A recent announcement from the U.S. Food and Drug Administration clears the way for companies to bring genetic tests to market faster—including direct-to-consumer tests, which have long been reined in by strict FDA guidelines. While this is a big step forward for consumers eager to be more engaged in managing their own health, there are reasons to keep a healthy dose of caution on hand.
Today, people are encountering genetic testing more than ever before. Beyond the soaring number of tests available through doctors for everything from carrier screening, to cancer risk susceptibility, genetic tests for ancestry, and other non-medical uses have even brought these products to NFL stadiums as crowd giveaways. DNA kits were featured on Black Friday and will be on many holiday gift lists this year.
At the same time, we’re seeing an uptick in lawsuits around erroneous results from genetic tests, and some politicians are raising concerns about privacy. In Oregon, a woman underwent a prophylactic double mastectomy and hysterectomy upon learning her high risk of getting cancer, but later found out that the genetic test was misinterpreted and she was never at such risk. She is suing her doctors and other health officials for $1.8 million. In Australia, a couple recently settled with a fertility clinic after the wrong test was used to determine whether the prospective mother was a carrier for fragile X syndrome. The results came back negative, but the parents gave birth to two sons who had the condition.
Some cases stem from negligence, while others arise from situations where the state of genetics simply isn’t advanced enough to determine with certainty what recipients of results are being told. As genomic testing is being aggressively marketed to consumers, it is a good time to consider just how reliable our knowledge of DNA actually is.
We can learn a lot from the world of infectious disease. Back in the 19th century, when scientists were trying to determine which microbes caused which diseases, there were lots of bad calls. In order to ensure that a microbe really, truly caused disease and wasn’t just a harmless passerby, scientists came up with a rigorous process involving all sorts of validation. Essentially, if your work could clear the bar set up by these rules, you had proven beyond the shadow of a doubt that a specific pathogen was the cause of a specific disease.
This level of rigor has not yet been met in genomics. It’s not that we won’t achieve it. It’s just really, really early. Today, scientists are performing amazing studies designed to find genetic variants associated with diseases or other biological traits; this is like finding a microbe that looks like a promising suspect for a particular infectious disease. But the follow-up studies—the ones that offer incontrovertible proof that these variants cause the disease—are much harder to come by.
So now we have a wealth of DNA variants that seem likely to cause disease, but much evidence must still be gathered. Some variants have been thoroughly vetted and verified, but most are in the gray area. And it’s not uncommon to see variants that were thought to be confirmed as disease-causing get overturned after further study; sometimes they just travel along with the real causative variant, but they’re actually harmless.
In all the excitement surrounding genetic tests, it can be hard to remember that the science behind them is still evolving. New discoveries are happening all the time, and sometimes they force researchers to reinterpret things they thought they already knew. This is the messy part of science that usually stays behind the curtain, but it is being brought to the fore as people begin to make major medical decisions based on genetic results. Is genetic testing ready for consumer consumption? If marketing races ahead of reality, there is a very real risk that the missteps could impede its promise.
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