Controversial test to 'determine sporting fate' is released in US market

A simple genetic screen will help you decide which sport your child is most suited to. That is the claim made by Atlas Sports Genetics (ASG), of Colorado, US, in the launch last week of their new genetic test. Although previously marketed in several other countries, this is the first time the test has been available in the US. Like the earlier versions, the decision to profit from such genetic analysis has attracted wide ranging opinion.

For the price of 149 US dollars, Atlas will profile a child's DNA - via a cheek swab - in order to characterise the variants of the ACTN3 gene they carry. ACTN3 codes for alpha-actinin-3, a protein component of fast-twitch skeletal muscles. These enable rapid, forceful movement, as compared to slow twitch muscle. There exist two variants of the gene; labelled R and X. R variants produce a functional protein, whilst X variants do not. According to the website atlasgene.com, two R variants predispose a child to be a sprinter or weight lifter. Two X variants and the child will be better in endurance running or cross-country skiing.

Kevin Reilly, president of ASG, told the New York Times that 'if you wait until high school or college to find out if you have a good athlete on your hands, by then it will be too late. We need to identify these kids from one and up, so we can give the parents some guidelines on where to go from there'.

ACTN3 became popular when a 2003 paper in the American Journal of Human Genetics reported a relationship between alpha-actinin-3 and human elite athletic performance. The study looked at 429 elite white athletes, including 50 Olympians, and found that half of 107 sprinters had two copies of the R variant. More convincingly, just five per cent of sprinters carried two copies of version X, compared to 18 per cent of the general population and 24 per cent of the endurance runners.

But the validity of applying (albeit) proven correlations to a complicated trait like athleticism is looked upon unfavourably by many, not least Daniel MacArthur, co-author of the 2003 paper. Writing on the website scienceblogs.com, MacArthur warns that 'ACTN3 explains just 2-3 per cent 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'.

To date, over 200 catalogued genes have been purported to influence athletic ability. In 2007, mice genetically engineered to over-express a glucose metabolising gene, called PEPCK, were found to be leaner, healthier and able to run at high speeds for extraordinary time lengths before resting.