Interleukin-18 Gene Promoter Polymorphisms and Susceptibility to Chronic Hepatitis B Infection: A Review Study

Context: The variation in clinical outcome of hepatitis B virus (HBV) infection is determined by virological, immunological and host genetic factors. Genes encoding cytokines are one of the candidates among host genetic factors. Polymorphisms in gene promoter can lead to different levels of cytokine expression and unique immune response. Being involved in the inflammatory cytokine network, interleukin-18 (IL-18) plays an important role in pathogenesis of HBV infection. The aim of this review is considering available literature on the association between IL-18 gene promoter single nucleotide polymorphisms (-137 C/G and -607 A/C) and susceptibility to chronic HBV infection.Evidence Acquisition: Published literature from PubMed, EMBASE, and other databases were retrieved. All studies investigating the association of IL-18 gene promoter SNPs, -137 C/G and -607 A/C, with susceptibility to chronic HBV infection were included. Results: Findings showed that the genotype -607A/A is associated with the susceptibility to chronic hepatitis B. Furthermore, allele C at position -137 is suggested to play a protective role against development of chronic HBV infection. Conclusions: Host genetic factors play an important role in determining the outcome of HBV infection. It is suggested that IL-18 genotype -607 A/A is associated with susceptibility to chronic hepatitis B. Furthermore, the carriage of allele C at position -137 may play a protective role in the development of chronic HBV infection.