title: GSTM1 null genotype contributes to increased risk of male infertility: a meta-analysis.
abstract: BACKGROUND
  Many studies have investigated the association between Glutathione S-Transferase M 1 (GSTM1) null genotype and risk of male infertility, but the impact of GSTM1 null genotype on infertility risk is unclear owing to the obvious inconsistency among those studies. This study aimed to quantify the strength of association between GSTM1 null genotype and risk of male infertility.
  
  
  METHODS
  We searched the PubMed, Embase and Wangfang databases for studies investigating the association between GSTM1 null genotype and risk of male infertility. We estimated pooled odds ratio (OR) with its 95 % confidence interval (95 % CI) to assess this possible association.
  
  
  RESULTS
  Twelve case-control studies with 1, 589 infertility cases and 1, 537 controls were included. Meta-analysis of total 12 studies showed that GSTM1 null genotype was associated with increased risk of male infertility (OR = 1.34, 95%CI 1.02-1.77, P = 0.036). In subgroup analysis of Caucasians, there was also an obvious association between GSTM1 null genotype and increased risk of male infertility (OR = 1.51, 95%CI 1.11-2.05, P = 0.006). Sensitivity analyses by sequential omission of individual studies or omitting studies without high quality did not significantly alter the overall pooled OR. Cumulative meta-analysis further showed a trend of more obvious association as information accumulated. No evidence of publication bias was observed.
  
  
  CONCLUSIONS
  Meta-analyses of available data suggest that GSTM1 null genotype contributes to increased risk of male infertility.
authors.affiliation: Reproductive Medicine Center, Department of Obstetrics and Gynecology, Meizhou People's hospital, Meizhou, 514031, China.
authors.forename: Wu
authors.initials: W
authors.lastname: Chengyong
authors.forename: Yang
authors.initials: Y
authors.lastname: Man
authors.forename: Lin
authors.initials: L
authors.lastname: Mei
authors.forename: Li
authors.initials: L
authors.lastname: Liping
authors.forename: Wen
authors.initials: W
authors.lastname: Xuezhen
mesh_terms: D016022:Case-Control Studies; D016001:Confidence Intervals; D016208:Databases, Factual; D056726:Genetic Association Studies; D005838:Genotype; D005982:Glutathione Transferase / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D007248:Infertility, Male / Q000208:ethnology / Q000235:genetics*; D008297:Male; D016017:Odds Ratio; D012307:Risk Factors; D012680:Sensitivity and Specificity; D044465:White People / Q000235:genetics
chemical_list: D005982:Glutathione Transferase