Interaction of Th17 differentiations‐related gene polymorphisms and environmental factors contributing to the disease classification, complications, and surgical risks of Crohn's disease in the Chinese Han population.

Objectives: Few studies have been conducted on gene–environment interactions in the Chinese population with Crohn's disease (CD). We aimed to investigate the association between single nucleotide polymorphisms (SNPs) on the T helper 17 (Th17) cell and CD susceptibility/performance in Chinese individuals. Methods: We conducted a case–control and case‐only study at the Peking Union Medical College Hospital. Four SNPs related to the Th17 cell pathway genes were prioritized, including rs2284553 (interferon gamma receptor 2), rs7517847 (interleukin 23 receptor), rs7773324 (interferon regulatory factor 4), and rs4263839 (tumor necrosis factor superfamily 15). SNP frequency was calculated, and gene–environment interaction was assessed by multifactor dimensionality reduction analysis. Results: Altogether 159 CD patients and 316 healthy controls were included. All analyzed SNPs were found in Hardy–Weinberg equilibrium (P > 0.05). The frequency of rs2284553‐A allele and rs4263839‐A allele were lower in CD patients compared with controls (P < 0.05). While the rs4263839‐A allele was more prevalent in ileocolonic CD patients than in those with isolated small intestinal or colonic disease (P = 0.035). Gene–environment interactions revealed associations between rs2284553 and breastfeeding, sunshine exposure, and fridge‐stored food, affecting age at diagnosis, intestinal involvement, and intestinal stricture. Interaction of rs4263839 and breastfeeding influenced small intestinal lesions and intestinal stricture in CD. Conclusions: This study provided information on the genetic background in Chinese CD patients. Incorporating these SNPs into predictive models may improve risk assessment and outcome prediction. Gene–environment interaction contributes to the understanding of CD pathogenesis. [ABSTRACT FROM AUTHOR]