglobin level reduction in response to RBV treatment was explained two variants.   There was no significant association between these SNPs and the efficacy of hepatitis C treatment.
Because having low levels of ITPA enzyme activity do not seem to cause problems for most people.
The authors suggest that drugs that inhibit this enzyme could be developed so that people receiving RBV treatment for hepatitis C could be protected against anemia. Even if they do not carry the protective genetic variations.
Illustration of ITPA protein structure: <a href="https://en.wikipedia.org/wiki/File:Protein_ITPA_PDB_2car.png" target="_blank" rel="noopener noreferrer">Emw</a>

Enzyme Deficiency May Protect Against Serious Hepatitis C Treatment Side Effect

<img loading="lazy" decoding="async" class="alignright size-full wp-image-6003" title="bushmen" src="https://blog-api.23andme.com/wp-content/uploads/2010/02/bushmen.jpg" alt="" width="350" height="232" srcset="https://blogcms.23andme.com/wp-content/uploads/2010/02/bushmen.jpg 350w, https://blogcms.23andme.com/wp-content/uploads/2010/02/bushmen-300x199.jpg 300w" sizes="auto, (max-width: 350px) 100vw, 350px" />Group of hunters from the Ju/’hoansi tribe in the Namibian Bush/ Stephan C. Schuster
Researchers from Penn State University, the University of New South Wales in Australia, and the Baylor College of Medicine have sequenced the genomes of four individuals from different groups of the click-speaking San of southern Africa, as well as of Bishop Desmond Tutu of South Africa.   Their results, published online yesterday in the journal <a href="https://dx.doi.org/10.1038/nature08795" target="_blank" rel="noopener">Nature</a>, are providing striking new insights into human genetic diversity.
Joanna Mountain, 23andMe&#8217;s Senior Director of Research, has been studying the genetics of click-speaking peoples of Africa for over ten years.   Dr. Mountain said the new study &#8220;has demonstrated that any two San individuals are as genetically different from one another as a European and a Chinese individual. Clearly the linguistic diversity of the San is matched or even exceeded by their genetic diversity. Furthermore, even though the San Bushmen are often described, even by this study&#8217;s authors, as the &#8216;oldest known lineage of modern humans,&#8217; the new genetic data reveal that the San have evolved genetically as much as any group, partly through the random mutations that occur over time, but also through changes that enabled them to handle their often challenging, exceedingly dry environment.&#8221;
Read more about this study:
<ul>
<li><a href="https://www.nytimes.com/2010/02/18/science/18genome.html" target="_blank" rel="noopener">New York Times</a></li>
<li>Technology Review</li>
<li>Not Exactly Rocket Science</li>
</ul>

