title: The -308 G/A polymorphism in TNF-α gene is associated with asthma risk: an update by meta-analysis.
abstract: BACKGROUND
  The -308 G/A polymorphism in TNF-α gene has been extensively investigated for association to asthma; however, results of different studies have been inconsistent. The aim of this study is to comprehensively evaluate the genetic risk of -308 G/A polymorphism in TNF-α gene for asthma.
  
  
  METHODS
  A meta-analysis was carried out to analyze the association between the -308 G/A polymorphism TNF-α gene and asthma risk.
  
  
  RESULTS
  A total of 4717 cases and 5012 controls in 29 case-control studies were included in this meta-analysis. The result indicated that the variant A allele carriers had a 38% increased risk of asthma, when compared with the homozygote GG (odds ratio (OR) = 1.40, 95% confidence interval (CI), 1.13-1.68 for AA + AG vs. GG). In the subgroup analysis by ethnicity, significant elevated risks were associated with A allele carriers in Asians (OR = 1.53, 95% CI = 1.17-2.01 and P = 0.002) but not in Caucasians(OR = 1.06, 95% CI = 0.75-1.50 and P = 0.73). In the subgroup analysis by age, significant elevated risks were associated with A allele carriers in adults (OR = 1.44, 95% CI = 1.14-1.81, and P = 0.002) and children (OR = 1.37, 95% CI = 1.03-1.82, and P = 0.003). In the subgroup analysis by atopic status, significant elevated risks of asthma were associated with A allele carriers in atopic population (OR = 1.68, 95% CI = 1.34-2.10, and P < 0.00001) but not in non-atopic population (OR = 0.98, 95% CI = 0.58-1.68, and P = 0.95).
  
  
  CONCLUSIONS
  Our results suggest that the TNF-α -308 G/A polymorphism contributes to susceptibility to asthma.
authors.affiliation: Department of Respiratory Medicine, West China Hospital of Sichuan University, Chengdu, Sichuan 610041, China.
authors.forename: Yonggang
authors.initials: Y
authors.lastname: Zhang
authors.forename: Jie
authors.initials: J
authors.lastname: Zhang
authors.forename: Can
authors.initials: C
authors.lastname: Tian
authors.forename: Yuling
authors.initials: Y
authors.lastname: Xiao
authors.forename: Chao
authors.initials: C
authors.lastname: He
authors.forename: Xiaobo
authors.initials: X
authors.lastname: Li
authors.forename: Amrit
authors.initials: A
authors.lastname: Bogati
authors.forename: Jin
authors.initials: J
authors.lastname: Huang
authors.forename: Hong
authors.initials: H
authors.lastname: Fan
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000483:Alleles; D001249:Asthma / Q000235:genetics*; D002648:Child; D002675:Child, Preschool; D016208:Databases, Factual; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006801:Humans; D008875:Middle Aged; D011110:Polymorphism, Genetic; D017594:Publication Bias; D012307:Risk Factors; D012680:Sensitivity and Specificity; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics*; D055815:Young Adult
chemical_list: D014409:Tumor Necrosis Factor-alpha