The New York Times decided to publish an editorial this weekend warning people to "be careful about 23andMe's Health Test." What are they worried about?
Although the NY Times article is accurate, the warning suggests that 23andMe misleading its customers somehow. Is it? I decided to take a look.
I'm a customer of 23andMe, and I'm also a researcher in genetics and genomics, so I know quite a bit about how their technology works and about what it can reveal. I've looked at 23andMe's latest genetic health reports, and they are remarkably clear and accurate.
Let me illustrate by revealing part of my own genetic test results. First I looked at my results for BRCA1 and BRCA2, the two genes that the NY Times article discusses.
I don't have any of the harmful mutations in the BRCA genes, which 23andMe reports like this:
However, more than 1,000 variants in the BRCA1 and BRCA2 genes are known to increase cancer risk, so you could still have a variant not included in this test. In addition, most cases of male breast cancer and prostate cancer are not caused by inherited variants, so men without a variant are still at risk of developing these cancers."
Notice that they immediately provide the caveat that more than 1,000 other variants in these genes have been linked to cancer risk, and they make it abundantly clear that they didn't test any of those. Here's what the NY Times article said:
"The 23andMe test can miss other possible mutations.... there are more than 1,000 other BRCA mutations that contribute to your breast cancer risk. The 23andMe test doesn’t look for any of them."
A reader of the Times might think, upon reading this, that 23andMe somehow hides this fact. But the Times editors do little more than paraphrase 23andMe's own report.
The Times editors also caution that
"Just because you test negative for the few mutations that 23andMe screens for doesn’t mean that you won’t get breast cancer."
Duh. 23andMe explains this as well, and much more, such as:
"This test does not take into account other risk factors for breast, ovarian, prostate, and other cancers, such as personal and family health history." [from 23andMe]
The 23andMe report also provides a wealth of information about the BRCA genes, including links to the scientific papers describing the genes and their link to cancer. I was very impressed by how thorough they are.
The Times editors focused on the BRCA genes, but 23andMe also tests a handful of others (9, in my case). I looked at the APOE gene report, which has a mutation that has been linked to Alzheimer's disease. The bad variant is called ε4, and fortunately I don't have it.
Once again, the 23andMe site was very clear about what this means, providing a detailed table showing the risks for people with and without the mutation. In my case, they tell me that:
"Studies estimate that, on average, a man of European descent has a 3% chance of developing late-onset Alzheimer's disease by age 75 and an 11% chance by age 85."
Looking at the detailed table, one learns that if you have one copy of APOE ε4 variants, your risk of developing Alzheimer's by age 75 is 4-7%, and if you have 2 APOE ε4 variants–the worst case–then your risk jumps to 28%. The website provide links to 10 scientific papers with far more detail, for those who want to know the basis of these numbers. This is far more than most people will want to know, and I couldn't find any flaws in 23andMe's description of the science.
The Times editorial concludes with this:
"23andMe has said that its health tests can raise awareness about various medical conditions and empower consumers to take charge of their health information. But doctors and geneticists say that the tests are still more parlor trick than medicine."
That last statement is the most egregious misrepresentation by the Times editors. Who are these geneticists who call DNA testing a "parlor trick"? The genetic tests run by 23andMe, which use technology that is run daily at thousands of labs around the world, are nothing of the sort. They are a highly accurate assay that has been repeated millions of times and validated by hundreds of peer-reviewed studies. Usually the NY Times is one of the most thorough and accurate sources in the media, but they really dropped the ball this time.
The fact is, genetics is not fate. Identical twins, who share identical DNA, rarely die of the same causes. Thus even if you knew your genetic risks perfectly, for every mutation in your DNA, you might not find anything to change in your behavior. At most, you might learn that you should get mammograms or colonoscopies slightly more often. It's legitimate to argue that you won't learn anything useful from the 23andMe tests, but you will learn something about genetics.
As far as changing your behavior to reduce health risks, you don't need a sophisticated genetic test for that. Just eat more leafy greens.
[Note: although I'm a customer of 23andMe, I have no financial relationship with the company and I'm neither an advisor to nor an investor in them.]