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Biomedicine

A Genetic Christmas Story

Beyond a novel new way to track down your family history, home DNA tests may help unlock the history of humans.

Some people may have received an unusual gift this holiday season: an ancestry testing kit that uses a small swab of DNA to shed light on near and ancient family history. It sounds, at first, like a novelty item. But the kit may provide long-term assistance to scientists who are hoping to track the history of the human race.

In one project, spearheaded by National Geographic Society and IBM, participants buy a kit for $99.95, scrape some skin cells from the inside of their cheek, and send the samples in for analysis. Once the DNA is processed, participants learn their haplogroup – the specific branch on the tree of early human migrations and genetic evolution that their maternal or paternal ancestors belong to. They’ll also get a map of the migration routes of those deep ancestors.

Other companies sell kits to test more recent family history. “It’s a novelty educational gift – you learn some history about Homo sapiens and maybe some genealogical information,” says Bennett Greenspan, president of FamilyTreeDNA, a DNA genealogy testing company based in Houston, TX, which partners with National Geographic. “Sales figures as holiday gifts are through the roof.”

The National Geographic kit is just one part of a large-scale research effort, called the Genographic Project, to trace the migratory history of the human species. Scientists will study DNA markers in both indigenous populations across the world and in public participants who want to learn more about their own origins.

IBM is building a large database to house data from both the public participation and indigenous populations under study in the project. “As more people participate, we can compare the sequences we obtain in a greater degree of detail and identify smaller sub-branches on the tree,” says Ajay Royyuru, the IBM scientist who heads the research component of the project. IBM and National Geographic plan to release the scientific findings to the public over the next five years.

While the National Geographic kit analyzes deep ancestry, which can tell how an individual’s distant ancestors migrated out of Africa, other tests can shed light on a person’s more-recent family tree, for example, estimating the percentage of ancestry that is tied to Europe, Africa, Asia, or the Americas, or how closely related an individual is to someone else with the same last name.

FamilyTreeDNA, Relative Genetics, a genealogy company based in Salt Lake City, UT, and DNAPrint genomics, a genetics company based in Sarasota, FL, all have offered DNA tests, as well as deep ancestry tests, for several years. Interest has soared, they say, for two key reasons: testing costs have decreased and people have become more aware of the possibilities of DNA.

“The idea that people are interested in this scientific approach to their origins is very interesting, especially since it implies an acceptance of migration and evolutionary origins,” says Peter Byers, president of the American Society of Human Genetics. “This may allow us to see that people, no matter how different they look or behave, all have a similar origin.”

Byers also cautions that the information in many tests is limited. For example, the most common ancestry tests analyze DNA from the Y chromosome for men and mitochondria for women. Because the Y chromosome is only passed through the male lineage (a father’s father’s father’s…), it gives information only on that line, ignoring genetic contributions from the other three grandparents.

Byers adds that the accuracy of the tests depends heavily on the data used to interpret differences in DNA. For example, genetic data from indigenous populations – which have stayed in the same location and undergone relatively little gene mixing – can help scientists predict how the ancestors of a person who shares some of those markers moved around the world.

Jim Feaser, an oil economist from Houston, TX, recently caught the DNA ancestry bug. He found a not-so-distant relative living across town – after recruiting 15 other people with his last name to get DNA tests.

Last year, Feaster and his wife went to a family reunion of their newly found relations. “We acted like we were cousins,” says Feaster, who first became interested in deep ancestry testing after watching a PBS special on Spencer Wells, the population geneticist who’s leading the Genographic Project. According to the test, the two Feasters share a common ancestor within the last few hundred years. They’re now trying to track down that common ancestor to verify the DNA link.

How DNA Home Testing Works
For men only: Paternal Line analysis compares DNA markers on a part of the Y chromosome that is passed stably from fathers to sons. It can be used only by males (since only men have a Y chromosome). One subset of the DNA markers can be used to indicate the haplogroup to which an individual belongs; another subset, to determine if two men are related.

For women and men: Maternal Line analysis compares DNA from the mitochondria, a component of the cell passed from mothers to children. Both men and women can use this type of test to study their maternal ancestry. The mitochondrial DNA used in these tests changes very slowly, so it’s more useful for studying distant relatedness, rather than recent family connections.

For whole populations: Autosomal analysis uses DNA from chromosomes other than the X and Y sex-linked ones. Scientists look for different markers that are associated with specific populations, such as Africans, Europeans, Asians, or Native Americans. These markers can also be used to determine the relatedness of two individuals and to create genetic family trees.

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