title: Interleukin 18 gene promoter polymorphisms and susceptibility to chronic hepatitis B infection: a review study.
abstract: BACKGROUND
  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.
  
  
  METHODS
  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.
authors.affiliation: Department of Molecular Hepatology, Middle East Liver Disease Center (MELD), Tehran, IR Iran.
authors.forename: Mahsa
authors.initials: M
authors.lastname: Motavaf
authors.affiliation: Department of Molecular Hepatology, Middle East Liver Disease Center (MELD), Tehran, IR Iran ; Department of Anesthesiology and Pain Medicine, Tehran University of Medical Sciences, Tehran, IR Iran.
authors.forename: Saeid
authors.initials: S
authors.lastname: Safari
authors.affiliation: Department of Molecular Hepatology, Middle East Liver Disease Center (MELD), Tehran, IR Iran ; Baqiyatallah Research Center for Gastroenterology and Liver Diseases, Baqiyatallah University of Medical Sciences, Tehran, IR Iran.
authors.forename: Seyed Moayed
authors.initials: SM
authors.lastname: Alavian
keywords: Chronic Hepatitis B; Interleukin-18; Promoter; Single Nucleotide Polymorphism