title: Relationship between TNF-<alpha> gene promoter polymorphisms and outcomes of hepatitis B virus infections: a meta-analysis.
abstract: BACKGROUND
  The clearance of hepatitis B virus (HBV) is a complex process which may be influenced by many factors including polymorphisms in the tumor necrosis factor <alpha> (TNF-<alpha>) gene promoter. However, previous reports regarding the relationship between polymorphisms in the TNF-<alpha> promoter and HBV clearance have been inconsistent. Therefore, we performed a meta-analysis on a large population to address this inconsistency.
  
  
  METHODS
  A meta-analysis was performed to examine the association between TNF-<alpha> promoter polymorphisms (-1031T/C, -863C/A, -857C/T, -308G/A and-238G/A) and chronic hepatitis B infection. Odds ratio (OR) and its 95 % confidence interval (CI) were used.
  
  
  RESULTS
  Twelve studies were chosen in our meta-analysis, involving 2,754 chronic HBV infection cases and 1,630 HBV clearance cases. The data showed that TNF-<alpha>-863 CC genotype was significantly associated with HBV clearance (-863 CC vs. AA: OR, 0.64; 95% CI, [0.42, 0.97]; p = 0.04) while patients carrying -308 GG genotype had a significantly increased risk of HBV persistence compared with those with GA or AA genotype (GG vs. GA+AA: OR, 1.35; 95% CI, [1.08, 1.70]; p = 0.01). For the other polymorphisms, no association with HBV infection outcome was found.
  
  
  CONCLUSIONS
  The data showed that polymorphisms -863 A and -308 G in the TNF-<alpha> gene promoter region might be risk factors for HBV persistence. Furthermore, ethnicity might play an important role in HBV infection outcome, leading to conflicting results. More studies on individuals from various ethnic groups will be necessary to determine the role of TNF-<alpha> promoter polymorphisms in the outcome of HBV infection.
authors.affiliation: State Key Laboratory of Infectious Disease Diagnosis and Treatment, College of Medicine, First Affiliated Hospital, Zhejiang University, Zhejiang, China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Xia
authors.forename: Linfu
authors.initials: L
authors.lastname: Zhou
authors.forename: Dongcheng
authors.initials: D
authors.lastname: Liu
authors.forename: Zhi
authors.initials: Z
authors.lastname: Chen
authors.forename: Feng
authors.initials: F
authors.lastname: Chen
mesh_terms: D018740:Genetic Heterogeneity; D005838:Genotype; D006515:Hepatitis B virus / Q000502:physiology*; D019694:Hepatitis B, Chronic / Q000235:genetics*; D006801:Humans; D016017:Odds Ratio; D020641:Polymorphism, Single Nucleotide / Q000235:genetics*; D011401:Promoter Regions, Genetic; D017594:Publication Bias; D012307:Risk Factors; D016896:Treatment Outcome; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics*
chemical_list: D014409:Tumor Necrosis Factor-alpha