title: Interleukin-18 promoter gene -607C/A polymorphism and tuberculosis risk: a meta-analysis.
abstract: BACKGROUND
  Numerous studies have evaluated the association between interleukin-18 (IL-18) promoter gene -607C/ A (rs1946518) polymorphism and tuberculosis (TB) risk. However, the results remain apparently conflicting. The aim of this study was to investigate whether IL-18-607C/A polymorphism is associated with susceptibility to TB.
  
  
  METHODS
  Publications addressing the association between the IL-18-607C/A polymorphism and TB risk were selected from the Pubmed, Cochrane Library, Embase, CNKI and Wanfang databases. Data were extracted from the studies by two independent reviewers. Statistical analysis was performed using RevMan 5.0.25 and STATA 11.0 software.
  
  
  RESULTS
  Eight case-control studies with a total of 1166 TB patients and 1734 controls were retrieved. Meta-analysis results showed significant association between IL-18-607C/A polymorphism and TB risk in all comparisons of the A allele versus C allele (OR=1.17, 95% CI 1.05-1.30, P=0.004), AA versus CC (OR=1.43, 95% CI 1.14-1.81, P=0.002), CA+AA versus CC (OR=1.20, 95% CI 1.01-1.42, P=0.04) and AA versus CA+CC (OR=1.30, 95% CI 1.07-1.58, P=0.007). In subgroup analysis by nationality, a significant association between IL-18-607C/A polymorphism and TB risk in the comparisons of A versus C, CA+AA versus CC and AA versus CA+CC (OR=1.22, 95% CI 1.07-1.38, P=0.002; OR=1.31, 95% CI 1.06-1.61, P=0.01; OR=1.32, 95% CI 1.07-1.63, P=0.01, respectively) were found in Chinese population but not in Indian and Iranian populations.
  
  
  CONCLUSIONS
  This study suggests that the -607C/A polymorphism of IL-18 gene would be a risk factor for TB, especially in Chinese population. To further evaluate gene-to-gene and gene-to-environment interactions on -607C/A polymorphism and tuberculosis risk, more studies with thousands of patients are required.
authors.affiliation: Department of Respiratory Medicine, West China Hospital of Sichuan University, Chengdu, Sichuan 610041, China; Division of Pulmonary Diseases, State Key Laboratory of Biotherapy of China, Sichuan University, Chengdu, Sichuan 610041, China.
authors.forename: Dian-Dian
authors.initials: DD
authors.lastname: Li
authors.forename: Liu-Qun
authors.initials: LQ
authors.lastname: Jia
authors.forename: Shu-Jin
authors.initials: SJ
authors.lastname: Guo
authors.forename: Yong-Chun
authors.initials: YC
authors.lastname: Shen
authors.forename: Fu-Qiang
authors.initials: FQ
authors.lastname: Wen
mesh_terms: D020022:Genetic Predisposition to Disease / Q000235:genetics; D006801:Humans; D020382:Interleukin-18 / Q000235:genetics*; D011401:Promoter Regions, Genetic / Q000235:genetics*; D014376:Tuberculosis / Q000453:epidemiology* / Q000235:genetics*
chemical_list: D020382:Interleukin-18