Abstract
The Cleveland Clinic has followed 1288 patients with inflammatory bowel disease (IBD) (437 with mucosa! ulcerative colitis and 851 with Crohn's disease) from 1955 through 1984. Of the 437 patients with mucosal ulcerative colitis, the index patient had one or more family members develop IBD. These data indicate the need for the treating physician to institute case-finding questions within the family so that early diagnoses can be established. From 1975 through 1984, 94 patients had a positive family history and 63 had additional family members with disease. The highest risk group was the sibling-sibling group (6.4% in mucosa! ulcerative colitis and 8.3% in Crohn's disease). Both groups had similar percentages for all immediate family members; namely, 16.5% and 17.3%. In the group of patients reported from 1975 to 1984, the location of disease in the index patient and the immediate family member was the same in 67.5% and different in 30.0%. In this same group of patients, the disease similarity in the index patient and the immediate family member was the same in 86.8% and different in 12.0%. These data suggest that while genetic factors undoubtedly increase the susceptibility for IBD, there is no specific genetic pattern identified. Also, environmental and other factors may be present. The data also suggest that the age of onset is a factor, perhaps showing increased association with a positive family history.