Confirmation of a susceptibility locus for Crohn's disease on chromosome 16

Crohn's disease and ulcerative colitis are related complex genetic disorders producing chronic intestinal inflammation. A susceptibility locus for Crohn's disease, IBD1 (inflammatory bowel disease), has been implicated on chromosome 16. To evaluate IBD1 in a different population using alternative methodology, we tested markers in the region of IBD1. Seventy-two relative pairs with Crohn's disease only, 23 mixed relative pairs (one relative having Crohn's disease, the other, ulcerative colitis), and 5 relative pairs with ulcerative colitis were genotyped in the region of IBD1. Our population consisted of white Americans, with 29% of families of Ashkenazi Jewish descent. Among the Crohn's disease pairs, we found evidence for linkage at IBD1 using multipoint analysis, p = 0.0082. Negative linkage scores were obtained for mixed and ulcerative colitis-only relative pairs. For the entire data set, including mixed relative pairs and relative pairs with ulcerative colitis, there was no significant evidence of linkage. No difference was observed in the evidence of linkage between Jewish and non-Jewish families. Our studies confirm that IBD1 represents a susceptibility locus for Crohn's disease, but not ulcerative colitis.