<img decoding="async" class="right alignright" src="https://blog-api.23andme.com/wp-content/uploads/2008/03/beringstrait.png" alt="beringstrait.png" />Just when you thought everything was starting to make sense — new genetic research on the peopling of the Americas throws us a curve.
There has been plenty of research in both <a href="https://blog.23andme.com/2008/03/07/the-amazing-journey-a-new-synthesis-for-the-peopling-of-america/">genetics</a> and <a href="https://blog.23andme.com/2008/05/09/its-all-about-the-seaweed-new-theories-on-the-peopling-of-the-americas/">archaeology</a> recently trying to figure out how the New World was colonized.
Was it by boat or via the frozen wasteland of the Bering Strait? Was it a fast trip down to South America, or did these first inhabitants take a more leisurely stroll? And when did all this happen anyway? 
<h6>New Evidence</h6>
As each new study is published we are learning vital information on the peopling of the Americas. Ideas and theories continue to be retooled as new evidence comes to light.
This will certainly be the case with regards to a paper in the May 2008 issue of <a href="http://www.plosgenetics.org">PLoS Genetics</a>. In this article, researchers from Oxford and Cornell Universities report on a new computer model they have developed to trace prehistoric human migrations across the globe.
Using genetic information from various populations alive today, the authors estimated how those groups may be related to one another. Then they used those relationships to piece together the prehistoric movements of early humans.
<h6>The First Americans</h6>
As expected, their analysis showed a single migration out of Africa that eventually populated Eurasia and the Americas. However, the results for the Peopling of the Americas were more surprising.
The conventional wisdom states that the first inhabitants of the Americas came from Asia in a single wave more than 10,000 years ago. But when the authors compared the genetic data of two Native American groups (one in Colombia and one in the American Southwest) to groups in East Asia, what they found supported a two-wave migration. 
 The Colombian sample of Native Americans was actually more closely related to the East Asian sample than it was to the American Southwest sample. That suggests the two populations come from independent sources — and that there were at least two separate migrations of humans into the New World. Clearly, one of these migrations would have come from East Asia and made its way into South America. However, the data suggest a separate migration, probably from a different part of Asia or Siberia, came at a different time, and this time only made it to North America. This conclusion is significant, as it contradicts current theories on the topic, which argue a more constant flow of migrants from an original source somewhere in Asia. There are still plenty of questions regarding this research, especially with regard to how it compares to the archaeological record and to previous genetic studies. The answers to these questions can only come with additional research, which, thankfully, is always forthcoming on the peopling of the Americas.

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Peopling of the Americas (Times Two)

<div style="width: 410px" class="wp-caption alignright"><img loading="lazy" decoding="async" src="https://blog-api.23andme.com/wp-content/uploads/2008/05/bushsignsgina.jpg" alt="bushsignsgina.jpg" class="right" width="400" height="254" />White House photo by Eric Draper</div>
President Bush has <a href="https://www.reuters.com/article/politicsNews/idUSN2143439320080521">signed</a> GINA, the Genetic Information Nondiscrimination Act, into law.
The legislation, which passed Congress last month after languishing for more than a decade, will make it illegal for employers or health insurers to discriminate on the basis of genetics. Genetic information will still be fair game in life insurance or long-term care coverage, however.
“This is a tremendous victory for every American not born with perfect genes — which means it’s a victory for every single one us,” said Rep. Louise Slaughter , a New York Democrat who first introduced the bill in 1995.
The law will not go into effect immediately. The insurance provisions take effect in about a year, and the employment rules about six months after that. So it remains to be seen how much of an effect GINA will have, especially when you consider that most states already have laws in place prohibiting genetic discrimination.

