Lack of protective gene linked to Crohn's disease

A new genetic link has been discovered for Crohn's disease, a painful inflammatory disorder that causes the intestine to swell and bleed easily, American and Canadian researchers said Thursday.

More than 150,000 Canadians have Crohn's disease, which is accompanied by severe stomach pains, diarrhea and trouble eating. There is no cure or effective treatment.

Crohn's and colitis are collectively known as inflammatory bowel disease or IBD.

"This pathway is particularly intriguing because we appear to have identified a gene variant that protects against development of IBD, a finding that may lead us to think about the genetics of health as much as about the genetics of disease," said the study's senior author, Dr. Judy Cho, a professor of medicine and genetics at Yale University in New Haven, Conn.

Since the gene has a protective effect, it could be a potential target for new drugs that could help control symptoms of the disease, the researchers said.

Given that IBD tends to run in families and is more common in certain ethnic populations such as Ashkenazi Jews, researchers suspected a genetic link in the disease.

Previous studies have found another mutation linked to the gene, but it alone did not account for all the genetic components of the disease.

1,000 people studied

To find the newest gene, researchers scanned the genomes of more than 500 people with Crohn's disease and another 500 controls. Subjects with Crohn's disease were about fourfold less likely to have the variation, the team reported in Thursday's online issue of the journal Science.

"The gene is called the interleukin-23 receptor, which is a receptoron cells that triggers an inflammatory response in the digestive track," said Dr. Mark Silverberg, a University of Toronto researcher who co-authored the study.

"What we've found is in people who have a defective gene, they are actually protected from getting the disease because you need this gene to actually trigger or initiate inflammatory process," he told CBC Newsworld on Friday.

The gene is also implicated in other autoimmune diseases such as psoriasis, the researchers said.

More needs to be understood about the role of IL-23 in protecting against other diseases before trying to block or manipulate its activity, the researchers cautioned.

The researchers hope the findings will lead to drugs that target the defective pathway, but as with most genetic discoveries, it's likely to be many years before the finding may lead to new treatments for patients.

The next steps are to identify other genes that are thought to be important in Crohn's and tounderstand what interleukin-23doesand how it actually leads tothe disease,Silverberg said.

The research was funded by the U.S. National Institute of Diabetes and Digestive and Kidney Diseases and the Crohn's and Colitis Foundation of Canada.