the Athlete Gene

Jacob P. Koshy

font size
Email Print

New Delhi: North Indian athletes are as likely to be world-class sprinters as, say, white Europeans, if it were just a matter of genes, according to a duo of geneticists at the Sanjay Gandhi Postgraduate Institute of Medical Sciences in Lucknow.

Their research adds to studies focusing on the “athlete gene”, which in the last decade and a half has gripped international research in sports medicine.

Though scientists say that more than 92 genes play important roles in determining what makes an Olympic-level sportsman, the athlete gene is a region of DNA that, supposedly determines whether certain individuals are predisposed to be better athletes.

Secret of power: The reason why everyone can’t run the 100m in less than 10 seconds is because a mutation in the ‘athlete gene’, or ACTN3, overwrites the effect of the gene in most people.

Much like a bowling ball knocks down pins, the athlete, or alpha actinin-3 (ACTN3) gene triggers the production of alpha actinin, a protein that boosts a certain class of muscle fibre, called fast twitch type-2 muscle fibre, which helps muscles generate extra force when they are in motion.

Though this gene is present in more than 60% of the population, the reason why everyone can’t run the 100m in less than 10 seconds is because a mutation in the gene over-writes the effect of this ACTN3 in most people.

Those with working ACTN3 have a further caveat—the type of ACTN3. All identified human genes come in pairs, and in case of ACTN3, there are ‘R’ and ‘X’ variants. Therefore, every human inherits a copy of each gene from both parents throwing open three possibilities: an RR, RX, or XX. Predictably, most people are RX.
Kathryn North, an Australian researcher, and her colleagues caused a flutter in the world of sports medicine in 2003 when she published, in the peer-reviewed Bioessays, a research that said most of the sprinters, weightlifters, sports that required bursts of power (94%) had an R variant, with 50% of them having an RR.

The athletes who weren’t into power sports were markedly low on RR, over 60%. Having two of the same variants, RR or XX, doesn’t mean you have will have increased expression of RR or XX, but a higher probability that you will be backed up in case of a mutation.

That’s like saying having two operating systems on your computer hard drive doesn’t imply double the system’s performance, but only increases your chances of having a working computer in case of a virus attack.

Further tests by researchers found that only 13% African American and 1% of African Bantu (West African), well recognized for their athletic prowess, lacked at least one ‘R’, with a double RR present in at least 60% and 80% of their respective populations.

“Just to find out the Indian scenario, we decided to have such a test for an Indian population,” said Balraj Mittal, one of researchers.

They sampled 125 blood donors in Lucknow and a report in this week’s issue of Current Science, a peer-reviewed journal published by the Indian Academy of Sciences, that 52% of them had at least a single ‘R’, close to the average Asian population of 50% and 56% of European whites.

ACTN3 triggers the production of alpha actinin, a protein that boosts a certain class of muscle fibre

The scientists say they want to downplay the role of genes in determining athletic abilities. “If you compare Olympic medal tallies,” Mittal said, “there’s no comparing Indians with the Europeans, Americans or the Chinese.”

Thus, training, grooming and psychological motivations were the most important factors, he added.

A slew of companies such as the US-based 23&Me Inc. and Australian Genetic Technologies Ltd, among their bouquet of genetic testing services offer to check for ACTN3, according to information on their websites. Emails to all of them were not returned.

“Though genetic tests are being promoted by these companies for choosing an appropriate sport career, the presence of this gene in no way guarantees elite athletic ability,” noted Balraj. “Nutrition and socio-economic conditions play a major role,” he added.

However, Bharat Inder Singh, an expert on sports medicine at the Fortis group of hospitals, is emphatic that “genetic testing” is the future of athletics.

At international competitive levels, there isn’t a huge difference among athletes, and even if a gene can make an incremental difference, it’s potential is bound to be exploited.”