Researchers Identify Genetic Link to Obesity in Mice

Human version of rare gene mutation also found in about 1 percent of obese people studied

By Robert Preidt

Thursday, July 18, 2013

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THURSDAY, July 18 (HealthDay News) -- A rare genetic mutation linked to severe obesity has been identified by researchers who conducted experiments in mice and genetic analyses of people.
The team at Boston Children's Hospital found that mice with the genetic mutation in the Mrap2 gene gained weight even though they ate the same amount of food as mice without the mutation. The gene appears to be involved in regulating metabolism and food consumption, the researchers said.
"These mice aren't burning the fat, they're somehow holding onto it," lead investigator Dr. Joseph Majzoub, chief of endocrinology at Boston Children's, said in a hospital news release. "Mice with the genetic mutation gained more weight, and we found similar mutations in a [group] of obese humans."
For the study, the researchers conducted genetic analyses of 500 people around the world. They found mutations in the human equivalent of Mrap2 (MRAP2) in four people with severe, early onset obesity. Each of the four patients had only one copy of the mutation, according to the study in the July 19 issue of the journal Science.
The finding suggests that these rare mutations might directly cause obesity in less than 1 percent of obese people. But other mutations in the MRAP2 gene may be more common and might interact with other mutations and environmental factors to cause more common forms of obesity, the study authors said.
Further investigation into how these mutations work may improve knowledge about the body's mechanisms for energy storage and use, the researchers noted in the news release.

SOURCE: Boston Children's Hospital, news release, July 18, 2013

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