Fever-causing gene located.

Mediterranean fever is a genetic disorder that causes unpredictable bouts of fever, skin rash, and inflammation of the lungs and joints.

Now, two groups have identified the gene that causes this puzzling disorder. Daniel L. Kastner and Elizabeth Mansfield of the National Institutes of Health in Bethesda, Md., and their colleagues report finding the guilty gene on chromosome 16. Their study appears in the Aug. 22 Cell. In the September Nature Genetics, Jean Weissenbach of Genethon in Evry, France, and her colleagues describe identifying the same gene.

Kastner's team studied people from 62 families with Mediterranean fever who had been treated at clinics in Tel Aviv or Los Angeles. The researchers drew blood and zeroed in on a gene that, when mutated in any of several ways, produces the symptoms of this disease.

Their work suggests that this gene normally makes a protein called pyrin. The defective form, they speculate, directs the cell to produce a flawed copy of the protein. The researchers theorize that normal pyrin shuts off inflammation, the body's response to infection that results in fever, swelling, and pain.

The French researchers found that most of the mutations occur within a small area of DNA. Moreover, the DNA around the mutations was similar in most of the affected people. These findings suggest that the disease was spread by a single individual or small group of people who lived in the Mediterranean region many centuries ago.

Today, Mansfield notes, most people with the disease trace their origins to the Mediterranean basin.