I met Cynthia in a van from the airport, headed to the annual meeting of Family Tree DNA (familytreedna.com), where I was to speak about genetic testing. A beautiful blonde who looked decades younger than her 60 years, she?d led a painful life, with type 1 diabetes since childhood, just like her father, brother, and grandfather. The family, so they thought, was 100% European, mostly Polish.
My talk did not go over well. Genetic testing companies and their customers do not like to hear that a geneticist thinks their tests should be regulated, for reasons of both privacy and accuracy.
Cynthia, intrigued despite my warnings, sent off a spit sample to 23andme (23andme.com), to learn about her ancestry. She got that, and more ? health information, including a ?lower than average? risk of developing diabetes. deCODE Genetics (http://www.decodeme.com/) gave her the same answer. Ditto her brother.
But her brother?s Y chromosome held an explanation. About 1200 years ago, a Korean man and at least two Chinese men dropped a bit of DNA into the family. So when Cynthia went back to 23andme and recalculated, entering ?Asian? instead of ?European,? her diabetes risk shot up to 90%.
So it looks like ancestry testing helped get this family on the right track. But another way to look at it is that the health-related tests are simply not precise enough.
This past week ?direct-to-consumer? genetic testing took a hit, and it?s about time. First the Walgreen?s near-fiasco of off-the-shelf direct-to-consumer genetic tests, then a white paper from the American Society of Human Genetics calling for oversight of ancestry testing.
Genetic tests for well-studied mutations, delivered by a genetic counselor or physician, in person, are fine. But the genetic ?associations? gleaned from population data, although useful in research, often cannot reveal much of anything about an individual ? such as Cynthia.
Caveat emptor.
[cross-posted from Ricki Lewis' blog, GeneticsWatch.]
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