Association of interleukin-18 gene polymorphisms with the outcomes of hepatitis C virus infection in high-risk Chinese Han population

• Association of IL-18 SNPs (−656, −137 and +105) with HCV infection was explored.
• −137C, +105C allele and haplotype GCC, GGC displayed some protective effects.
• IL-18 SNPs were associated with the outcomes of HCV infection in high-risk Chinese.

Interleukin 18 (IL-18) gene polymorphisms have been reported to be associated with the outcomes of hepatitis C virus (HCV) infection in Americans, Indians and Europeans. We aimed to investigate whether the association can be replicated in Chinese Han population. Three IL-18 variants, −656G > T, −137G > C and +105A > C, were genotyped in three independent Han cohorts consisting of 552 cases and 784 controls. By using logistic regression analysis and multiple testing, haplotype GCC were associated with a protection from susceptibility to HCV. After stratified analysis, both the carriage of −137C allele in the older or hemodialysis subgroup and the carriage of +105C allele in the younger subgroup were found to be significantly associated with a decreased risk of HCV susceptibility. By using logistic regression analysis and multiple testing for the resolution of HCV infection, our study showed that +105C allele and haplotype GGC displayed a negative effect on HCV persistence. After stratified analysis, a significantly decreased risk for HCV persistence was found in +105C allele in the subgroups of young, male or female, drug user or hemodialysis and HCV-1 or HCV mixed genotype. No significant association was observed between −656G > T and the outcomes of HCV infection. Our results demonstrated that the carriage of −137C allele, +105C allele, haplotype −656G/−137C/+105C and haplotype −656G/−137G/+105C of IL-18 gene may contribute to better outcomes of HCV infection in high-risk Chinese Han population.