LOCATION OF LUPUS GENE IDENTIFIED.

Byline: Peter Modica Medical Tribune News Service

For the first time, researchers have identified the location of a gene that may predispose people to lupus.

After analyzing the genetic material of 43 families with lupus from around the world, the researchers concluded that the location of the gene is in a region near the end of the long arm of human chromosome 1.

The gene appears to exist in whites, Asians and African Americans, Betty P. Tsao, an associate professor of rheumatology at the University of California at Los Angeles, reported in the Feb. 15 issue of the Journal of Clinical Investigation.

``This would suggest that this is a very important gene that controls autoimmunity somewhat independent of ethnicity,'' said study co-author Dr. Bevra H. Hahn, chief of rheumatology at UCLA.

In people with lupus, the body's immune system attacks itself, causing severe swelling of blood vessels, kidney disorders and tumors of the skin and nervous system. The cause is unknown, but four times more women than men suffer from the disease.

Common signs of lupus include painful or swollen joints, sensitivity to the sun, unusual hair loss and a red rash often in the shape of a butterfly across the bridge of the nose and cheeks.

``The finding that this gene appears to play a role across ethnic groups is very exciting. It suggests that this is going to be an important gene for explaining what causes lupus,'' said Dr. Susana Serrate-Sztein, chief of the rheumatic diseases branch at the National Institute of Arthritis and Musculoskeletal and Skin Diseases. NIAMS, a branch of the National Institutes of Health in Bethesda, Md., helped fund the new study.

Previous studies have suggested that a person who has a family member with lupus has a 20-fold increased risk of developing the disease compared with the general population, said Dr. Brian L. Kotzin, a rheumatologist with the National Jewish Medical and Research Center in Denver.

``We feel that this study provides new insight into the genetic basis of lupus and narrows the cause of the disease,'' said Duane Peters, a spokesperson for the Lupus Foundation of America in Rockville, Md., which also funded the research.

Now that researchers have narrowed the region where the gene may lie, the next step is to define which gene is involved in lupus and what role it plays in the disease.

Researchers would then look for ways to modify and correct malfunctioning genes, Salmon said.