NOD2/CARD15 , ATG16L1 and IL23R gene polymorphisms and childhood-onset of Crohn’s disease

AIM: To assess whether the polymorphisms of NOD2/ CARD15 , autophagy-related 16-like 1 (ATG16L1 ), and interleukin-23 receptor (IL23R ) genes play a more critical role in the susceptibility of childhood-onset than in adult-onset Crohn’s disease (CD). METHODS: Polymorphisms R702W, G908R, and 3020insC of NOD2/CARD15 ; rs2241880 A/G of ATG16L1 , and rs11209026 (R381Q) of IL23R gene were assessed in 110 childhood-onset CD, 364 adult-onset CD, and 539 healthy individuals. Analysis of polymorphisms R702W, G908R, and 3020insC of NOD2/CARD15 genotyping was performed by allele specific polymerase chain reaction (PCR) or by PCR-restriction fragment length polymor-phism analysis. The polymorphisms rs2241880 A/G of the ATG16L1 , and rs11209026 (R381Q) of the IL23R gene in the children’s cohort were genotyped by PCR and melting curve analysis whereas adult group genotyping was performed using the Affymetrix Genome-Wide Human SNP Array 5.0 (500K). RESULTS: The 3020insC allele in NOD2/CARD15 was significantly higher in childhood than in adult-onset CD (P = 0.0067). Association with at least 1 NOD2/CARD15 variant was specific for ileal disease (with or without co- lonic involvement). Even if the frequency of G allele of the rs2241880 ATG16L1 polymorphism was increased in both paediatric and adult CD patients compared to con- trols (P = 0.017 and P = 0.001, respectively), no difference was observed between the childhood and the adult cohort. The rare Q allele of IL23R rs11209026 polymorphism was underrepresented in both paediatric and adult CD cases (P = 0.0018 and P = 0.04, respectively) and no difference was observed between the childhood and the adult cohort. The presence of the rs2241880 ATG16L1 and rs11209026 IL23R polymorphisms did not influence disease phenotype. CONCLUSION: Polymorphism 3020insC in NOD2/ CARD15 occurs statistically significantly more often in patients with childhood-onset CD than in patients with adult-onset CD. The ATG16L1 and IL23R variants are associated with susceptibility to CD, but not earlyonset disease.