Southern African Genomes Sequenced

<img loading="lazy" decoding="async" class="alignright size-full wp-image-5986" title="iStock_000000081817XSmall" src="https://blog-api.23andme.com/wp-content/uploads/2010/02/iStock_000000081817XSmall.jpg" alt="" width="364" height="273" srcset="https://blogcms.23andme.com/wp-content/uploads/2010/02/iStock_000000081817XSmall.jpg 400w, https://blogcms.23andme.com/wp-content/uploads/2010/02/iStock_000000081817XSmall-300x225.jpg 300w" sizes="auto, (max-width: 364px) 100vw, 364px" />
The candles on your birthday cake tell you how many years you&#8217;ve lived through, but they might not be a reflection of your biological age.
Little bits of DNA called telomeres protect the ends of chromosomes.   Over time, through repeated rounds of cell division, telomeres get shorter and shorter.   Thus, telomere length is a marker of biological aging. Research recently published in the journal <a href="https://dx.doi.org/10.1038/ng.532" target="_blank" rel="noopener noreferrer">Nature Genetics</a> that found a common DNA variation associated with telomere length suggests that some people are genetically programmed to age at a faster rate.
Researchers from the University of Leicester and King&#8217;s College London analyzed the DNA of more than 12,000 Europeans.   They found that each copy of the less common G version of the SNP was associated with about a 75 base pair reduction in average telomere length.   This is equivalent to about 3.6 years of biological aging as measured by telomere length loss.
This finding could have important implications because biological aging isn&#8217;t just a matter of wrinkles and aching joints.   Shorter telomeres have been linked with age-associated conditions such as heart disease and certain types of cancer.   But that&#8217;s not to say that people with variants that predict shorter telomeres should give up on doing all they can to keep young.
&#8220;Genetically susceptible people may age even faster when exposed to proven &#8216;bad&#8217; environments for telomeres like smoking, obesity or lack of exercise–and end up several years biologically older and succumbing to more age-related disease,&#8221; said one of the study&#8217;s senior authors, Tim Spector of King&#8217;s College London, in a<a href="http://www.eurekalert.org/pub_releases/2010-02/uol-sif020410.php" target="_blank" rel="noopener noreferrer"> press release</a>.
<ul>
<li>A previous Blog post about telomeres can be found <a href="https://blog.23andme.com/2008/08/26/snpwatch-too-short-too-fast-%E2%80%93-a-genetic-variation-associated-with-telomere-length/" target="_blank" rel="noopener noreferrer">here</a>.</li>
<li>You may have heard about telomeres in the news recently: The <a href="http://nobelprize.org/nobel_prizes/medicine/laureates/2009/illpres.html" target="_blank" rel="noopener noreferrer">Nobel Prize in Physiology or Medicine 2009 </a>was awarded jointly to Elizabeth Blackburn, Carol Greider and Jack Szostak &#8220;for the discovery of how chromosomes are protected by telomeres and the enzyme telomerase.&#8221;</li>
</ul>

