title: The recent breakthroughs in the understanding of host genomics in hepatitis C.
abstract: BACKGROUND
  Hepatitis C Virus (HCV) infection is spontaneously resolved in about 30% of acutely infected individuals. In those who progress to chronic hepatitis C, HCV therapy permanently eradicates infection in about 40% of cases. It has long been suspected that host genetic factors are key determinants for the control of HCV infection.
  
  
  METHODS
  We will review in this study four genome-wide association studies (GWAS) and two large candidate gene studies that assessed the role of host genetic variation for the natural and treatment-induced control of HCV infection.
  
  
  RESULTS
  The studies consistently identified genetic variation in interleukin 28B (IL28B) as the strongest predictor for the control of HCV infection. Importantly, single nucleotide polymorphisms (SNPs) in IL28B strongly predicted both spontaneous and treatment-induced HCV recovery. IL28B is located on chromosome 19 and encodes interferon-λ, a type III interferon with antiviral activity, which is mediated through the JAK-STAT pathway by inducing interferon-stimulated genes. The SNPs identified in the GWAS are in high linkage disequilibrium with coding or functional non-coding SNPs that might modulate function and/or expression of IL28B. The role of the different IL28B alleles on gene expression and cytokine function has not yet been established.
  
  
  CONCLUSIONS
  These findings provide strong genetic evidence for the influence of interferon-λ for both the natural and treatment-induced control of HCV infection, and support the further investigation of interferon-λ for the treatment of chronic hepatitis C. Furthermore, genetic testing before HCV therapy could provide important information towards an individualized HCV treatment.
authors.affiliation: University Clinic of Infectious Diseases, University Hospital Bern and University of Bern, Bern, Switzerland. andri.rauch@insel.ch
authors.forename: Andri
authors.initials: A
authors.lastname: Rauch
authors.forename: Janine
authors.initials: J
authors.lastname: Rohrbach
authors.forename: Pierre-Yves
authors.initials: PY
authors.lastname: Bochud
mesh_terms: D005260:Female; D055106:Genome-Wide Association Study; D023281:Genomics; D005838:Genotype; D016174:Hepacivirus / Q000187:drug effects*; D006526:Hepatitis C / Q000188:drug therapy*; D006801:Humans; D007372:Interferons; D007378:Interleukins / Q000627:therapeutic use*; D008077:Lipoproteins, LDL / Q000378:metabolism; D008297:Male; D012313:RNA / Q000378:metabolism; D012075:Remission, Spontaneous; D000095022:Interferon Lambda
chemical_list: D007372:Interferons; D007378:Interleukins; D008077:Lipoproteins, LDL; D012313:RNA; C000624353:interferon-lambda, human; D000095022:Interferon Lambda