Conference Coverage

Direct-to-consumer genetic testing fraught with validity concerns


 

EXPERT ANALYSIS FROM INTERNAL MEDICINE 2019

– There are real concerns about whether today’s direct-to-consumer (DTC) genetic tests actually test the mutations they claim to test and of how well a tested DNA sequence tracks actual disease, Andrew D. Coyle, MD, said during a podium presentation at the annual meeting of the American College of Physicians.

Many patients don’t tell their doctors the results of DTC tests, and there’s a lot of potential for misinterpretation all around, said Dr. Coyle, assistant professor of medicine and medical education in the general internal medicine division at the Icahn School of Medicine at Mount Sinai, New York.

“I wouldn’t recommend to patients that they do [DTC testing], if they asked,” he said. “I think we probably do need to be better about asking our patients whether they’re doing this on their own, to make sure that we help them interpret it correctly, that it’s a change in risk – not a diagnosis, and not an assurance they won’t get that disease process.”

High false-positive rates have been seen in recent studies that sought to confirm genotyping data from DTC genetic test results, according to Dr. Coyle. In one 2018 study in Genetics and Medicine (2018;20:1515-21) of 49 patient samples tested for previously identified genetic variants found in raw DTC data, investigators found a 40% false positive rate, which they said underscored the importance of clinical confirmation testing to assure proper patient care, he noted.

To support his claim that many patients aren’t even telling their doctors about the DTC testing they are having done in the first place, Dr. Coyle mentioned results of a survey in Annals of Internal Medicine (2016;164[8]:513-22), which showed that only 19% of patients shared their DTC results with their primary care physicians.

He also pointed out a potential problem regarding the discussions between patients and their physicians about these test results, based on another finding reported in the paper. Of those who did tell their physicians they had DTC testing, 35% said they were “very satisfied” with how that discussion went, Dr. Coyle said.

“So they don’t tell us, and they aren’t very happy when they do tell us,” he told his audience.

The 23andMe test and the FDA

The 23andMe test, which was first directly marketed to consumers in 2006, was one of the DTC genetic tests discussed by Dr. Coyle. The Food and Drug Administration later halted the company’s Personal Genome Service in 2013 because of a lack of demonstrated clinical validity, Dr. Coyle noted.

Subsequently, the FDA classified carrier-screening tests as medical devices, allowing such services to come back, leading to what Dr. Coyle described as an explosion over the past few years of DTC evaluation of a variety of conditions, including celiac disease, Alzheimer’s disease, hemochromatosis, and then more recently, screening for cancer risk factors.

In 2018, 23andMe began offering DTC BRCA testing, but for 3 BRCA1/2 mutations seen in individuals of Ashkenazi Jewish descent, Dr. Coyle said.

“If someone did a BRCA test which is only testing three specific mutations seen mostly in Ashkenazi Jewish populations, they may be falsely reassured that the risk of breast cancer is low, when in fact they may have other BRCA mutations,” he said.

In real life, however, many people who order genetic tests online may not even act on the results. In a 2017 study in the Journal of Clinical Oncology, customers whose DTC genetic testing results showed elevated cancer risk were no more likely than were customers without elevated risk to change diet or exercise, engage in advanced planning behaviors, or get screened.

Dr. Coyle had no relevant disclosures to report.

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