Canadian researchers have isolated a gene that predisposes people to Crohn's disease, a painful inflammatory disorder that causes the intestine to swell and bleed easily.

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.

Randy Sabourin of the Crohn's and Colitis Foundation of Canada has Crohn's. When he was lying in pain in a hospital bed 17 years ago, doctors told him the only way to get him back to work was to remove his large intestine.

Randy Sabourin

Sabourin feels much better but he carries around a colostomy pouch. "It's an amputation of sorts," said Sabourin. "It's not a good solution by any means."

Researchers from the University of Toronto have found that two neighbouring genetic variations on chromosome 5 increase susceptibility to the disease. The discovery gives scientists proof of a genetic link in Crohn's.

"We now know there is something wrong with the proteins at the cell surface on the bowel wall, which causes them to leak and to let toxic substances in," said University of Toronto researcher Peter St. George Hyslop, a co-author of the study in this week's online issue of Nature Genetics.

Peter St. George Hyslop

The toxic substances damage the bowel wall, causing an inflammatory reaction, Hyslop said. The cell surface protein doesn't work properly in a majority of Crohn's patients.

Sabourin said the discovery may help people find out if they're predisposed to the disease. By testing for the protein malfunction, doctors could distinguish between Crohn's and ulcerative colitis, the other major form of inflammatory bowel disease.

The discovery is not a cure, and researchers believe Crohn's is triggered by environmental factors like diet or exposure to disease, as well as other genes.

Scientists hope the study will help them to develop new approaches to treating Crohn's.