Test your kids' genes for sports ability: hype or reality?

A company called Sports X Factor recently announced that it's selling a genetic test that will reveal your potential to be a sports star. They're marketing it as a way to predict what sports your kid will excel at. Is this real, or just another over-hyped attempt to cash in on parents' aspirations for their children?

Sports X Factor, which sells the test for $180, stated in a press release a few weeks ago that the test
"can make workouts more effective, children’s sports choices more appropriate and trainers’ awareness of potential risk factors more precise. It can even save a life."
Wow, sounds impressive. But is it true?

In some ways, this is nothing new. Another company, Atlas Sports Genetics, started offering a similar test in 2008. They make similar promises, claiming that their test
"Gives parents and coaches early information on their child’s genetic predisposition for success in team or individual speed/power or endurance sports."
Unlike some of the rank pseudoscience I often blog about, this claim actually has some real science behind it. Back in 2003, Kathryn North and colleagues at the University of Sydney published a paper in a leading genetics journal about a gene called ACTN3. They found that mutations in this gene were associated with elite sprinters, both male and female. Superficially, it's easy to take this association and turn it into a "speed gene," but it's not.

The science is much more nuanced. (Isn't it annoying when things aren't so simple?) ACTN3, which affects muscle fibers, has three common genotypes. Let's call them Red, White, and Blue.* Elite-level sprinters are usually Red or White: 92% of male sprinters and 100% of female sprinters in the original study were one of these. In the general population, 30% of people are Red and 52% are White. For elite endurance athletes, there tendency is the opposite: slightly more of them are Blue, but the difference isn't significant.

The advice from Atlas Sports Genetics is a gross over-generalization of the science. Here's how they interpret the test results:
Blue: Predisposition to endurance events
White: Equally suited for both endurance and sprint/power events
Red: Predisposition to sprint/power events
The science simply isn't this clear. The only thing you might say is that Blue genotypes are not likely to be Olympic sprinters. But that's true of 99.999% of us anyway. There's no "predisposition" to particular sports.

The newer test from Sports X Factor looks at 9 genes, not just ACTN3. Although a broader test might sound superior, the genes they test include ApoE4, which is associated with a slightly higher risk of Alzheimer's disease. This raises serious ethical questions. Do you really want your child to know that he/she might be pre-disposed to Alzheimer's? As Hank Greely, a Stanford lawyer and bioethicist, said in the Washington Post, “I think this company is a good advertisement for the need for more regulation of genomic testing,”

I suggest that parents save their money, and instead take a test that I'm offering right here, for free, to determine your child's sports potential. Just follow these two easy steps:
  1. Ask your child, "do you want to play soccer?"
  2. If the answer is yes, sign your child up for a kids' soccer team.
Wasn't that easy? And it works for almost any sport! Just replace "soccer" by your kid's favorite sport. Oh, and then you have to go to the games. That's the hard part.

*For science geeks only: the genotypes Red, White and Blue are RR, RX, and XX respectively. The mutation is R577X, where the X is mutation that introduces a premature stop codon at position 577 that shortens the ACTN3 protein. RR means that both copies of the protein are full-length. RX means one copy is shortened, and XX means both are. About 18% of the population is XX ("Blue").

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