Autophagy 16-like 1 rs2241880 G allele is associated with Crohn's disease in German children

Aim: Genome-wide association studies have described an association of the ATG16L1 (autophagy 16-like 1) gene rs2241880 variant with Crohn's disease (CD). Therefore, we evaluated this polymorphism in early-onset CD in 152 children and 253 controls and for the first time determined ATG16L1 colonic expression in German CD children. Methods: Investigation of rs2241880 allele frequencies using a predesigned single nucleotide polymorphism genotyping assay. Analysis of digenic epistasis between rs2241880 and the three common nucleotide-binding oligomerization domain containing two (NOD2/CARD15) mutations. Determination of ATG16L1 gene expression in large-bowel biopsies of selected patients and controls using real-time polymerase chain reaction. Results: The rs2241880G risk allele frequency was higher in CD compared with controls (63.0% vs. 47.4%; p = 0.0002). No epistasis between NOD2/CARD15 mutations and rs2241880 was observed; however, carriers of both variants had significantly increased disease risk. Transcriptional analysis did not reveal over- or underexpression of ATG16L1 in CD patients compared with controls. Conclusion: We confirmed the association of CD with ATG16L1 rs2241880 variant in early-onset CD. As no epistatic interaction with three common NOD2/CARD15 mutations was observed, the p.Thr300Ala substitution is an independent risk factor for paediatric CD and supports the role for autophagy in disease pathogenesis.