Obesity in the Genes?

Common Variation in FTO Gene May Make Obesity More Likely

Reviewed by Louise Chang, MD on April 12, 2007
From the WebMD Archives

April 12, 2007 -- 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, DM, FRCP, told reporters in a news conference.

Hattersley is a professor of molecular medicine at Peninsula Medical School in Exeter, England.

Lifestyle Still Counts

The finding sheds new light on the genetics of obesity. But diet and exercise still count, notes researcher Timothy Frayling, PhD, 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.

Obesity Gene Study

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% and type 2 diabetes by about 40%," 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.

Diet, Exercise Habits Unknown

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.

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Show Sources

SOURCES: Frayling, T. Science Express, April 12, 2007; online edition. Andrew Hattersley, DM, FRCP, Peninsula Medical School, Exeter, England. Timothy Frayling, PhD, associate professor, Peninsula Medical School, Exeter, England. News release, Wellcome Trust.

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