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Autosomal Test Reveals Ancestry

A Work In Progress by Herbert Holeman, PhD.

This draft workpaper was last modified .

Findings to date.

• Autosomal testing reveals my ancestry is mostly Asian, following in order by European and Latin American.

• Estimates of my ancestry at the continental level are relatively consistent among DNA companies.

• There are no established guidelines among DNA service providers for the representation of ancestry.

• Deep ancestry reference populations are needed as current sampling is essentially based on present-day populations.

Discussion.

Research to depict ancestry began for me with the autosomal (atDNA) tests. From the test kits I submitted, there is a consensus of my ancestral admixture. As for its accuracy, I concur with genealogist Betty Bettinger, "the estimate is good on the continental level. Getting down to the country or region is much more problematic." "If a test-taker is just interested in finding out where there are some people in the world that share the same DNA as them, then these tests can certainly tell them that," adds anthropological geneticist, Dr. Deborah Bolnick.

Ancestry

Geographic population boundries vary by company. To that point, companies differ in delineating the geographical, political boundaries to calculate the population admixture percentages they assign to test-takers. Arguably, this accounts for much of the variance among the companies. Table 2 is one example of such differences. For Iberia, the 23andMe Company combines the population count of Spain and Portugal, while the Ancestry Company lists the population count individually for Spain, Basque, and Portugal.

Ancestry

Ethnic assignment in describing populations differs among companies. Genetic genealogist, Kitty Cooper points out, sometimes East Asian Ancestry is, in reality, American Indian, and South Asian might be Gypsy or Indian from India. Scandinavian might be British or North German, and British and Irish might be Scandinavian.

Note the labels in Table 3 to report an ancestry estimate from all four companies. The term Native American, used by 23andMe.com, is the most inclusive. But, for localizing ancestry, it is less definitive both ancestrally and geographically because it encompasses North, Central, and South American ancestry. Most definitive are the labels used by Ancestry.com.

Ancestry

Population timeframes for testing DNA differs among companies. Companies come at ancestry timeframes from different perspectives. For the most part, the companies 23andme and Ancestry are oriented on recent genealogy, around 500 years ago. In contrast, the XCode Company and FamilyTreeDNA Company strive to give ancestral information deeper than 500 years. Yet, to learn such deep ancestry, geneticist, Razib Khan points out Europeans as we understand them today, genetically did not exist 10,000 years ago. Descriptively, the same applies to South Asia (Afghanistan, India, Pakistan, Bangladesh, Sri Lanka, Nepal, Bhutan, and the Maldives).

A consensus of scientists share khan's view. In his article, Ker Than writes, "such tests cannot account for recent migrations of peoples from their ancient homelands. Present-day patterns of residence are rarely identical to what existed in the past, and social groups have changed over time, in name and composition." Moreover, "For deeper family roots, these tests do not really tell you where your ancestors came from. They say where DNA like yours can be found on Earth today," adds noted geneticist Dr. Adam Rutherford.

Yet, my research interest conversely calls for sampling deep ancestry. It requires a type-population in a given geographical region with a good DNA profile of ancient people. Such a population is one without admixture, a sampling population composed of pure-bloods from the tested region.

Disproportionate Sampling is another issue. Test populations are not in proportion to the global population. People of European Ancestry make up less than 25% of people worldwide. Yet, they represent most of the participants in the genetic research of companies. Mark Thomas, professor of evolutionary genetics at University College London adds "The databases are skewed towards different parts of the world, too. The 23andMe Company has more American customers, and AncestryDNA Company has more British and Australian."

These companies have an extensive Eurocentric database but relatively small and limited Asian reference populations for estimating ancestry. Even so, as Figure 3 shows, these companies continue to refine their estimations of ancestry by expanding their reference population databases for global coverage, including Asian populations.

Figure 3. Measuring company databases. ancestry

Fortunately, there are three companies currently serve the people of Asia, which accounts for ~60% of the world's population. One such company is XCode. It is based in India and claims to cover 23% of the world's population of South Asia heritage. This area includes the 1.75 billion people of Afghanistan, Bangladesh, Bhutan, India, Maldives, Nepal, Pakistan, and Sri Lanka.

Two other companies, WeGene and Zuyan, based in China serve the 1.6 billion people who live in East Asia and make up 38% of the world's population. These are China, Mongolia, North Korea, South Korea, Japan, Hong Kong, Taiwan, and Macau.

These two companies also cover 9% of the world's population who live in Southeast Asia. It includes Brunei, Cambodia, Southern China, Indonesia, Laos, Malaysia, Myanmar, Philippines, Singapore, Thailand, Timor Leste, Vietnam, Christmas Island, Cocos Islands. The WeGene company boasts an extensive Asian reference population database and specializes in the genetic exploration of Asian heritage. WeGene's analytical algorithm uses machine learning based on the Admixture ancestor analysis tool developed by the University of California (UCLA), Los Angeles.

In any case, ancestry estimates will likely differ among companies because their sampling reference differ. Each company relies on its proprietary database for DNA reference sampling. There are no established guidelines for the representation of ancestry.

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