Women can now buy a test telling them if they carry variants of the BRCA1 and BRCA2 genes that raise their risk of breast cancer. That sounds like a welcome advance in medical technology. But the particular variants identified are mostly confined to Ashkenazi Jewish women and are very rare in the general population. If women buying the new test don鈥檛 understand that, there is a risk they could be lulled into a false sense of security if they test negative.
The test is being sold by , a Californian company that has pioneered personal DNA analysis. The US Food and Drug Administration听(FDA) approved the test鈥檚 sale yesterday, and if you have recently submitted your DNA to 23andMe, the results should be available online soon to customers who specifically request them.
But should you look at them? There are more than 1000 known mutations in the听BRCA1听补苍诲听BRCA2听genes, but the new test only detects three. They are carried by 1 in 40 people of Ashkenazi ancestry, compared with 1 in 400 in the general population, and are thought to pose a high risk for carriers, giving them a 45 to 85 per cent chance of developing breast cancer and a 39 to 46 per cent risk of developing ovarian cancer.
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In the general population, however, doctors regularly test women for other well-established common variants of听BRCA1听and听BRCA2. Around听. The 23andMe test will tell you nothing about these variants.
Not gospel
The company is adamant that women testing positive for any of the three gene variants shouldn鈥檛 take this as gospel, but should seek further advice. 鈥淲e state clearly in the results that if you have one of these variants, you should see a healthcare professional and seek confirmatory testing,鈥� says a 23andMe spokesperson. 鈥淭hese mitigations were required by the FDA.鈥�
Previously,听23andMe has been in trouble with the FDA. In 2013, 听that claimed to reveal gene variants linked with conditions such as diabetes and cardiovascular disease. The decision was made on the grounds that people might seek drastic medical treatment based on the tests.
More recently, the FDA鈥檚 stance has shifted. A year ago,听听that claimed to听flag up the risks of 10 conditions, including late-onset Alzheimer鈥檚 disease and coeliac disease. In November 2017, the FDA announced a听relaxation in the requirements for direct-to-consumer gene tests and said it would favour applications from companies that had previously applied successfully, a move that should help 23andMe.
The FDA says that strict conditions called听听apply to the new breast cancer test. 鈥淭hey include not using the test to determine medical treatments, which would require confirmatory testing, and consulting with a physician to discuss test results,鈥� a spokesperson told听91av.
But will that message get through to consumers, particularly those who have already submitted their DNA and will be able to just see the test results when they appear online? That remains to be seen. 23andMe is taking the risks seriously and says that its customers will be given an 鈥渆ducation module鈥� along with the results that details how they should be used. 鈥淭he information from the test can be life-changing,鈥� says the firm鈥檚 spokesperson.
