Not Ready for Prime Time: 23andMe

Dec 09 2013 Published by under [Medicine&Pharma]

In case you spent the last few weeks on a desert island, you may have missed the love letters flowing between the FDA and 23andMe, resulting in this disclaimer that must be signed before accessing the direct-to-consumer genotyper's website:

I understand that 23andMe only sells ancestry reports and raw genetic data at this time. I understand 23andMe will not provide health-related reports. However, 23andMe may provide health-related results in the future, dependent upon FDA marketing authorization.

A number of folks have written about this state of affairs in great detail; David Dobbs, in addition to writing an excellent article for The New Yorker, has also begun archiving the work of others here. What I present here will be the tl;dr version from the perspective of a pediatric nephrologist.

So what was 23andMe?

23andMe's mission is to be the world's trusted source of personal genetic information.

Prior to this debacle, you ponied up $99, spit in a special cup, shipped it off, and then received a bunch of information, including ancestry data. You also received notification of single nucleotide polymorphisms (SNPs) that had been associated with disease states. Over time, as new associations were reported, you would receive updates. The site also generated research into some interesting associations, including a locus that may make some crazy tasteless people dislike cilantro. *

The site now provides only ancestry information in a form that your average layperson can understand. If you wish to download your raw SNP data and poke about, it's there for your use. However, I know how much fun I had doing microarray experiments, and I doubt that your average customer will want to go down this route.

See, one problem with the old approach is the statistical knowledge necessary to interpret some of these tests. An SNP may double risk (relative risk), but if the baseline risk is 0.5%, then the absolute risk is only 1 in 100. There also may be no preventative or effective therapy for many conditions.** Add to that the lack of medical guidance from a web site, and you can rapidly see where trouble could be brewing. For example, from the Dobbs' article:

Kenneth Britten, a neurobiologist and a customer, learned he has one copy of the gene that increases Alzheimer’s risk, which raises his nominal risk to about one in seven. But he then did enough reading to learn that because neither of his parents developed Alzheimer’s, he could essentially erase this extra nominal risk if he started exercising regularly before he developed symptoms. (He says he now works out a lot.) But he’s a neurobiologist in his prime. A fifty-five-year-old who is confused and depressed and learns that he carries two copies of the risk gene and stands an eighty-per-cent chance of getting Alzheimer’s might reach for a gun, which is the kind of scenario that some genetic counsellors worry about.

Even when the patient seeks out appropriate medical advice, we medical professionals may not know what to do, as discussed here by Dr. Jen Gunther:

Say you are a young woman and you get tested via 23andMe and you are told based on your genetic profile that you carry a genetic mutation that may increase your risk for blood clots. You have no personal or family history of blood clots so you had no clinical indication for testing, yet now you have these results. What next?

Certain genetic mutations do confer an increased risk of abnormal clotting, some significantly, although not everyone with the mutation that you tested positive for will have a blood clot. In fact, most won’t and so universal screening isn’t recommended. Many investigators have looked at this specific mutation and wondered, should we screen women with no history (personal or family) for this mutation? After all, women are more likely to take a medication with estrogen (birth control pills) and they get pregnant, both of which increase the risk of blood clotting, which is potentially fatal. However, after a lot of studiesobsessive reviews, and hashing it out at meetings the experts seem to agree. Mass screening, testing women with no family or personal history, for this specific mutation is likely to cause more harm than good, so we don’t recommend it.

But now you have the result and you tested positive. Now you have the result that if you act upon it might cause more harm than good. You just don’t know. What do you do? Do you go with the belief that your risk might be higher? Do you ignore the results? It’s a conundrum.

There are certainly cases where knowing the specific genotype can improve therapy, particularly in pharmacogenomics. For the most part, the current state of affairs does not warrant mass screening of SNPs for personal health. If all we can do is tell you to live a healthy lifestyle, do you really need to spend an extra $99?

*Cilantro may be the most wonderful herb on this planet, and my spouse hates it. Yes, I consider him crazy for this trait.

**Many or most disorders benefit from physical activity and a healthy diet to maintain a normal body weight. The same advice we doctors give pretty much everyone. And how many follow it?

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