It’s Official: Bush signs GINA

<img decoding="async" src="https://blog-api.23andme.com/wp-content/uploads/2008/05/stomach.jpg" alt="stomach.jpg" class="right alignright" />A new study in <a href="https://www.nature.com/ng/index.html">Nature Genetics</a> shows that a version of a SNP in a gene called PSCA is associated with an increased risk in Asians for diffuse-type gastric cancer, a type of stomach cancer.
Gastric cancer, which falls into two main categories — intestinal and diffuse — is the fourth most common type of cancer and second leading cause of cancer death worldwide.
The intestinal type of gastric cancer is typically associated with infection by a type of bacteria called H. pylori, while the diffuse type is not. Previous research suggests that the two types of gastric cancer develop through different pathways and that genetic background is more important for the diffuse type.
<h6>Millennium Genome Project</h6>
The Study Group of Millennium Genome Project for Cancer initially examined more than 85,000 SNPs in 188 diffuse-type gastric cancer patients and 752 healthy controls from Japan to find DNA variations that might be associated with diffuse-type gastric cancer. That research produced a list of 2,880 candidate SNPs that were then examined in an additional 749 patients and 750 controls.
The SNP from that shorter list that was most strongly associated with diffuse-type gastric cancer was rs2976392, in the PSCA gene.
Because the SNPs that are found in genome-wide association studies are often only markers for other SNPs that are actually affecting susceptibility to a disease, the researchers looked at the PSCA gene more closely to find additional SNPs.
PSCA SNP rs2294008 was found to be significantly associated with diffuse-type gastric cancer. Each copy of the T version (which is the most common version in the Japanese population) increased the odds of diffuse-type gastric cancer by 1.67 times.
<h6>Association in Koreans</h6>
The researchers found that rs2294008 was also associated with diffuse-type gastric cancer in a Korean sample of 454 patients and 390 controls. In this population the T version increased the odds of diffuse-type gastric cancer by 1.91 times. In the Korean population, the T version is less common than the C version of SNP rs2294008. 
The researchers think the different versions of rs2294008 might influence the risk for diffuse-type gastric cancer because theory predicts the T and C versions of this SNP should produce slightly different proteins. Laboratory experiments also suggested that when the PSCA gene has the T version of rs2294008, less protein is made from the gene.
More research will be needed to confirm that the T version of rs2294008 is a risk factor for diffuse-type gastric cancer in Asian populations and if so, how it works. Researchers will also need to determine whether this SNP is associated with diffuse-type gastric cancer in other populations.

Associations in Asians for type of stomach cancer

<img loading="lazy" decoding="async" class="alignright size-medium wp-image-231" src="http://35.88.189.111/wp-content/uploads/2008/05/istock_000005569535xsmall-300x225.jpg" alt="" width="300" height="225" srcset="https://blogcms.23andme.com/wp-content/uploads/2008/05/istock_000005569535xsmall-300x225.jpg 300w, https://blogcms.23andme.com/wp-content/uploads/2008/05/istock_000005569535xsmall.jpg 400w" sizes="auto, (max-width: 300px) 100vw, 300px" />One of the most exciting aspects of archaeology is how new research can alter previously held notions about prehistoric events.
One of the most hotly debated events is the peopling of the Americas. Theories on the timing and specifics of the arrival of the first Americans are continuously modified as new evidence from fossil, paleoclimatic, and genetic records is examined.
<h2>First to the New World</h2>
A study in last month’s <a href="https://blog.23andme.com/2008/03/07/the-amazing-journey-a-new-synthesis-for-the-peopling-of-america/">American Journal of Human Genetics</a> argued for an ancient and fast migration of prehistoric humans across the Bering Strait and down the Pacific Coast based on a genetic analysis of present-day Native Americans. That study was provocative because it significantly pushed back the arrival date of humans to the New World to 18,000 years ago from the previous estimate of 13,000 years.
Now, results from a new study in this week’s Science further bolster that theory, using the prevalence of preserved seaweed as an indicator.
Anthropologists at Vanderbilt University excavated a South American archaeological site, Monte Verde II. In southern Chile, Monte Verde II is midway between the Pacific Coast and the Andes mountains. It dates to approximately 14,600 years ago, making it one of the oldest archaeological sites in the New World. The age of Monte Verde II, combined with its extreme southern location, lends additional support to the hypothesis of an early arrival of humans into South America.
<h2>Seaweed</h2>
The sheer abundance of preserved seaweed in various huts at Monte Verde II lends additional support for the initial migration occurring down the Pacific Coast rather than further inland. Seaweed is an incredibly fragile material and does not preserve well. However, remains of seaweed are found all over Monte Verde II. The authors think the seaweed was probably used extensively for food and medicinal purposes, which still continues in present-day coastal communities.
The presence of some foods from inland areas indicates that the inhabitants of Monte Verde also traveled inland at some point during the year or else mingled with other communities that did so.
So, how do these findings help us to understand the earliest inhabitants of the Americas? Most importantly, this study supports the idea that the first Americans traveled down the length of the Americas via the Pacific Coast. However, it also shows that there seems to be some relationship between coastal communities, such as Monte Verde, and those more inland groups.
In fact, the authors of this study use this possible relationship to propose a slight variation on the theme of a coastal migration route, saying that the first inhabitants may have taken a slower journey down the coast, spreading out in the interior along the way. Although this hypothesis needs additional support, it is clear that the debate on the people of the Americas is far from over.

