In an advance announcement, the journal Nature is reporting the first discovery of a gene, Nod2, involved in causing Crohn's disease, one of the two major inflammatory bowel diseases that affects nearly 500,000 Americans. The discovery, made by researchers at the universities of Michigan, Chicago and Pittsburgh; the Cleveland Clinic Foundation; and Johns Hopkins may help pave the way for new treatments and prevention strategies for this devastating disease.

"The cause of Crohn's disease has been a mystery for years, and now we have identified an abnormality in the Nod2 gene that makes people susceptible. Nod2 genetic abnormalities probably account for 10 percent to 15 percent of Crohn's cases," says Steven Brant, assistant professor of medicine at Hopkins and director of the Meyerhoff Inflammatory Bowel Disease Genetics Laboratory. The gene and its characterization was led by the universities of Chicago and Michigan.

Nod2 regulates the immune system's response to bacteria and inflammation, and it may cause the disease by interfering with these processes. Nod2 is also in a family of genes that causes apoptosis, programmed cell death. In Crohn's disease, the inner lining if the bowel is inflamed, extending deep into the intestinal wall. It usually involves the small and large intestines. It causes pain, severe diarrhea, intestinal bleeding, weight loss and fever. Symptoms vary in severity and duration; some patients suffer frequent prolonged attacks, and others have fewer recurrences. The disease usually starts in the adolescent or young adult years. Medical therapy can control symptoms and flares, although the majority of patients usually require surgery at some time.

The Meyerhoff Inflammatory Bowel Disease Center, under the direction of Ted Bayless, was established, in part, to investigate genetic mechanisms of Crohn's. Steve Brant was recently awarded nearly $2 million from the National institutes of Health to identify Crohn's disease genes and undertake epidemiological studies.