A study in three European IBD cohorts confirms that the ATG16L1 c.898A > G (p.Thr300Ala) variant is a susceptibility factor for Crohn's disease

Background and aims: A recent study reported that a nonsynonymous SNP rs2241880 (c.898A > G, p.Thr300Ala) within ATG16L1 confers susceptibility to Crohn's disease (CD). We analyzed ATG16L1 c.898A > G in three independent European inflammatory bowel disease (IBD) cohorts from Germany, Hungary and the Netherlands. Methods: In total, we included 910 European IBD patients and compared the ATG16L1 c.898A > G genotype frequency with 707 ethnically matched healthy controls. We included patients from 3 populations originating from Germany (CD n = 310; ulcerative colitis [UC] n = 179), Hungary (CD n = 147; UC n = 117), and the Netherlands (CD n = 157). Subtyping analysis was performed in respect to CARD15 alterations and clinical characteristics. Results: We found a highly significant association of c.898A > G to CD. The association was significant (p = 0.0005) for the total CD cohort but also for the individual populations from Germany (p = 0.02) and Netherlands (p = 0.02) whereas in the Hungarian CD patients a clear trend was observed (p = 0.19; OR 1.227, 95% CI 0.910; 1.654). No association was found between c.898A > G and UC. No statistical interactions were observed between ATG16L1 c.898A > G and CARD15 variants. Furthermore no association to a CD subphenotype was detected. Conclusions: We confirm that ATG16L1 variant c898A > G confers a risk variant for CD but is not associated with a distinct CD phenotype.