When watching the Olympics games these next couple ofweeks, you might see some "super" genetic mutations in action.We all have a gene called ACTN3, but certain variants of it help our bodies make a special protein called alpha-actinin-3. This protein controls fast-twitch muscle fibers, the cells responsible for the speedy tensing and flexing of the muscles involved in sprinting or weight-lifting. Unsurprisingly, this variant that makes the protein has been associated with power athletes.This discovery happenedaround 2003,when geneticists studying elite sprinters and power athletes found that very few among them had two defective ACTN3 copies. The study was conducted on 436 Australians, of which 50 were athletes who had competed in the Olympics. Theresearchers observed that less than 3% of male and female sprinters in the study had two defective ACTN3 copies.Genetics are, of course, just one component of what could make an Olympic athlete great. So, even if you had the specific mutation, you wouldn't necessarily be a great athlete if you spent every day after work sitting on the couch. Still, the association between the genetic mutation and athletic performance is interesting.As Daniel MacArthur, one of the authors on the 2003 study that linked ACTN3 and athletic performance, put it in a 2008 Wired post:"So super-elite athletes need to have the right ACTN3combination, but they also have to have a whole host of other factors working in their favorthis one gene is just a minor ingredient in a large and complex recipe. In fact, most studies performed so far suggest that ACTN3 explains just 2-3% of the variation in muscle function in the general population. The rest of the variation is determined by a wide range of genetic and environmental factors, most of which (particularly the genetic factors) are very poorly understood."But researchers have kept investigating what all ACTN3 can tell us. In a2016study,Chinese scientists found that of the 59 elite athletes that they sequenced, none had two copies of the defective ACTN3. Interestingly, they also found that the athletes who had both copies of the active gene performed better than those with one or two copies of the defective gene.And yet another studyofsprinterscame to the conclusion that having two active copies of the gene "might be the difference between a world record and only making the final."Among the general population, however, some18% are completely deficient in the speedy-muscle-contracting protein, meaning that they inheritedtwo defective copies ofACTN3. And for that set of people, all is not lost: A 2013 study of Brazilian soccer players found that those with two defective copies had the "highest aerobic capacity."So, while the worlds most elite athletes compete in the400-meter racesand other races, its possible a "super" mutation could be playing a role in their already-super speed.SEE ALSO:8 genetic mutations that can give you 'superpowers'DON'T MISS:Scientists made an online calculator that tells you your 'fitness age,' and you can try it right nowJoin the conversation about this storyNOW WATCH: NASA just released a video of what it would be like to land on Pluto, and it's breathtaking
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