Study Warns Direct-to-Consumer Genetic Tests Have False Positives

But 23andMe says this new paper doesn't disqualify its findings.

Direct-to-consumer genetic tests have changed the average person’s relationship to their DNA, altering genetic code from an inaccessible science to a play-by-play of probable ancestry. But some scientists are concerned that the rising use of DTC tests as a means to pinpoint the chance of developing certain conditions or one’s carrying status for recessive diseases pose an overall danger to public health.

In a new study, scientists from Ambry Genetics Corp., a private clinical diagnostics lab, warn that buried within the raw data provided by DTC tests are false-positives that can come with big implications.

When most DTC companies send a consumer back their results, they typically send two sets of information: One is interpreted by the company, like how closely you are related to Neanderthals and what parts of the world your ancestors came from, and the other is all the raw genetic data determined by your DNA sample. In the March edition of Genetics and Medicine, the Ambry Genetics scientists explained that they examined the raw data belonging to 49 patient samples. Each data set contained genetic variants reported by the several DTC companies that provided that data — mutations that could be indicative of a health risk.

After Ambry Genetics analyzed the same data, they discovered a 40 percent false positive rate within the variant findings, which study lead Stephany Tandy-Connor, M.S., explained in an accompanying blog highlights “the importance of confirming DTC raw data before making any medical decisions.”

“With the ever-growing shortage of genetic counselors and other highly trained genetic professionals, there is concern regarding how DTC test results are interpreted and used among medical providers who often have minimal genetic training,” Tandy-Connor and her co-authors write. “It is therefore imperative that consumers, as well as their medical providers, are aware of the wide array of limitations to this type of genetic testing, especially in regard to an individual’s clinical management.”

The pie-chart on the right, the study states, "shows which genes were involved with the false-positive cases and how often those false calls were detected."

Stephany Tandy-Connor

But what exactly does this mean for consumers who have helped turn genetic testing into a million-dollar industry? When it comes to 23andMe, which announced in March that it became the first FDA-authorized DTC company to provide information on genetic variants found on the BRAC1 and BRCA2 genes — which are associated with a higher risk for breast, ovarian, and prostate cancer — it allegedly doesn’t give cause for concern.

“The study looked at how third-party services outside of 23andMe interpreted raw data from 23andMe and many others — this is not the information we interpret for consumers in 23andMe reports, rather third parties interpreting ours and others’ raw data files,” 23andMe spokesperson Andy Kill tells Inverse. “The health data we report back and interpret for consumers undergoes an incredibly rigorous, FDA-mandated accuracy review process — much more rigorous than this study which only used 49 samples from several different companies, whereas we test hundreds of samples.”

Test kit for genetic testing by 23andMe.

Wikimedia Commons

Kills also points out that the only variants this study comments on that 23andMe plans to include in its own health reports — the ones that apply to BRAC1 and BRCA2 genes — came back as 100 percent positive.

What this new study comes down to is the question of the accuracy of the massive raw data files given to customers and whether or not those customers should be taking that data to third parties for interpretation. At 23andMe, a DNA chip test scans for 600,000 or so different genetic variants and customers can download the accompanying raw data to know every kind of variant on that chip.

“Part of our ethos is that as a customer you own your data, so we give you the option to download the entire file which is separate from the information that we’re actually interpreting and reporting to you as far as health and wellness,” says Kill.

That information is subject to rigorous FDA testing, as opposed to the raw data as a whole. The point that this new study is making is that, although DTC companies do not provide interpretation of the raw data, patients can take the data to third-party labs and ask for analysis, and “the misinterpretation and potential inaccuracy of the raw data pose substantial risks to individuals who obtain this type of information from a DTC company.”

Here, genetic data is more Pandora’s box than time-machine — but it’s really on the customer to do act smartly with data not designed to be analyzed.

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