Researchers Identify Variation Associated with Biological Aging

<img loading="lazy" decoding="async" class="alignright size-full wp-image-5968" title="inuk" src="https://blog-api.23andme.com/wp-content/uploads/2010/02/inuk.jpg" alt="" width="350" height="367" srcset="https://blogcms.23andme.com/wp-content/uploads/2010/02/inuk.jpg 350w, https://blogcms.23andme.com/wp-content/uploads/2010/02/inuk-286x300.jpg 286w" sizes="auto, (max-width: 350px) 100vw, 350px" />Artist&#8217;s impression of Inuk based on genetic analysis 
Nuka Godfredsen/Nature
Editor&#8217;s note: This post has been edited from the original to reflect changes in 23andMe&#8217;s product.
Tufts of hair rescued from the permafrost in Greenland and then tucked away in a basement in Denmark for more than 20 years have given scientists their first glimpse into the genetics of an ancient human.
Eske Willerslev and Morten Rasmussen of the Centre for GeoGenetics at the Natural History Museum of Denmark and the University of Copenhagen, along with an international team of collaborators, have sequenced 80% of the genome of a man from the <a href="http://www.natmus.dk/sw18632.asp" target="_blank" rel="noopener">Saqqaq Culture</a> who walked the earth about 4,000 years ago.   By comparing this ancient DNA sequence to what is known about the genetics of modern humans, the researchers were able to piece together a picture of what the man they call Inuk (&#8220;human&#8221; or &#8220;man&#8221; in Greenlandic) likely looked like, where his people came from, and how he&#8217;s related to modern populations.   The results were published online today in the journal <a href="https://dx.doi.org/10.1038/nature08835" target="_blank" rel="noopener">Nature</a>.
Inuk&#8217;s DNA revealed that he had type A+ blood.   He likely had brown eyes and thick, dark hair.   His skin was probably not the light color found in modern day Europeans.   Inuk&#8217;s earwax was dry and he had shovel-graded front teeth, both characteristics common in Asian and Native American populations.   Several of the genetic variants he carried suggest that he had a metabolism and body mass well-suited to cold climates. The researchers even found that Inuk&#8217;s genetics are indicative of an increased risk of baldness.
&#8220;Because we found quite a lot of hair from this guy, we presume he died quite young,&#8221; Willerslev said in a press briefing.
(Although as Harvard professor and <a href="http://improbable.com/2009/01/12/lfhcfs-members-genome-sequenced/" target="_blank" rel="noopener">Luxuriant Flowing Hair Club for Scientists</a> member Steven Pinker found when analysis of his DNA also suggested a propensity for baldness, DNA is not always destiny.)
Analysis of Inuk&#8217;s <a href="https://www.23andme.com/gen101/graphics/ancestry/" target="_blank" rel="noopener">Y chromosome</a> revealed that his paternal haplogroup is Q1a, which is commonly found among Siberian and Native American populations. <a href="https://dx.doi.org/10.1126/science.1159750" target="_blank" rel="noopener">Previous analysis</a> by the same research group had revealed that Inuk&#8217;s maternal haplogroup, determined by his mitochondrial DNA, is D2a1.   This same lineage is commonly found in modern-day Aleuts of the Commander Islands in the Bering Sea and the Siberian Sireniki Yuits (Asian Eskimos).
Since discovery of the remains of the Saqqaq Culture in the 1950s, there has been disagreement over how these people were related to others that crossed the Bering Strait into the New World.   By analyzing Inuk&#8217;s DNA and comparing it to modern populations, the researchers determined that the Saqqaq are most closely related to the <a href="https://en.wikipedia.org/wiki/Nganasan_people" target="_blank" rel="noopener">Nganasans</a>, <a href="https://en.wikipedia.org/wiki/Koryaks" target="_blank" rel="noopener">Koryaks</a> and <a href="https://en.wikipedia.org/wiki/Chukchi_people" target="_blank" rel="noopener">Chukchis</a> of Siberia.   The long-gone Saqqaqs most likely left Siberia for the New World about 5,500 years ago, independently from the ancestors of present-day Native Americans and Inuit.
Now that his team has shown that full genome sequence analysis of ancient samples is feasible, Willerslev expects that there will be an explosion of work in the field.   He says that sequencing of DNA from South American mummies could help illuminate the population history and genetic diversity of Native Americans from before the arrival of Europeans.   Willerslev also suggests that sequencing ancient human DNA could reveal when certain genetic diseases become prevalent in different populations.

Researchers Use SNP Analysis to Paint Picture of an Ancient Human

Faces of America is a four-part series in which Harvard scholar Henry Louis Gates, Jr. uses genealogy and genetics to explore the family histories of 12 renowned Americans in an effort to understand what made the United States the place it is today.
The list of participants includes:
<ul>
<li>Elizabeth Alexander, professor and poet</li>
<li>Mario Batali, chef</li>
<li>Stephen Colbert, comedian</li>
<li>Louise Erdrich, novelist</li>
<li>Malcolm Gladwell, journalist</li>
<li>Eva Longoria, actress</li>
<li>Yo-Yo Ma, musician</li>
<li>Mike Nichols, director</li>
<li>Her Majesty Queen Noor</li>
<li>Dr. Mehmet Oz, television host/heart surgeon</li>
<li>Meryl Streep, actress</li>
<li>Kristi Yamaguchi, figure skater</li>
</ul>
Sneak peaks of each participant&#8217;s unique story are available on the <a href="https://www.pbs.org/wnet/facesofamerica/" target="_blank" rel="noopener">Faces of America</a> page at pbs.org.
All four episodes promise to be very interesting.   If you&#8217;re a fan of 23andMe, be sure to catch the episode featuring genetic ancestry analysis by our scientists on March 3.   Each participant was offered the same <a href="https://www.23andme.com/ancestry/lineage/" target="_blank" rel="noopener">maternal and paternal ancestry</a> and <a href="https://www.23andme.com/ancestry/origins/" target="_blank" rel="noopener">global origins</a> information we give every Complete and Ancestry Edition customer.   And now that <a href="https://www.23andme.com/ancestry/relfinder/" target="_blank" rel="noopener">Relative Finder</a> has had its official launch, these famous Americans can also use their DNA to connect with living cousins from all around the world.
Faces of America with Henry Louis Gates, Jr. premieres nationally Wednesdays, February 10 — March 3, 2010 from 8-9 p.m. ET on PBS.   Check your local listings <a href="https://www.pbs.org/wnet/facesofamerica/schedule/" target="_blank" rel="noopener">here</a>.   The first full-length episode will be available online on Thursday, February 11.

