Clinical patterns of familial inflammatory bowel disease.

BACKGROUND Although many recent studies have shown the increased risk of inflammatory bowel disease in relatives of patients with Crohn's disease and ulcerative colitis, clinical patterns of disease within families remain relatively poorly documented. AIMS In this study, clinical characteristics (disease type, extent, age on onset, need for surgery, and presence of extraintestinal manifestations) have been compared in affected subjects in multiply-affected families, with inflammatory bowel disease. METHODS 54 families in whom one parent and at least one child were affected (a total of 77 parent-child pairs) and 155 families in whom at least two siblings were affected (a total of 190 affected sibling pairs) were involved. RESULTS In affected parent-child pairs, parent and child were concordant for disease type in 58 of 77 pairs (75.3%), for extent in 63.6%, extraintestinal manifestations in 70.1%, and smoking history in 85%. The median age of onset in parents was significantly higher than offspring (p < 0.0001). In 40 pairs, 60.6%, the parent was at least 10 years older than child. Siblings were concordant for disease type in 81.6% of the affected sibling pairs, extent in 76.0%, extraintestinal manifestations in 83.8%, and smoking history in 81.3%. In contrast with the parent-child pairs, 68.1% (111 sibling pairs) siblings were diagnosed within 10 years of each other. The median age of onset was 24.0 years. CONCLUSIONS This study has shown consistent clinical patterns in many families with inflammatory bowel disease. The differences in age of onset between parents and children are not readily explained by a simple cohort effect or ascertainment bias, and may reflect effects of genetic factors, producing anticipation between generations.