CROHNS-DISEASE - CONCORDANCE FOR SITE AND CLINICAL TYPE IN AFFECTED FAMILY MEMBERS - POTENTIAL HEREDITARY INFLUENCES

Background & Aims: The association of genetic influences between bowel location and clinical type of Crohn's disease may provide more inform ation on the genetic heterogeneity of inflammatory bowel disease, The aim of this study was to analyze familial occurences of Crohn's diseas e for concordance for site and type, Methods: Of 554 consecutive patie nts, 95 (17%) had a family history of Crohn's disease, Sixty families were analyzed for concordance for site and clinical type and by a seri es of conditional logistic regression models to test the significance of concordance within families, Results: Eighty-six percent of familie s were concordant in at least 2 members for the site of Crohn's diseas e, and 82% were concordant for clinical type, Pairing family members t ogether, concordance greater than expected in an unrelated population was observed. Using a conditional logistic regression model, a statist ically significant role for concordance in predicting site and type of Crohn's disease in other affected family members was found, Conclusio ns: Greater-than-expected concordance for site and clinical type of Cr ohn's disease within individual families is compatible with a concept of multiple, distinct forms of Crohn's disease, which, although possib ly influenced by environment, seem more likely to be separate inherita ble forms or phenotypes.