The "fat gene" discovered in mice may help human weight control

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March 11, 1999
Web posted at: 6:57 p.m. EST (2357 GMT)

BOSTON (CNN) -- The so-called "fat gene" discovered in mice by researchers in Cambridge, Massachusetts may have a greater chance of leading to a human weight control drug than several other genes known to be related to obesity.

Millennium Pharmaceutical Inc. reported finding and cloning the "Mahogany" or mg gene in Thursday's issue of the scientific journal, Nature. Tests with brown mice showed a mutated MG gene allowed the animals to stay thin, despite being fed a high fat diet. Mice with the normal mg gene gained weight as they ate more fat.

And the receptive structure of the mg gene may allow researchers to target it with drugs said Dr. Karen Moore, of Millennium Pharmaceutical Inc.

"What's really good from a drug therapy point of view about the mahogany gene is that it is a receptor, a molecule that fits partly inside and partly outside the cell," she said. "It acts as a transmitter of signals. Because it's partly outside the cell it would be amenable to drug intervention," Moore added.

The mg gene is one of the first to suppress diet-induced obesity. Five other gene mutations have been linked to genetic obesity.

"All those other genes when disrupted or mutated cause obesity. This one is the other way around. We know that when it is mutated or the gene isn't there we get the desired effect, suppression of obesity," Moore said.

Still years away: a genetic diet drug

Because mice and humans have similar metabolic systems, the mg gene could be a useful target for drugs to treat human obesity. But Moore told CNN those drugs could take as much as ten years to develop.

"We know that humans have the mahogany gene, but we haven't done the appropriate biological assays (tests) to find out yet if it will act the same way. I fully anticipate that it will," she added.

With an estimated 54 percent of adults overweight or obese in the United States, any weight control discovery makes headlines. But those in the business of helping people control their weight are taking a wait-and-see attitude about the mg gene.

Dr. Lee Kaplan, of MGH Weight Control, told CNN the discovery doesn't change what overweight people should do in the near term.

"They should exercise more, stay fit, try to lose weight if it's causing medical problems . . of course while doing this, if they have a sense something new is being developed to benefit you, it's a little more enthusiasm," he said.

Obesity researcher James Hill of the University of Colorado was less hopeful about the practical benefits of the mg gene. "I'm pessimistic that we'll ever get that pill that allows us to remain sedentary, eat high-fat diets and stay lean," he said. "But that's what Americans want," he added.

The Millennium Pharmaceutical report is one of two papers on the mg gene published in the latest issue of Nature. Gregory Barsh and scientists at Stanford University School of Medicine in California reported similar findings.

Correspondent Denise Dillon and Reuters contributed to this report.

Nature: International Weekly Journal of Science
Millennium Pharmaceuticals Inc.

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