Personal genetics company 23andMe received approval for a genetic test for three of the roughly 1000 mutations in the BRCA1 and BRCA2 genes that are associated with an increased risk of developing breast, ovarian and prostate cancer. While these mutations are common in people of Ashkenazi Jewish descent, with one in 40 individuals carrying them, they are rare in the wider population.
The new test 'has a lot of caveats', said Donald St. Pierre, at the FDA's Centre for Devices and Radiological Health. '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.'
Women with the genetic variants assessed by 23andMe's test have a 45-85 percent higher chance of developing breast cancer by the age of 70. 'This authorisation is incredibly valuable for those who might not be aware of their Ashkenazi Jewish descent or aren't familiar with their family history of cancer,' said Anne Wojcicki, CEO and co-founder of 23andMe.
But Wojcicki, along with the FDA and other experts cautioned that a negative report from 23andMe on these three BRCA mutations does not exclude the possibility of a person carrying another BRCA mutation associated with an increased risk of developing cancer. 'For other groups with different […] mutations, and there are many, it won't help much. There's a big need for users to understand that nuance, which is not widely understood,' Dr Robert Cook-Deegan at Arizona State University, told STAT.
23andMe's test relies on a saliva sample to test for the BRCA mutations. Normally, only women with a family history of breast cancer get referred for genetic testing to investigate their BRCA status. If mutations which increase the risk of developing cancer are found, preventive measures include regular check-ups, potential lifestyle changes and possibly preventive surgery.