Faces of America on PBS

<img loading="lazy" decoding="async" class="alignright size-full wp-image-4225" title="istock_000008809355xsmall" src="https://blog-api.23andme.com/wp-content/uploads/2009/07/istock_000008809355xsmall.jpg" alt="" width="355" height="262" srcset="https://blogcms.23andme.com/wp-content/uploads/2009/07/istock_000008809355xsmall.jpg 403w, https://blogcms.23andme.com/wp-content/uploads/2009/07/istock_000008809355xsmall-300x222.jpg 300w" sizes="auto, (max-width: 355px) 100vw, 355px" />
There&#8217;s no doubt that blood saves lives.   According to the Red Cross, in the United States alone about five million people need a total of 14 million pints of blood each year.   That&#8217;s <a href="http://www.redcrossblood.org/learn-about-blood/blood-facts-and-statistics" target="_blank" rel="noopener">38,000 pints every day</a>.
But transfusions are not without their dangers.   Among them is transfusion-related acute lung injury (<a href="http://www.nursingcenter.com/prodev/ce_article.asp?tid=771975" target="_blank" rel="noopener">TRALI</a>), a rare but potentially life-threatening condition that happens when there is a clash between donor and recipient blood.   TRALI is one of the major causes of transfusion-association deaths in the developed world.
New research, recently published in the journal <a href="https://dx.doi.org/10.1038/nm.2070" target="_blank" rel="noopener">Nature Medicine</a>, suggests that many cases of TRALI are due to a difference at just one genetic variation between donor and recipient.   This finding could someday enable screening before a transfusion is done, allowing doctors to reduce the risk of TRALI.
One reason TRALI happens is that a donor&#8217;s blood contains antibodies that recognize something in the recipient&#8217;s blood as an enemy.   These donor antibodies mount an attack that sets off a chain reaction of immune responses in the recipient&#8217;s body, leading to lung injury.   Several triggers for this type of TRALI have been identified.   One of these, the HNA-3 antigen, has repeatedly been associated with severe and fatal TRALI reactions.
HNA-3 comes in two versions: HNA-3a and HNA-3b.   A person whose body expresses only the HNA-3a version can make antibodies against the HNA-3b version if he or she is exposed to it somehow.   Likewise, a person whose body expresses only the HNA-3b version of the protein can end up with antibodies against the HNA-3a version. Someone who expresses both HNA-3a and HNA-3b, as a result of inheriting a different version from each parent, won&#8217;t make antibodies against either version.   For reasons that aren&#8217;t really understood, only antibodies against the HNA-3a version are relevant when it comes to TRALI.
The most common route of exposure to foreign versions of the HNA-3 antigen is childbirth.   A woman can be exposed to her child&#8217;s blood, and if it contains a different version of HNA-3 than her body is used to, she might produce antibodies.   The likelihood that a woman will have antibodies against HNA-3 increases with each birth.
The authors of the new study suggest that their new findings can be used to develop a large-scale screening program that could reduce the risk of TRALI.   Blood donors could be genetically screened to find those who are capable of producing antibodies against HNA-3a (i.e., they are AA at ).   Alternatively, the new genetic information could help scientists create artificial HNA-3a antigens that could be used in the lab to screen donated blood directly.

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