Genetic Counselling and Family in IBD: 30 years' Experience at the Cleveland Clinic

The Cleveland Clinic has followed 1288 patients with inflammatorybowel disease (IBD) (437 with mucosa! ulcerative colitis and 851 withCrohn's disease) from 1955 through 1984. Of the 437 patients with mucosalulcerative colitis, the index patient had one or more family members developIBD. These data indicate the need for the treating physician to institute case-findingquestions within the family so that early diagnoses can be established.From 1975 through 1984, 94 patients had a positive family history and 63 hadadditional family members with disease. The highest risk group was the sibling-siblinggroup (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, thelocation of disease in the index patient and the immediate family member wasthe same in 67.5% and different in 30.0%. In this same group of patients, thedisease similarity in the index patient and the immediate family member was thesame in 86.8% and different in 12.0%. These data suggest that while geneticfactors undoubtedly increase the susceptibility for IBD, there is no specificgenetic pattern identified. Also, environmental and other factors may be present.The data also suggest that the age of onset is a factor, perhaps showing increasedassociation with a positive family history