It’s All About the Seaweed: New Theories on the Peopling of the Americas

Editor&#8217;s Note: This post does not reflect our current product offering. 23andMe&#8217;s ancestry product looks at the autosomes (chromosomes 1-22), the sex chromosomes (XY), and mitochondrial DNA (mtDNA). For more information about how results are different for men and women go here.
One of the most exciting parts of 23andMe’s <img decoding="async" class="right alignright" src="https://blog-api.23andme.com/wp-content/uploads/2008/05/gus.jpg" alt="gus.jpg">
<h6>Paternal vs. Maternal</h6>
At present, 23andMe customers can trace two branches of their genetic family tree — one that follows the all-female line on the maternal side (through mitochondrial DNA) and another the all-male line on the paternal side (through the Y chromosome).
Not all DNA is created equal, however: males have both mitochondrial DNA AND a Y chromosome, so they can trace both their maternal and paternal ancestry. Females, who have mitochondrial DNA but no Y chromosome, can trace only their maternal ancestry.
So how can females discover their paternal history? One solution is to ‘borrow’ the Y chromosome of her most immediate paternal ancestor — her father. A female can have her father send his own DNA sample to 23andMe, then examine his Y chromosome as a way of understanding his paternal ancestry and her own.
<h6>Discovering Paternal Ancestry</h6>
But what if a woman&#8217;s father can&#8217;t or won&#8217;t share his DNA? By sharing 23andMe accounts with the right male relative, a woman can still discover both her maternal and paternal ancestry.
So whose DNA can a female customer use, besides her father&#8217;s? It could be anyone who shares his Y chromosome — her brother, paternal uncle (father’s brother), or even paternal grandfather (father’s father). The chart below illustrates some of the possibilities in one woman&#8217;s family tree; male relatives who share her father&#8217;s Y chromosome are depicted in blue.
You may look at the chart and ask: Why not her son’s Y? After all, he&#8217;s a male relative, too. But even though a mother shares 50% of her genes with each of her children, only fathers pass Y chromosomes to their sons. So any examination of her son’s Y chromosome would yield not her father&#8217;s paternal history, but her husband&#8217;s.
<img decoding="async" src="https://blog-api.23andme.com/wp-content/uploads/2008/05/erinpaternal33.png" alt="erinpaternal33.png"> 
The woman whose family tree is shown here (&#8220;Me&#8221;) could determine her paternal ancestry using the Y chromosomes of males who are colored blue.

Whose Y to Use? Paternal Ancestry for Ladies

<img decoding="async" class="right alignright" src="https://blog-api.23andme.com/wp-content/uploads/2008/05/feetscale.jpg" alt="feetscale.jpg" />The Atkins diet, the South Beach diet, the Grapefruit diet, the Cabbage Soup diet — we know all these fad diets have their limits, because ultimately, the only way to lose weight is to eat fewer calories and burn more.
But have you ever thought about what controls your appetite? What if your body didn’t tell you to stop eating when you’d consumed enough calories?
You&#8217;d gain weight, that&#8217;s what. It&#8217;s long been known that mutations in a gene called MC4R cause mice to become bigger and fatter than their regular counterparts.
It&#8217;s thought that eating a lot causes the body to turn on MC4R, which in turn tells the mice to stop eating by making them feel full. There are also rare variations that disrupt the human MC4R protein and cause children to eat too much, leading to severe childhood obesity.
Interesting, you say, but does this apply to the general population too? Research published online Sunday in the journal <a href="https://www.nature.com/ng/index.html" target="_blank" rel="noopener noreferrer">Nature Genetics</a> suggests that the answer is yes.

