Monday, May 17, 2010

DTC genetic testing: Caveat Emptor

I met Cynthia in a van from the airport, headed to the annual meeting of Family Tree DNA (, 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 (, to learn about her ancestry. She got that, and more – health information, including a “lower than average” risk of developing diabetes. deCODE Genetics ( 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.    To top that off, I got a call from a writer for a popular psychology magazine asking me for a “sound bite.” A sound bite? Genetic testing isn’t quite that simple.

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.]


Sue Trinidad said...

What was the value to Cynthia of genetic testing for diabetes risk, in light of the fact that she had already been diagnosed with diabetes? What additional information does a genetic "diagnosis" provide in a case like this, either to the patient or her family? Is it really more definitive than the very strong family history she already knew about?

Ricki Lewis said...

Cynthia sent her sample for ancestry testing, and the company sent back a health profile that she did not ask for! This is exactly what I had lectured about. I was concerned with a client's right not to know. For example, I do not want to know if I have the apoE4 allele associated with elevated Alzheimer risk. I'd be looking for a lawyer if a company tested me for that without my consent. But the people at the conference accused me of paternalism. Cynthia said that their mindset is that it is their DNA and they have a right to know anything about it. But Cynthia's health related predictions were without her consent. Interesting set of issues!

Sue Trinidad said...

Fascinating - thanks for sharing the backstory on this!

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