Researchers scanned the entire genome of 6,000 people and identified a handful of genes that increase the risk of developing Crohn's disease, according to a report Sunday in the journal Nature Genetics.

The study confirms the often debilitating inflammatory bowel ailment has a strong genetic component. Previous studies had identified two genes involved in the disease.

"I think at this point we have probably up to about eight or nine genes, depending on how you define it," said John Rioux of the Montreal Heart Institute and the University of Montreal, who led the team of Canadian and U.S. researchers.

The researchers said the findings showed genetics play a crucial role in the disease, although environmental factors also are involved. For example, smoking raises one's risk.

Pinpointing the genes that predispose people to Crohn's disease, the researchers said, could help lead to new ways to treat it.

The disease can cause abdominal pain, diarrhea, rectal bleeding, weight loss and arthritis. It is commonly diagnosed in people between the ages of 20 and 30.

"We have been working toward this for over 10 years to try to put all the pieces together," Rioux said in a telephone interview. "To finally get to this stage where we can look at the entire genome and actually discover a handful of genes, it's very, very gratifying."

Scientists previously had some indications of a genetic component to Crohn's disease. It tends to run in families and is more common in certain ethnic groups, especially people of central and eastern European Jewish descent.