Study finds genetic basis for anorexia

The study, conducted by a Penn researcher, may lead to new treatments. The same molecule that decides your sex, height and eye color also has a say in whether or not you develop an eating disorder, according to a new study by a University researcher. A recent study of identical twins conducted by the Hospital of the University of Pennsylvania found that anorexia is, at least in part, influenced by a person's DNA. The finding could eventually lead to improved treatments for the disease, which is fatal in 20 percent of its victims who have had the disease for at least 20 years. Approximately one percent of adolescent girls suffer from the eating disorder, which kills more than 1,000 women per year. The disease -- 90 percent of whose victims are female -- is diagnosed when the patient is unable to maintain at least 85 percent of his or her normal body weight. "The twin studies suggest that about half the liability to develop anorexia may be inherited," said Pharmacology Professor Wade Berrettini, author of the report appearing in the winter 1998 issue of Directions in Psychiatry. Berrettini compiled information from various studies of twins and found that both members of a set of identical twins are 10 times more likely to develop anorexia than are two fraternal twins. The finding suggests that a genetic component can predispose victims toward a disease once thought to be purely psychological. "Only a fraction of the people who have the disorder get treatment for it," Berrettini said, explaining that the disorder's negative stigma often leads its victims to deny that they have it. He said that if his research team can identify one or two genes that make a person susceptible to anorexia, "then maybe new medicines can be developed based on genetic susceptibility." Treatment for anorexia has traditionally come in the form of psychotherapy, though some anti-depressant drugs have proven effective in treating the disease. But despite the variety of treatments, none have been approved by the federal Food and Drug Administration as effective agents against anorexia. Having established anorexia as a genetically transmitted disease, Berrettini's next step toward improved treatments is to map the trait to a specific location on human DNA. To that end, Berrettini drew blood samples from about 200 families in which at least two members suffered from anorexia or bulimia, a similar eating disorder which involves binging on food and then vomiting. "I would expect to be able to say where along the human genome the susceptibility genes lie," Berrettini said, adding that the process of finding such genes should take about six months. Last January, Berrettini reported mapping a susceptibility gene for manic depression.