Details are pretty sketchy, but a press release announced today suggests that personal genomics company 23andMe has performed a genome-wide association study comparing 100 current or former professional NFL players with a set of controls of unspecified sample size.
The shocking result:
The study did not find the tested players to be genetic outliers, suggesting that genetics may not be a good predictor of athletic success.
It’s unsurprising that the results of this study are negative (more on this below), but the conclusions they draw from this are fallacious. In fact we know from twin and family studies that many (but not all) traits related to athletic performance are highly heritable; researchers just haven’t been able to track down the vast majority of the genetic variants responsible yet, and this study is no exception.
What 23andMe have actually shown here is that the limited subset of genetic variation captured by their genotyping chip (which almost exclusively targets genetic variants with a frequency of greater than 5%) doesn’t include any variants with an extremely strong association with NFL prowess
That shouldn’t come as a surprise to anyone who’s been following advances in human genetics for the last few years; a genome-wide association study on a highly complex trait with a sample size of 100 has, historically speaking, a vanishingly small chance of yielding any positive results at all. (Yes, there are exceptions, but I don’t think a sensible prior expectation would be that athletic performance has a similar genetic architecture to macular degeneration.)
The press release argues that the results “speak to the breadth of the genetic research the company is undertaking”. That may be so, but I certainly hope they aren’t indicative of the general quality of 23andMe’s research program. Much as I hate to say it about a company whose work I generally admire, this study carries all the hallmarks of being pure PR fluff. If you want to do a GWAS for athletic performance, at least wait until you have a homogeneous sample that’s well-powered enough to have a fighting chance of detecting real associations.
On the bright side, 23andMe has been building up much more sensible sample sizes for other projects, including 4,500 older amateur athletes
and over 3,000 Parkinson’s disease patients
. I’m hopeful that we’ll see something a little more interesting than this NFL story roll out of the company over the next few months.