Thursday, May 16, 2013

On 23andMe

We've been thinking about SNPs in the lab lately, and it made me sort of curious about my own genotype. I'd been contemplating ordering a kit from 23andMe, a company which analyzes your spit-derived DNA on a SNP array. The recent price-drop to $99 made the decision pretty easy. So, now that I have my results, were the $99 well spent?

Let me start by saying that, despite 23andMe's marketing ("take a more active role in managing your health" ), I was under no illusion that I would learn anything too useful about my health. After all, most of the SNPs associated with (non-Mendelian) traits explain very little of the actual variation in the population. For example, the "Height" SNPs on 23andMe only account for, like, 0.6 inches of human height variation. It was cool, though, to learn that I'm not a carrier for any of the 50 or so Mendelian diseases (ex: Cystic Fibrosis, Phenylketonuria) listed on the website.

The most surprising thing I saw was that, according to my genes, I should almost certainly be lactose intolerant---which I know I’m not. The website has a neat "community" feature for each SNP, where people can discuss whether they actually have the associated phenotype (the page for the "intelligence" SNP is pretty funny…with lots of people defensively posting their IQ scores).  On the page for lactose intolerance, I saw tons of people post something along the lines of “Yup, but I was fine until my late 20s!” So, at the very least, I’ve learned that I should binge on ice cream and cheese while I still can...

Part of the problem with interpreting the “usefulness” of health results from 23andMe is that there’s so much random stuff that there’s sort of a dilution effect for what I can get worried about. For example, if I had only learned that I have a 34% increased risk of developing prostate cancer (the average probability is 17.8%, and my SNPs supposedly push me up to a 23.9% risk), I might be a bit shaken up. But I’m also twice as likely than average to get exfoliation glaucoma and 35% more likely to get atrial fibrillation. And then I’ve got to balance my worry with the relief that I’m 25% less likely to get venous thromboembolism, and I have a 12% decreased risk of getting gallstones. I calculated that, umm, I should be approximately 0.43522% more worried about my health now than I was before I saw my results. 

I guess I was most excited to learn about my ancestry. The website maps certain SNPs to geographic locations 500 years ago, when rapid migration did not yet exist (nice explanation of how they estimate ancestry)I knew, generally, that my ancestors were from Gujarat, India---a central, coastal state separated from the Arabian peninsula and the Horn of Africa by a few hundred miles of sea. This area was highly accessible by the European colonialist explorers of the mid-20th century, and it's not too far south of the Silk Road, the ancient trading route that linked the Far East with the Middle East. The point of the contrived geography lesson is that it convinced me that I had to have recent ancestors from beyond the Indian subcontinent. In addition, I recalled that my grandfather thought he had an English grandfather, though it was a murky claim because the alleged Brit died very young, and none of our living relatives could corroborate it confidently. Anyway, this was all was thoroughly debunked by my SNP data.

So I'm more Indian than a plate of Chicken Vindaloo (which is actually sort of Portuguese).

Whether or not "personalized medicine" takes off in the near future, there's a thrill to being an early adopter, so I certainly don't regret my purchase. But I'm not sure I'd recommend it to people who are on the fence, because, chances are you won't really learn all that much.

1 comment:

  1. Haha, who would have thought Yaanik is Indian? :)

    Still, I think it's cool. Who knows. With more and more data coming in, perhaps we can strengthen the disease associations to the point where we can act preemptively.

    What I've always found interesting is that even twins can have a lot of brain plasticity. Sure, many traits show a strong genetic *component*, but there is still a lot of variation in personality and aptitude. So there's still hope for my kids... :)