Gene Variant Linked to Obesity, Diabetes

Finding could lead to new avenues of treatment, researchers say

THURSDAY, April 12, 2007 (HealthDay News) -- British researchers have discovered a gene variant that predisposes some people to obesity and type 2 diabetes.

This variant is linked to only a small increase in weight, but it can lead to obesity in a people who are already overweight and dramatically increase the risk for developing type 2 diabetes, according to the study.

"We have identified a common variant in the FTO gene that by being associated with an increased body-mass index [BMI] results in an increased predisposition to both obesity and type 2 diabetes," said study co-author Dr. Andrew Hattersley, a professor of molecular medicine at Peninsula Medical School, in Exeter, U.K.

One sixth of the population have two copies of this variant, on average, and have three kilograms (6.6 pounds) of additional fat compared with those who don't inherit the variant, Hattersley said. "This increases the risk of obesity by approximately 67 percent and type 2 diabetes by about 40 percent," he said.

In the study, Hattersley and his colleagues examined 13 studies that included 38,759 people of all ages. The association of this gene variant to obesity was found in people 7 years old and older. The role of the FTO gene in the body is not known, the researchers noted.

This study further shows that genetic factors are as important as environmental factors in determining which people become overweight and obese, Hattersley said.

"However, it is not known if FTO alters the response to a particular lifestyle or by altering eating or exercise alters lifestyle," Hattersley said. "These findings suggests a completely novel and unexpected pathway in the regulation of obesity which might become a target for treatment of diabetes or obesity in the future."

One expert thinks that while this gene appears to be important in determining obesity, it is probably not the only gene involved.

"The authors presented very convincing results of the possible association of the FTO gene with BMI, and more particularly the fat portion of BMI," said Yvon C. Chagnon, the director of the Genomic Laboratory at Laval University Research Center, in Quebec.

It appears that this gene is very basic and important in the control of fat in humans, Chagnon said. "However, it is obvious that many other genes should be involved in the control of BMI as illustrated by the relatively low percentage of variance explained by FTO," he said.

"This gene will probably have multiple and unsuspected functions," Chagnon added. "This implies that there are numerous genes for a given complex trait such as obesity. FTO becomes a good example of this unexpected and completely new association of a gene with a biological trait."

More information

For more information on obesity, visit the U.S. National Library of Medicine.

SOURCES: Andrew Hattersley, M.D., professor of molecular medicine, Peninsula Medical School, Exeter, U.K.; Yvon C. Chagnon, Ph.D., director, Genomic Laboratory, Laval University Research Center, Quebec, Canada; April 12, 2007, Science
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