Remember the film? Editor Cyrus Farivar decided to get tested at both 23andme and a much more expensive outfit, due to heightened risk of Alzheimer. His article provides a wealth of information about how such tests work, but he concludes,
What I learned from the process, in short, is that they’re not quite ready for prime time. It may be helpful to know about a slightly elevated risk for one disease or another, but the genetics behind the results—for average consumers at least, perhaps not those purchasing full genome sequencing—is still lagging. I wouldn’t have paid my own money for these tests. (Ars covered the 23AndMe fees, Gentle offered up its trial as Science Editor John Timmer has previously worked with the company’s CEO.)
The current scientific limits are why the FDA forced 23andMe to pull their health risks section from their site for new customers. It’s why Gentle backtracked on my Alzheimer’s risk factor during a follow-up call. Today’s DTC genetic testing distills complex biology—like the presence of a certain SNP—into a fixed, digestible number. I can understand what a 12.6 percent risk for Alzheimer’s (according to 23andMe) might mean. But the fact that there are so many contributing factors both known and unknown is complicated at best and deceptive at worst.
“If you try to give someone a risk figure, you’re really not giving them an accurate risk picture,” Laura Hercher, a genetics counselor and faculty member at Sarah Lawrence College, told me. “What they should say is that the part of your risk explained by this one thing we’re looking for goes up two percent, but we don’t really know what your global risk is. It would be like if you had a stock portfolio, [and your financial advisor] looked at two or three stocks and said: these are up, and so your [overall performance] is up. The advisor wouldn’t be lying but would be very misleading.”
Remember that scene from GATTACA where the delivery room nurse reads off information that shows that our hero will die young of heart issues?
What you wanna bet the biggest factor in all types of senile dementia (most Alzheimer sufferers are old) will turn out to be just your chances of living to an advanced age? We tend to assume that northern Europeans are more at risk, and no doubt genetics support this. But northern Europeans were also among the first groups to benefit from medical advances that caused a much greater proportion of the population to “qualify for” late life illnesses. Let’s see what happens if lifespans lengthen in other parts of the world.
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