New Study Warns That Home DNA Kits Often Fail to Detect Certain Breast Cancer Genes

It turns out, 23andMe comes with a huge asterisk.

Home DNA kits have become incredibly popular these days. Want to learn about where your ancestors came from? Send a cotton swab over to AncestryDNA. Looking to find the best way to lose weight based on your genes? HomeDNA's got you covered. But if you thought sending in a saliva sample could determine whether you're more at risk of breast cancer or not, think again.

Researchers at genetic information company Invitae looked into 23andMe's BRCA test, which claims to test for three common variants in the BRCA1 and BRCA2 genes that indicate an increased risk of breast cancer. But the researchers found that the company's at-home test misses almost 90 percent of instances. When the study authors instructed more than 4,700 patients with a known BRCA1 or BRCA2 mutation to take an at-home test, only 12 percent received positive results. The other 88 percent? Their mutations fell into the 1,000+ that 23andMe doesn't test for.

23andMe's at-home mutation tests have long been criticized, but Invitae's study—presented this month at the American College of Medical Genetics and Genomics annual meeting—is the first to show just how limited they really are.

Though 23andMe's BRCA test is authorized by the Federal Drug Administration, the organization warns that "a negative result does not rule out the possibility that an individual carries other BRCA mutations that increase cancer risk." They also claim that the results of the test "should not be used as a substitute for seeing your doctor for cancer screenings." However, many consumers simply receive a negative result and think they're in the clear.

"People have the right to their own genetic information, but with that right comes a responsibility," Dr. Robert C. Green, a professor at Harvard Medical School, told the New York Times. "If you are going to go around the medical mainstream, read the caveats."

23andMe has responded to the study, calling many interpretations of Ivitae's findings "misleading."

"Helping people understand their genetic information is core to our mission and we are very clear with our customers that our BRCA1/BRCA2 report only tests for three out of thousands of possible genetic variants in these genes," Jeffrey Pollard, MD, 23andMe's director of medical affairs, said in a statement. "23andMe tests for these variants because they are three of the most well-studied and carry clear, documented risk for breast and ovarian cancer. … As part of the FDA review process, we demonstrated that our test is over 99 percent analytically accurate for the genetic health risk reports we provide."

And if you're worried about your breast cancer risk, check out these 40 Ways to Prevent Breast Cancer After 40.

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