Study Finds First Genetic Link For Obesity

Researchers today announced the discovery of the first common gene link to obesity.

They reviewed genetic data on more than 38,000 children and adults in the U.K. and Europe. A certain variation in the FTO gene was associated extra body fat, obesity, and type 2 diabetes.

Other studies show there are genetic links to obesity. But "the key thing about this finding is that this is a common variant, which is present in over half the population" studied, Andrew Hattersley, D.M, FRCP, told reporters in a news conference. Hattersley is a professor of molecular medicine at Peninsula Medical School in Exeter, England.

The finding sheds new light on the genetics of obesity. But diet and
exercise still count, researcher Timothy Frayling, Ph.D., tells WebMD.
"Certainly diet and exercise are very important factors in influencing obesity risk and regardless of your genetic makeup it remains important to try to eat sensibly and exercise," says Frayling, an associate professor at Peninsula Medical School.

"However," Frayling says, "we all know people who are careful with their diets and take regular exercise but still cannot avoid putting on weight as they get older, whilst, conversely, there are people who are not very careful and remain slim.

"It is these types of differences that are likely to have a genetic component and our finding represents one of those genes," says Frayling.

The researchers noticed the FTO gene variation when they screened the genes of nearly 2,000 diabetes patients and almost 3,000 people without diabetes in the U.K.

Participants with diabetes were more likely to have a certain FTO gene
variation, which was also associated with a higher level of body fat and higher BMI (body mass index). Next, the scientists reviewed gene data from an additional 35,000 European participants in 13 studies.

One in six participants had two copies of the FTO gene variation. They had, on average, nearly 7 pounds of extra weight, compared with those with no copies of the FTO gene variation.

"This increases the risk of obesity by approximately 67 percent and type 2 diabetes by about 40 percent," says Frayling.

The FTO gene variation was linked to extra pounds in participants as young as 7 years old but didn't appear to influence fetal weight.

The study doesn't show participants' diet and exercise habits, and the
researchers don't know exactly how the FTO gene affects body fat or weight.

"We know very little about how different versions of this gene alter how much fat you have. It could influence your appetite, your tolerance to exercise, or your metabolic rate. The next steps will be to address these questions," says Frayling.

He says one topic for further study is how people with different copies of the FTO gene respond to obesity interventions such as diet and exercise routines.

All participants in the gene studies were white Europeans, so the study
doesn't show how common the FTO gene variation is in people of other ethnic backgrounds.

"The number of people we've looked at in this initial study gives us
enormous confidence to say that yes, this is a real finding and this is a finding that will be found at least throughout the European population, because our study is limited to white Europeans," Hattersley says.

By Miranda Hitti
Reviewed by Louise Chang, M.D.
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