Some researchers said they found the plant gene link surprising. He did not participate in the studies. So it's a very ancient part of the immune system. Crohn's disease causes severe diarrhea, bleeding, fever and malnutrition. It is closely related to ulcerative colitis, so doctors often group the two disorders as inflammatory bowel disease.
Researchers believe that immune cells in the gut overreact to the presence of bacteria.
The resulting inflammation causes the intestinal lining to ulcerate and break down. The United States study tested DNA supplied by 416 families with a history of Crohn's disease. The French study tested 235 families. Both groups, building on earlier studies, focused on Chromosome 16. The researchers said the Nod2 gene was found in primitive defense cells called monocytes that engulf invading microbes.