Tomorrow's sports stars: Is talent all in the genes?

Some people are born to play football. So says David Beckham's official website. After attending the Bobby Charlton Soccer School at 11, Beckham was selected to be a trainee for Manchester United at just 16 years old. The rest, as we know, is history, tattoos and Gillette razor blades. But what if footballers really are born and not made? A test to determine whether a child will turn into an élite soccer player is the stuff of football managers' dreams.

Recently, a European club approached Dr Henning Wackerhage, from the Institute of Medical Science at the University of Aberdeen, to ask if he could genetically screen for potential football stars. It's not as fanciful as it sounds – there is already a "Sports Performance" gene test available over the counter from a company that normally specialises in paternity testing, Genetic Technologies, based in Victoria, Australia.

Genetic Technologies' gene test, which, the company says, will "allow you to realise your full potential", is based on research carried out in 2003 by a group of Australian scientists. Yet it turns out that not only are these scientists not involved in this genetic testing, they have little faith in the screening process itself. One of the key authors, Dr Daniel MacArthur, from the Institute for Neuromuscular Research at The Children's Hospital in Westmead, Sydney, says: "It's safe to say it's premature to use this test to predict performance, particularly in soccer athletics. And really there is no point in the rest of us having the test. The gene the company is looking for is unlikely to influence anyone who is only interested in sport at an amateur level." So what is the real truth behind the search for "soccer genes"? Will we one day be able to determine that a star has been born? Is it so ridiculous to wonder if there is something in the DNA of, for instance, Frank Lampard, the former West Ham player and father of the current Chelsea star? After all, Frank Junior is also the cousin of former England midfielder Jamie Redknapp.

The story begins on another pitch. MacArthur's co-author, Professor Kathryn North, also based at Westmead, was studying people with neuromuscular disease in the hope of finding a cause if not a cure. North focused on a gene called ACTN3, which is found in a wide variety of organisms, from slime moulds to chickens as well as humans. ACTN3 controls the production of protein in muscles so seemed an excellent candidate. To the scientists' joy they discovered that the patients were deficient in the protein, alpha-actinin-3, produced by the ACTN3 gene. "But," North says, "our elation quickly turned to confusion." It transpired that healthy relatives of the patients lacked this protein too – as did several members of the research team. In fact, later research was to show that almost a fifth of white Caucasians are deficient in alpha-actinin-3. This protein is found in fast-twitch muscles, the type that are predominantly used to make powerful movements, such as sprinting and jumping, yet a fifth of the population are not crawling around unable to run for the bus.

Everyone has two copies of ACTN3 but some people have a variation which is known as R577X. This variant stops muscle cells from reading the entire code of ACTN3. Therefore, if a person has two copies of R577X, it means they cannot produce the protein alpha-actinin-3 at all. Yet since 18 per cent of the population don't make this protein, it means the story must be more complex. In fact, a second gene called ACTN2 helps compensate for the deficiency. The researchers reasoned that if there's a variation in the human population, people who have working copies of ACTN3 might be better at sprinting and power sports than the rest of us.

In short, the team had begun to unravel a complex map of genetic codes that affect our athletic abilities. In collaboration with the Australian Institute of Sport, they took DNA from more than 400 élite athletes who competed in a wide range of sports from swimming to cross-country skiing and compared their DNA with approximately the same number of "normal" people. What North found was that the endurance athletes generally had a deficient version of both genes. In other words, they discovered that lacking functioning copies of ACTN3 actually benefits slow, efficient muscle performance. In contrast, power and sprint athletes had two fully functioning copies of ACTN3. Thus, ACTN3 became dubbed the "speed gene".

In theory, this means that it would be possible to screen for copies of ACTN3, but would this really be a good test to find the next football legend? MacArthur says: "The important issue is to remember that the ACTN3 gene only accounts for 2 to 3 per cent of the variation in muscle strength and sprinting performance in non-athletes. This means that ACTN3 is not something that most of us would ever benefit from being tested for. However, this 2 to 3 per cent can make a big difference for super-élite athletes. In addition to high motivation and world-class training, these rare individuals need to have a near-perfect set of genes to have a chance of winning an Olympic medal. At this élite level, the ACTN3 gene appears to have a particularly strong effect on sprinters – sprinters need to have at least one 'sprint' version of ACTN3 to have a chance of competing at an Olympic level." So a test that shows that you do not have the speed gene would indicate that you could never become an Olympic sprinter no matter how hard you train. But if you do have speedy genes, does that mean you are more likely to one day be lifting the silverware instead of merely watching from the sidelines?

