BRCA 1 & 2 genetic testing now more available
by Dr. Alan Kadish
You might remember when getting a BRCA test for the breast and ovarian cancer gene was a many thousands of dollar affair and only one company was the provider. Then in June 2013 the supreme court unanimously ruled that Myriad Genetics Inc’s , patent was invalidated. This lead to the overturning of all patents for the evaluation of naturally occurring genes.
Women who wanted to know if they are at risk for breast cancer can now find a test at a more reasonable price. Keep in mind that only 5-10% of breast cancers are directly related to BRCA mutations. Now for the new news, the FDA has approved 23&Me to do this testing with some considerations.
The story gets a bit murky about this point as you can’t just take some information from the test, extrapolate and be certain that you are or are not at risk. The exception is unless of course you are an Ashkenazi Jewish woman who has a family member with breast or ovarian cancer and the result is negative. This gal will sleep better at night knowing that risk is not in her code.
If you do a BRCA test, it’s important to know that there are many types of mutations in everyones genetic code. The key is to know which of the code problems could potentially become a health issue, such as a cancer. And it’s equally important to understand that even if you have what appears to be a high-risk mutation, it does not guarantee that you will develop any type of cancer. Not to make your job harder keep in mind that there are 5 types of mutations seen in doing genetic work.
- Deleterious mutation: The change is proven to cause significant risks.
- Suspected deleterious: While nothing is proven, the variation is currently believed to be harmful.
- Variant of uncertain significance (VUS): Whether the change has any effect is uncertain. This is a common test result, and most variations began in this category. As more evidence is acquired, these are re-classified.
- Variant, favor polymorphism: While nothing is proven, the variation is currently believed to be harmless.
- Benign polymorphism: The change is classified as harmless. These may be reported as “no mutation”.
Now for the rest of the story. Genetics is a fairly complex affair that is still very much in the infancy of both quality detection (reading the whole sequence) and understanding. In most cases science is still learning what really are the implications of most of the information. Many consumers assume improperly that the genetic tests are accurate to high precision levels and can be relied upon to give a clear path towards treatment or not.
Before you write off genetic testing keep in mind that overall the accuracy has been increasing logarithmically from the old style of devices only a few years ago to much more accurate outcomes and we are constantly learning of new combinations of both genes and their expressions. And if you do find a sequence that is indeed questionable you can have further evaluation done to verify if indeed it should/could be used to direct a therapy or change in your life style.
I think the 23&Me testing can be very helpful, with proper interpretation
Other information from their testing can be useful and is relatively inexpensive
If you have ANY questions about the interpretation you should request a consult with a genetic counselor
Opinion: No, FDA Didn’t Really Approve 23andMe’s BRCA Test
Rather, the breast cancer mutation screen was classified as a type of medical device with obligations for the company to reduce risks to customers.
March 19, 2018|
The biggest challenge, by far, will be to understand why and how the correct interpretation of DNA results can vary between people.
The FDA identified that this test presents a risk of an incorrect understanding of the test by consumers, false test results, and poor interpretation of the results. The agency requires that 23andMe puts “general and special controls” in place to reduce these risks. The company received a long list of warning statements, specifications, and limitations of the test that it needs to include in the labeling of the product and the pre-purchase information. The company is also required to conduct a user comprehension study to assure that consumers understand the material that is provided.
Whether the controls will help consumers to correctly understand and interpret the test and its results remains to be seen. The simple and uniform presentation of information that is needed to achieve that goal is at odds with the enormous variation in the quality, relevance, and value of scientific and clinical studies on which the test results are based. The biggest challenge, by far, will be to understand why and how the correct interpretation of DNA results can vary between people.
If you carry one of the three BRCA mutations, the interpretation is straightforward. It means that your breast cancer risk is much higher than that of other women. The significance of not carrying one of the three mutations depends on who you are.
If you are an Ashkenazi Jewish woman with a family history of breast cancer and your affected relatives carry one of the three mutations, then the absence of the mutation is an enormous relief.
If you are a non-Jewish woman, then the absence of these mutations means nothing, as you were unlikely to carry them at all. For you, getting screened is like taking a pregnancy test when you already know you are not pregnant.
And it also means nothing if you are a non-Jewish woman with a family history of breast cancer. The mutation that causes breast cancer in your family is likely one of the thousands of others that are known or one that is yet to be discovered.
The DNA test is equally accurate for all these women, but the value and effect of the test differ between them.
23andMe’s press release about the BRCA test does not mention “approval,” but correctly states that the company received FDA “authorization” to market the BRCA test. Also, in its advertising of the Genetic Health Risks and Carrier status tests, the two tests that the FDA allowed earlier, the company writes that each “meets FDA requirements.” But an authorized test that meets FDA requirements is not an FDA-approved test, and class II classification does not mean that the agency endorses direct-to-consumer genetic testing either. The FDA allows consumers to make their own decisions about genetic testing, including the bad ones. Time will tell whether those decisions are in consumers’ own best interests.
Cecile Janssens is a professor of Epidemiology at Emory University’s Rollins School of Public Health who studies the genetic prediction of disease.
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