A large study of over 77,000 Europeans by <a href="https://www.nature.com/ng/journal/vaop/ncurrent/abs/ng.140.html" target="_blank" rel="noopener noreferrer">Loos et al.</a> found a SNP near the MC4R gene, rs17782313, that was strongly associated with body mass index (BMI), a measure of obesity. (To calculate your own BMI, go to: http://www.nhlbisupport.com/bmi/bmicalc.htm) They found that each copy of the C version of rs17782313 was associated with an increase of 0.22 BMI units in adults (for a person of my height, 5 ft 3 in, that’s a little over a pound). In children, they found that this SNP had an even larger effect. Unlike the rare changes in MC4R that cause severe childhood obesity, 30 to 50% of the population has at least one copy of the C allele of rs17782313.
A second paper by <a href="https://www.nature.com/ng/journal/vaop/ncurrent/abs/ng.156.html" target="_blank" rel="noopener noreferrer">Chambers et al.</a>, also published online Sunday in Nature Genetics, studied more than 14,000 Indian Asians and Europeans and found that a different SNP near MC4R, rs12970134, is associated with waist circumference. Each copy of the A version is associated with a 0.88 cm (0.3 in) increase in waist circumference. That means that on average, the waists of people with two copies of the A version of rs12970134 are 0.6 inches larger than the waists of people with two copies of the other version of the SNP. Talk about pinching an inch!
Fortunately for most of us, genes are only one player in our risk for obesity, as our behavior and environment can still play a large role in maintaining a healthy weight.
Calculating your BMI: You can calculate your own BMI using the following formula: multiply your weight in pounds by 0.454 to get your weight in kilograms. Then multiply your height in inches by .0254 to get your height in meters and square the result. Divide your weight in kilograms by your height in meters squared to get your BMI. A BMI less than 18.5 is considered underweight, between 18.5 and 24.9 normal, between 25 and 29.9 overweight, and above 30, obese.

MC4R Gene Associated with Body Mass

<img decoding="async" class="left alignright" src="https://blog-api.23andme.com/wp-content/uploads/2008/05/illuminachip.png" alt="illuminachip.png" />Sometimes our customers ask us about the accuracy of their 23andMe data. How certain are we that they really do have the genotypes we report?
The answer is, very certain. We typically claim that the genotyping technology we use reports the correct call for more than 99.9 percent of the approximately 580,000 single-letter DNA variations we report. Those variations, known as single-nucleotide polymorphisms, or SNPs, are the raw data upon which the 23andMe Personal Genome Service is built.
<h6>Testing Accuracy</h6>
But apparently one of our customers decided to do more than ask. He designed a simple experiment to test the reproducibility of the SNP chips that 23andMe and other companies use to give people access to their genetic data.
Antonio C.B. Oliveira signed himself up for 23andMe and a similar service, then wrote a computer program to compare the genotype calls at the 560,299 SNPs where both companies reported data. He found a grand total of 23 discrepancies, or about 0.004% of the common reported SNPs.
&#8220;This error rate seems to me to be quite acceptable,&#8221; Oliveira concluded on <a href="http://longavista.blogspot.com/">Longa Vista</a>, a blog he established to share his results.
<h6>Another Comparison</h6>
Oliveira is actually the second customer to conduct such an experiment. When Ann Turner compared two datasets for the same person (not herself) back in January, she discovered 35 discrepancies.
And when <a href="http://biology.plosjournals.org/perlserv/?request=get-document&#038;doi=10.1371/journal.pbio.0050254&#038;ct=1">Craig Venter</a> and his colleagues published his full genome last October, they also found the discrepancies between their own sequencing results and two different SNP genotyping platforms to be negligible.
We aren&#8217;t surprised — these results confirm experiments that 23andMe performed before launching our Personal Genomics Service last year. But now 23andMe can say with confidence that independent testing has shown that the Illumina genotyping technology we use is extremely robust.

23andMe Genotyping Technology Aces Independent Tests

<img loading="lazy" decoding="async" src="https://blog-api.23andme.com/wp-content/uploads/2008/05/istock_000002904128xsmall.jpg" alt="istock_000002904128xsmall.jpg" class="right alignright" width="278" height="187" />The amount of sugar in the bloodstream must be tightly controlled. Too much can cause damage to nerves, blood vessels and organs. But too little sugar starves the body, especially the brain, of the energy it needs.
Fasting plasma glucose (FPG) levels are a measure of how well a person’s body can control blood sugar levels, a process that goes awry in diabetes. A report published online today in Science Express finds that FPG levels can be impacted by single-letter variations in genes known to be involved in blood sugar regulation.