Some research seems to back this up. Just published in the British Journal of Sports Medicine is an article by Professor Alejandro Lucia, from the European University of Madrid, which shows that élite soccer players tend to have these genes for speed. Yet Lucia is vehemently opposed to testing children and says with a shrug, "Why bother? The genes we were born with are those we must live and die with." He also adds that you can be an élite sportsman without the speed gene, citing the example of a Spanish Olympic-class long-jumper whose DNA he tested. The athlete won a gold medal and is also an élite sprinter yet, in spite of the fact that ACTN3 is responsible for "generating forceful muscle contractions at high velocity", this young man does not have any functioning copies of the gene.

Wackerhage says, "The ACTN3 test is wholly inappropriate for footballers. It's like looking at a Formula One car that has a small engine. You know it won't be very quick. But there's so much more to a Formula One car than the engine – it relies on its world-class tyres, carbon shell and steering – just as a world-class football player needs a suite of skills to stay calm under pressure, have precise motor coordination and be a good endurance player as well as a fast sprinter."

The test offered by Genetics Technologies costs around AS$100 (£47) and involves taking a saliva sample with a mouth swab. Clients receive their results within 10 to 15 days. MacArthur says that a more sophisticated version of the test will be available in the future, but we can't predict when: "ACTN3 is one of possibly hundreds of different genes that can affect athletic ability. We know of only a handful of these genes at the moment, and it will take much more research before we can find all of them and determine their precise effects on athletic potential."

Before we go down this route, Wackerhage says we should consider the ethical implications of genetic screening. A gene that would make you a super-cyclist could later give rise to cancerous cells. It might well be possible to eliminate athletes at an early stage on the basis that they could never run fast or far enough – even though such a test may not be 100 per cent accurate and cannot account for an athlete's mental strength. Conversely, athletes could be discriminated against on the grounds of future injury; for instance, a boxer should not compete because he has the variant of the gene APOE that would predispose him to brain damage.

Even if we do jump through these ethical hoops, will the beautiful game ever turn to science to find the next set of Ronaldos and Beckhams? Huw Jennings, youth development manager at the FA Premier League, thinks such testing is not yet capable of plucking a future Ryan Giggs out of the nursery: "While you may be able to identify athletic ability, the road from promising youngster to top professional is far from smooth, and it doesn't necessarily follow that talented athletes will become talented footballers." Yet we know that genes influence approximately 50 per cent of sporting prowess, from oxygen uptake to maximum running speed.

In the future, Wackerhage says, "There will undoubtedly come a time when it will be scientifically possible to test for sporting aptitude but we have to decide whether we are happy with such tests and the conclusions we base on them."

The making of a champion

Power
Myostatin is the growth factor that acts as a brake on muscle development; a person with a high level of myostatin will have less well developed muscles. A mutation in the gene for myostatin expression will remove this brake, and could lead to rapid muscle growth. A German toddler already has twice the muscle density of his peers – useful if he becomes a bodybuilder.

Height
Insulin-like growth factor 1 (IGF-1) is the hormone most responsible for regulating cell growth and development. An athlete with abundant IGF-1 and other growth hormones and regulators will be tall; useful for basketball players.

Speed
Super-mice have been genetically engineered to run faster and further. They over-express a gene for the enzyme phosphoenolypyruvate carboxykinases (PEPCK-C), which is modified so that it is only active in skeletal muscles. The mice produce less lactic acid and burn more fat. They can run at 20 metres a minute on a treadmill for up to six hours.

Fitness
Erythropoietin (EPO) is a hormone that regulates the numbers of red blood cells. Altering the EPO receptor enables blood cells to carry higher levels of oxygen, which can result in greater cardiovascular stamina. The effect is similar to that of blood doping, an illegal practice.

Acceleration
The gene ACTN3 – the "speed gene", for fast-twitch muscle – makes muscles contract quickly. It's crucial for sprinters and sports requiring short, powerful movements. A variant (R577X) is needed for the slow, efficient muscle contractions required by endurance athletes.

Endurance
A variant of the bradykinin beta 2 receptor gene (BDKBR2) has recently been linked to the ability to run long distances in Olympic standard athletes. It is thought to work by causing skeletal muscles to contract efficiently.

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