Roanoke Times
Copyright (c) 1995, Landmark Communications, Inc.
DATE: THURSDAY, August 10, 1995 TAG: 9508100069
SECTION: NATIONAL/INTERNATIONAL PAGE: A1 EDITION: METRO
SOURCE: THE BALTIMORE SUN
DATELINE: BALTIMORE LENGTH: Medium
In an article in today's New England Journal of Medicine, the researchers report that the mutation appears to speed the development of diabetes and encourage the kind of midriff bulge that raises the risk of heart disease.
Only some people who carry the defective gene are obese, defined as being more than 20 percent heftier than a person's ideal weight. And scientists said the discovery does not mean that people with the mutation can't fight fat with diet and exercise.
But overweight people with the mutation tended to carry more excess pounds and have more trouble burning fat. Those who carry the gene and suffer from diabetes tended to get sick at an earlier age.
``It does not necessarily predispose people to obesity and diabetes, but to accelerate the process of both,'' said Dr. Jeremy D. Walston, 34, a geriatrician at Hopkins Bayview Medical Center in Baltimore and the article's lead author.
``Now we can identify people, even in early childhood, who have the mutation, who are more susceptible to getting obese and diabetic,'' said Dr. Alan R. Shuldiner of Hopkins Bayview Medical Center, another author of the Journal article. ``We can recommend that they maintain near normal body weight by watching what they eat and exercising.''
Dr. Bradford B. Lowell, an endocrinologist at Harvard Medical School who was not involved in the study, noted that researchers demonstrated a weak link between carrying the defective gene and obesity.
But that's to be expected, he said, because it's likely that obesity is encouraged by a whole cluster of weak mutations working together, rather than one very powerful mutation.
As many as 30 genes, geneticists say, may play some role in how fat or thin people are.
More research will be needed to confirm that the mutation found by the Hopkins scientists contributes to obesity, Lowell said, ``but it sure looks like it will be true.'
The Hopkins scientists say the mutation is carried by about one out of eight white Americans, one out of four black Americans and Mexican Americans, and one half of a group of American Indians studied - the Pima Indian tribe, based in Arizona.
The mutated gene controls the construction of a threadlike protein structure, called the beta-3-andrenergic receptor, woven into the surface of fat cells. Scientists have long suspected that the receptor plays a role in the way the body regulates its weight.
Pharmaceutical companies, acting on this hunch, have been developing drugs, called ``beta-3 agonists,'' for the past 13 years.
``These beta-3 agonists turn out to be very effective anti-obesity and anti-diabetes agents, particularly in rats,'' said Shuldiner. ``There is some evidence that they're effective in humans as well.''
by CNB