Common gene causes obesity, says study

Common gene causes obesity, says study
By Clive Cookson in London
Copyright The Financial Times Limited 2007
Published: April 13 2007 03:00 | Last updated: April 13 2007 03:00


The first clear-cut evidence of a common gene that explains why some people get fat and others stay lean is published today. A British study of 38,000 people shows one-sixth of the population carries a 70 per cent higher risk of being obese as a result of variants in the so-called FTO gene.

"Even though we have yet to understand the role played by the FTO gene in obesity, our findings are a source of great excitement," said Mark McCarthy of Oxford University, one of the study leaders. "By identifying this genetic link, it should be possible to improve our understanding of why some people are more obese, with all the associated implications such as increased risk of diabetes and heart disease."

Although other genetic links to obesity had been identified, these caused severe obesity in extremely rare cases - typically one person in 10,000 - said Andrew Hattersley of Peninsular Medical School, Exeter. FTO mutations, in contrast, were very common.

About half the population carries one copy of the FTO variant, which leads on average to a weight gain of 1.2kg compared with those without the variant. People who carry two copies - one inherited from each parent - will gain 3kg.

FTO is one of many human genes whose biological role is still a mystery. It produced a protein unlike any other known to science, said Prof McCarthy, though there might be a clue in the fact FTO was very active in the hypothalamus, the part of the brain involved in appetite and satiety.

Today's online publication of the study by the journal Science is likely to trigger a large international research effort to understand what FTO does. Scientists hope it will lead to a biological understanding of the reasons why some people put on weight and others do not under the same conditions - and the pharmaceutical industry will be looking for leads to potential drugs.

Prof McCarthy said the researchers and their main funding body, the Wellcome Trust, "thought long and hard" about patentingthe discovery and decided not to. The immediate reason was scientific competition: they knew other researchers were on the track of FTO and did not want to risk delaying publication while they were tied up in the intellectual property debate.

Independent scientists hailed the study as a landmark in understanding obesity although some were concerned about the psychological impact on the public health campaign against the "obesity epidemic" that is sweeping the industrialised world and spreading to developing countries.

There was a risk of people reacting to news of a "gene for obesity" in a fatalistic way, Prof McCarthy conceded, and imagining wrongly that fatness was determined by their DNA.

But Susan Jebb, head of the Medical Research Council's Human Nutrition unit in Cambridge, hopes it will have the opposite effect.

"People who know they are carriers may be more motivated to adopt a prudent diet and healthy lifestyle to decrease their risk," she said.