Carriage of CARD15 variants and smoking as risk factors for resective surgery in patients with Crohn's ileal disease

Summary Background: It is controversial whether CARD15 variants are truly associated with a more severe form of Crohn's disease. The relative role of CARD15 genotype and smoking in Crohn's disease progression is also debated. Aim: To investigate the association between CARD15 variants and history of resective surgery in patients with Crohn's ileal disease, taking into account smoking as a possible confounding factor. Methods: We originally assessed CARD15 genotype in 239 north Italian Crohn's disease patients (mean follow-up: 10.1 ± 8.1 years). We then focused on 193 patients with proven ileal involvement, 70 of whom (36.3%) carried CARD15-mutated alleles (G908R, R702W, L1007fs). Results: Carriage of CARD15 variants was positively associated with family history and ileal-only disease and negatively associated with uncomplicated behaviour at maximal follow-up (P