ORIGINAL ARTICLE Familial Aggregation and Antimicrobial Response Dose- Dependently Affect the Risk for Crohn’s Disease

Background: An increased risk of Crohn’s disease (CD) has been reported consistently in first-degree relatives of patients. Our aim was to test whether a combination of CD-associated genes involved in innate immunity and/or antibody responses to micro-bial antigens may be valuable in identifying healthy relatives at risk. Methods: We investigated 86 families from Belgium and north-ern France, 45 with at least 3 first-degree relatives with CD, 24 with a single case, and 17 control families without inflammatory bowel disease (IBD). The cohort consisted of 186 CD patients, 290 healthy relatives, and 142 controls (total 618). Genetic (NOD2, NOD1, TLR4, CARD8) and serologic markers (ASCA