Study Finds Major Problem with At-Home Genetic Tests
Direct-to-consumer (DTC) genetic testing is having a moment. 23andMe just got FDA approval to test for BRCA mutations, which means that for the first time, the general public can test themselves for some of the known mutations that increase the risk of breast, ovarian, and prostate cancer. Thing is, genetic experts have consistently warned that these at-home tests have limitations and may not be as accurate as they appear. (BTW, 23andMe is just one of several companies that offer genetic testing for breast cancer at home-although it's the only one that doesn't require a doctor's prescription.)
Now, new research sheds light on exactly how inaccurate at-home tests might be. A new study in the journal Genetics in Medicine took a look at 49 patient samples that had been sent to a leading clinical genetics lab, Ambry Genetics, to be double-checked after an at-home test had already been performed. This practice, called "confirmatory testing," is generally recommended by health care practitioners when someone receives their results from an at-home genetic test. Often, confirmatory testing is requested by a primary care physician after a patient asks for help interpreting their raw data report.
This "raw" data generally needs to be interpreted by a third-party lab to be confirmed and understood correctly-a step that a lot of people skip. In this study, researchers collected as many confirmatory testing requests as they could find and compared their own analysis of patients' DNA to what the at-home testing results reported. Turns out that 40 percent of the variants (i.e., the specific genes) reported in the data from at-home tests were false positives.
Essentially, that means that gene variants the at-home tests identified in the raw data-both low-risk and high-risk ones-were not confirmed by the clinical genetics lab. What's more, some of the gene variants identified as "increased risk" genes by at-home tests were classified as "benign" by the clinical lab. That means some of the people who received "positive" results from their tests were *not* actually at an increased risk. (Related: Does At-Home Medical Testing Help or Hurt You?)
Genetic counselors aren't surprised. "I'm glad that the numbers are showing high rates of inaccurate readings so that more consumers will be aware of the inherent weaknesses in DTC genetic testing," says Tinamarie Bauman, a board-certified advanced genetic nurse and assistant director of the high-risk genetics program at AMITA Health Cancer Institute.
The solution: Talk to your doctor about seeing a genetic counselor. "Genetic counselors do more than just assess risk; they help you understand more about a positive or negative result," Bauman says. "Anyone who takes a DTC test and then receives the raw results can tell at a glance that there is much to be reviewed and interpreted."
If you really *do* have an increased risk for hereditary disease, a genetic counselor can help you take action to potentially reduce your risk, diagnose it earlier, or provide more informed and personalized treatment if necessary.
And even though Bauman's advice to consumers about DTC tests was the same before this study came out, it now feels even more urgent-especially for those who might have a genetic predisposition to cancer. "I work in oncology, and I'm very concerned about at-home testing for cancer genes," she says. "There's a great chance for potentially life-altering false-positives and negatives."
So if you've already received results from an at-home genetic test, getting confirmatory testing is essential, she says. "It is imperative to confirm all DTC raw data variants in an experienced clinical laboratory," Bauman notes. It's also important to understand the benefits and limitations of the test, and the possible consequences of the results. What will you do if the result comes back positive? What will it mean if it's negative? "Informed consent is an essential part of the process," Bauman says. "A consult can eliminate the confusion."