MONDAY, March 18, 2002 (HealthDayNews) -- When people starve themselves to be thin, experts often blame society for fostering unhealthy images of beauty.
However, researchers have long suspected that genetics also play a role, and now some think they're on the trail of specific genes for anorexia nervosa.
Although the genes don't cause anorexia in everyone who has them, they appear to make people susceptible to the disorder, says Dr. Wade Berrettini, the co-author of a new study into anorexia genes and the director of the Center for Neurobiology and Behavior at the University of Pennsylvania Medical Center.
"We hope we will take this genetic information and try to make an effective medicine," Berrettini says.
Anorexia nervosa and other eating disorders affect 8 million Americans, according to the National Association of Anorexia Nervosa and Associated Disorders. Women are the most common sufferers, but a growing number of men are anorexic, too.
Contrary to popular belief, not everyone who is anorexic avoids food. Some eat and then throw up or take laxatives -- known as bingeing and purging -- while some only purge. People with bulimia, another eating disorder, overeat. Some of those suffer from the purging of anorexia.
Researchers have been inching toward a genetic explanation for the disorder. In 2000, a study of anorexic women from across the globe found that many shared a propensity for perfection, a trait experts think could be genetic.
In the latest work, researchers at the University of Pittsburgh studied 200 families in which at least two relatives in each family suffered from restricting anorexia nervosa, a specific type of the disease. Sufferers strictly control their diets, but don't engage in bingeing or purging. A total of 650 people provided DNA samples.
This is the first time scientists have launched an extensive search for genetic links in relatives who suffer from anorexia, the researchers say. Their findings appear in the March issue of the American Journal of Human Genetics.
The researchers think they've found genes that may be related to anorexia on chromosome 1; genes on seven other chromosomes may also play a role. In general, humans come with 23 pairs of chromosomes.
The next step will be to specifically identify the gene or genes that may cause vulnerability to anorexia, Berrettini says. Humans have an estimated 35,000 to 50,000 genes.
It is as if the researchers are looking for a person and have narrowed the search to a three-block area of Manhattan instead of the entire city of New York, Berrettini explains. There are hundreds of possible targets.
"We've got to look at each one of these people to see if they're the person," he says.
Experts suspect family life could trigger anorexia in some children if they're already genetically susceptible to it.
"Say they're in a family that's awfully controlling and presents them with a lot of food. That may bring it out," says Dr. Ken Fujioka, director of nutrition and metabolic research at Scripps Clinic in San Diego.
If a genetic link to anorexia is found, doctors may have more ammunition to use when they counsel parents who are anorexic, Fujioka says.
Mothers, for instance, may learn about the genetic risks and tell themselves, "I don't want my daughter to go down this trail. I've got to make changes," he says.
What to Do: For more information on eating disorders, visit the National Association of Anorexia Nervosa and Associated Disorders or the American Anorexia Bulimia Association.
