Single gene may keep you from burning calories

London, February 23: A gene can make you fat, said German researchers on Sunday. The discovery of the culprit gene has ignited new hope for obesity-fighting drugs.

After carrying out a study on mice, German investigators found a particular form of an obesity-linked gene – the FTO gene, which causes building-up of fat in the body. Mice that carried the gene were fatter than those who did not, even though both groups were given the same amount of food and made to exercise equally.

Mice lacking the FTO gene displayed retarded growth after birth and were found to have a smaller amount of fat tissue. By the age of 6 weeks, these mice had 30 percent to 40 percent less weight than their "normal" counterparts.

The connection between FTO gene and obesity had been long suspected but there was no theory to explain it. It was believed that the gene causes weight-gain by influencing appetite and food intake.

But this time the German team, led by Ulrich Ruther of the University of Dusseldorf, went a step further to find out the actual effect of the gene.

The FTO gene probably affects the rate of the metabolism. The research, published in the Feb. 22 issue of the journal Nature, suggested that fat-burning in mice without the FTO was way faster than in animals with a functioning gene.

"These animals are eating as much as the control animals but burning calories through a non-exercise mediated pathway," said one expert, Dr. Stuart Weiss, a clinical assistant professor of medicine at New York University School of Medicine in New York City.

The gene possibly keeps a tight rein on the amount of energy given off in the form of heat.

Although FTO gene was long suspected to be associated with obesity in humans, “until now, it was not clear whether this genetic variation was likely to influence obesity by altering the expression or function of the FTO gene itself or some neighboring gene,” said Professor Stephen O'Rahilly, a metabolism expert from Cambridge University, who was not involved in the study.

“This work provides a crucial piece of evidence supporting the notion that the FTO gene itself is likely to be involved in the effects of common human genetic variants on body fat,” he said.

With obesity being the biggest threat to human health today, the recent findings might help in research and development of drugs that target the offender gene and modify its action.