<h6>Blood Sugar Levels</h6>
Physicians routinely test their patients&#8217; FPG levels to screen for diabetes and pre-diabetes. A high blood concentration of glucose after 8 to 10 hours of fasting indicates that a person’s ability to regulate blood sugar is impaired. High FPG levels are also associated with coronary heart disease mortality for both diabetic and non-diabetic individuals.
In order to identify genetic variants involved in blood sugar control, Nabila Bouatia-Naji and colleagues carried out a genome-wide association study to find single-nucleotide polymorphisms, or SNPs, correlated with FPG levels.
The most strongly associated SNP in an initial sample of about 650 non-obese French people. The same SNP was correlated with FPG levels in a second sample that included about 3,400 French people, approximately 5,000 Finns and a group of about 860 obese French children.
<h6>Additional Variants</h6>
Two other SNPs that were previously found to be associated with FPG were also found to be significantly associated with FPG levels in this study. The researchers believe that these genes affected by these SNPs affect the threshold level of glucose in the bloodstream, which triggers the secretion of insulin by the pancreas. The higher the threshold, the higher the blood glucose level will rise before insulin starts to regulate it.
“These sequences explain about 5 percent of the normal variation in blood glucose levels between otherwise healthy people,” explained Robert Sladek, one of the study&#8217;s senior authors.
When all three SNPs were considered together to create a score (each person has two copies of each SNP and gets one point for each “low FPG” version, meaning the score can range from 0 to 6), the researchers found that on average people who scored a 5 or 6 had FGP levels 0.24 mmol/l lower than people who scored 0 or 1.
“It’s important to know that a high blood glucose level, even within the normal and non-diabetic range, is a risk factor for early mortality,” said Dr. Philippe Froguel of Imperial College and CNRS. “Epidemiological studies have shown that 80 percent of the risk of cardiovascular disease is related to a blood glucose level just above the average.” The researchers propose that the three SNPs they identified &#8220;are likely to have a non-negligible impact on human health.&#8221;
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Genetic Factors Related to Blood Glucose

<img decoding="async" src="https://blog-api.23andme.com/wp-content/uploads/2008/04/siegeofacre1291.jpg" alt="siegeofacre1291.jpg" class="right alignright" />Generally, the DNA in a man&#8217;s Y-chromosome contains information about prehistoric migrations that happened many millennia in the past. But a recent study of men in Lebanon shows that genetics can be a reflection of more recent events as well.
A paper published in the April issue of the American Journal of Human Genetics shows that two major events in the history of religion — the spread of Islam and the Crusades — have left their mark on Lebanon&#8217;s male population.
The authors of the AJHG paper showed that a disproportionate percentage of Muslim men in Lebanon have Y-chromosomes of a type that is common on the Arabian peninsula. Migrants from Arabia brought Islam to Lebanon during the 7th century.
Similarly, a disproportionate number of Lebanese Christian and Druze men have Y-chromosomes similar to those found in western Europe. In fact, the most common Y-chromosome signature in Lebanon is most abundant in France, Spain, northern Italy and the Low Countries. But it is found nowhere else east of Hungary.

The authors of the AJHG paper attribute that remarkable genetic connection to the Crusades, a series of military campaigns by European invaders against Jerusalem and other cities of religious significance in the Near East.
There is also an indication that men from Turkey introduced their genes into the Lebanese population during the time of the Ottoman Empire, which ruled Lebanon from the 16th to 20th centuries.
In most countries, geography is the most significant factor influencing the genetic variability of the population. But in Lebanon, religion accounts for more than three times as much genetic variation as geography.
&#8220;Such structure might arise only when several unusual criteria are met,&#8221; the AJHG paper concludes. &#8220;Migrations based on religion must take place between areas with different representative Y-chromosomal types, and they must establish genetically differentiated communities that remain stable over long time periods. In Lebanon, these conditions appear to have been met for over 1,300 years.&#8221;
&#8220;The Siege of Acre&#8221; by Dominique Louis Papety (1815-1849)

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