Scientists Find Gene That Makes You Fat

More than half of the population carries a gene that makes people more likely to pile on the pounds, scientists announce today. They hope the discovery could eventually lead to treatments to help people lose excess weight they carry simply because of their genetic make-up.

Obesity is associated with an increased risk of type 2 diabetes, heart disease and other medical problems and is rising in prevalence in most western countries, where at least 20 per cent of the population is clinically obese.

The work – conducted over 15 years – indicates that some people are programmed to put on weight.

New hope of treatments to bolster diet and exercise have emerged in recent years with the discovery of an “alphabet soup” of genes that influence obesity, from the way fat cells develop to the mechanisms that make us hungry.

Today’s announcement, in the journal Science by teams in Oxford and Exeter, is significant.

Unlike previous work, it shows a very common genetic link with mild obesity rather than a rare genetic link with extreme obesity.

The team of 42 scientists found that if people carry one copy of a variant in a gene called FTO, as does half of the general population, it will lead to a gain in weight of 2.6lb or put just over half an inch on their waists and raise their risk of being obese by one third. If people have two copies of this variant in the FTO gene, which is the case in one in six of the population, then they will gain almost 7lb more than those who lack the variation and are at a 70 per cent higher risk of obesity.

In the future, once scientists have found additional obesity genes, it may be possible to offer advice based on a person’s genetic make-up.

When scientists understand more about the function of this first obesity susceptibility gene, they will be able to help people to lose weight more effectively despite their genes.

This may be achieved with drugs targeted at the molecular pathways the gene influences.
     
“We are eating more but doing less exercise, and so the average weight is increasing, but within the population some people seem to put on more weight,” said Prof Andrew Hattersley from the Peninsula Medical School. He led the work with Prof Mark McCarthy from Oxford University.

“Our findings suggest a possible answer to someone who might ask, ‘I eat the same and do as much exercise as my friend next door, so why am I fatter?’.”

Prof Hattersley added: “Our study is as close as you can get to definitive as we have tested over 42,000 people in the first paper and found association with body mass index at every age [from seven to 70] and in populations throughout the UK and Europe.

“So this is the first common variant described that consistently is associated with diabetes and obesity.

“The second important finding is that this has identified a potential new molecular pathway for obesity and hopefully it may lead to new biology and even new treatment.”

The team first identified a link to obesity through a study of 2,000 people with type 2 diabetes and 3,000 controls. This was part of the Wellcome Trust Case Control Consortium, one of the biggest projects to identify the genetic variations linked with major diseases.

The team used a sophisticated “gene chip” to look for differences across the whole genetic code and found people with type 2 diabetes were much more likely to have this FTO variant.

The researchers then tested a further 37,000 people from Bristol, Dundee and Exeter as well as a number of other regions in Britain, Italy and Finland. In every case the same variant in the FTO gene – which is mostly present in the brain and pancreas, among other key tissues – was associated with type 2 diabetes and obesity.

They also showed that in children, this particular FTO variant was associated with increased body weight.

Members of the research team still do not know why people with copies of this variant are more at risk of obesity, though it is thought that it may play a role in cellular energy.

“We welcome this result, which holds promise for tackling rising levels of obesity and the associated risk of developing type 2 diabetes,” said Professor Simon Howell, the chairman of Diabetes UK.

According to the 2001 Health Survey for England, more than a fifth of males and a similar proportion of females aged 16 and over were classified as obese.

Half of men and a third of women were classified as overweight.