Don’t panic over your online gene test

False positives not uncommon when dangerous mutations are found

Dr. Joshua Clayton, a 29-year-old radiology resident at Baylor University Medical Center in Dallas, wanted to learn about his ancestry. So he sent a sample of his saliva to 23andme, the genetic testing company. His report was pretty mundane — no new revelations. But then he sent the profile created by 23andme to a separate company called Promethease, which promises to do a more in-depth analysis for genetic mutations that cause disease. The news was not good. Clayton got back a report with a sinister red box at the top saying he had a mutation linked to Lynch syndrome, a frightening genetic disorder that leads to potentially deadly cancers at an early age.

In an interview, Clayton said he another genetic test at a company with “knew, at least cursorily, that false positives expertise in medical diagnostics, he were common with these tests.” learned the red box result was wrong. But “that didn’t change the frightened He simply didn’t have the mutation. feelings or concern, because I certainly More Americans are embracing couldn’t blow it off.” consumer genetic testing, but the

After two weeks of panic and yet Food and Drug Administration limits what major firms like 23andme or ancestry.com can say about a consumer’s health.

So, many people are taking an additional step: uploading all the raw data created by these companies to second companies for additional analysis. But these are not firms certified to provide medical diagnoses, nor are they sophisticated academic centers.

Companies like Promethease warn customers not to regard their results as medical diagnoses. Mostly, they are comparing a consumer’s raw data to gene variants reported to be linked to disease.

But it’s not at all clear that consumers understand how uncertain their results may be.

There are no systematic studies of how often the direct-to-consumer results and third-party analyses are wrong. In one small study, Ambry Genetics — a lab certified to do medi-