Bay Area DNA firm gets OK on cancer risk test
The Food and Drug Administration on Tuesday authorized Mountain View’s 23andMe to sell a test for a breast cancer genetic mutation directly to consumers — the first time the agency has allowed the sale of a genetic test for cancer risk without a doctor’s prescription.
The test covers only three of the thousands of variants on the BRCA1 and BRCA2 genes that are linked to increased risks of cancer. Nonetheless, it reflects regulators’ growing willingness to make genetic testing more accessible to consumers.
The test analyzes a saliva sample to determine whether a person has an increased risk for developing breast cancer by detecting three variants on the BRCA1 and BRCA2 genes. These three variants are most common in people of Ashkenazi Jewish descent, where women with one of the variants have a 45 to 85 percent chance of developing breast cancer by age 70. The three mutations are not the most common BRCA mutations among the general population.
This means that if a person tests negative for the three variants on the 23andMe test, they could still carry other variants, on the BRCA or other genes, that could increase their risk of inherited breast and ovarian cancer.
Many of 23andMe’s tests for genetic mutations linked to other diseases, such as celiac disease and a blood-clotting disorder, have been available to consumers without a prescription for a year. But 23andMe CEO and co-founder Anne
Wojcicki said that the FDA’s move to add the cancer test was “a major milestone” for the company and for consumers.
23andMe had offered BRCA testing for the same three variants prior to 2013, but suspended the service after the FDA that year issued a warning letter saying the company had not provided enough data to show its tests were accurate, and expressed concern that people might use the test results to make medical decisions.
About 10 percent of diagnosed breast cancers are inherited. Within that 10 percent, about half are due to a BRCA1 or BRCA2 mutation. Other genes linked to an increased risk of inherited breast cancer are ATM, CHEK2 and PALB2.
To determine whether one carries the thousands of other variants on the BRCA1 and BRCA2 genes, patients must get a doctor’s approval. And if they want their insurance to pay for the test, it must also have to be deemed medically necessary. Typically, a BRCA test is not recommended unless someone has a family history of a relative with a BRCA mutation, are of Ashkenazi Jewish descent, or had breast cancer before age 50.
The BRCA test is now included in 23andMe’s $199 “health and ancestry” test, which analyzes genes related to a number of inherited conditions, including cystic fibrosis, sickle cell anemia, hereditary hearing loss, Parkinson’s and Alzheimer’s.
Several other companies sell genetic tests that analyze BRCA genes for variants, but they must be ordered through a doctor. They are also more comprehensive than 23andMe’s test because they analyze a larger portion of the genes. Burlingame’s Color Genomics, for instance, sells a $99 BRCA test that screens for 5,500 variants; consumers can buy it
directly from Color or retailers like Amazon.com, but a doctor must approve the order. Salt Lake City’s Myriad Genetics makes a hereditary cancer risk test that analyzes 28 genes, including BRCA1 and BRCA2; it too must be ordered by a physician.
The FDA authorization of 23andMe’s test “is a step forward in the availability of (direct-to-consumer) genetic tests,” Donald St. Pierre, acting director of the FDA’s Office of In Vitro Diagnostics and Radiological Health, said in a statement. “But it has a lot of caveats. While the detection of a BRCA mutation on this test does indicate an increased risk, only a small percentage of Americans carry one of these three mutations, and most BRCA mutations that increase an individual’s risk are not detected by this test.”
The test should not be used as a substitute for seeing a doctor for cancer screenings or counseling on genetic and lifestyle factors that can affect cancer risk, St. Pierre said.
“The most important thing for people to understand is this test is not a test a doctor would use,” said Bryce Mendelsohn, a UCSF geneticist and physician who treats patients with genetic conditions, including developmental disabilities and metabolic disorders. “It’s good to get (people) engaged and thinking whether genetics have a role in their health care, that’s a positive, but it’s not a substitute for a clinical workup.”