Are inflammatory bowel diseases hereditary?
The cause of the inflammatory bowel diseases (IBD) ulcerative colitis and Crohn’s disease is not known. However, evidence suggests that these diseases are due to a combination of factors, including genetic predisposition, environmental factors, and changes in the function of the immune system. There is strong evidence to suggest a genetic basis for IBD. Ten percent to 20 percent of people diagnosed with IBD also have a family history of IBD, with the highest risk among first-degree relatives (mother, father, sister, or brother). At this time, a positive family history is the single greatest risk factor for IBD. Relatives of affected individuals have at least a 10-fold increased risk for IBD. Up to 25 percent of patients with IBD have a first-degree relative with the disease, and siblings and children of patients with IBD have a 5 percent to 10 percent risk of developing IBD in their lifetimes. Increased rates of IBD among identical twins compared to fraternal twins, and among siblings
