The relevance of MTHFR C677T, A1298C, and MTRR A66G polymorphisms with response to male infertility in Asians: A meta-analysis.

Although published studies have reported the association between MTHFR C677T (rs 1801133), A1298C (rs 1801131), and MTRR A66G (rs1801394) polymorphisms and male infertility in Asian populations, the results are conflicting. In order to accurately evaluate the relevance, a meta-analysis was performed.We searched for potential studies in 4 databases, containing PubMed, ScienceDirect, China National Knowledge Infrastructure (CNKI), and Wanfang database until May 31, 2018. The summarized odds ratio (OR) with 95% confidence intervals (95% CI) were calculated to evaluate the relevance in 5 genetic models. The heterogeneity test, sensitivity analysis, and publication bias test was performed by Review Manager 5.3 software.Overall, 22 case-control studies with 5049 cases and 4157 controls were included in this meta-analysis, which contained 20 studies of MTHFR C677T polymorphism, 12 studies of MTHFR A1298C polymorphism and 4 studies of MTRR A66G polymorphism. The results indicated that MTHFR C677T, A1298C, and MTRR A66G polymorphisms were significantly associated with male infertility in Asian populations (Dominant model: MTHFR CC + CT vs TT: OR = 0.60, 95% CI (0.53, 0.67), P <.00001; MTHFR AA + AC vs CC: OR = 0.62, 95% CI (0.49, 0.79), P = .0001; MTRR AA + AG vs GG: OR = 0.60, 95% CI (0.45, 0.81), P = .001. Recessive model: MTHFR CC vs CT + TT: OR = 0.67, 95% CI (0.61, 0.74), P <.00001; MTHFR AA vs AC + CC: OR = 0.79, 95% CI (0.70, 0.88), P <.0001; MTRR AA vs AG + GG: OR = 0.70, 95% CI (0.56, 0.88), P = .002. Heterozygote model: MTHFR CC vs CT: OR = 0.74, 95% CI (0.67, 0.82), P <.00001; MTHFR AA vs AC: OR = 0.83, 95% CI (0.73, 0.93), P = .002; MTRR AA vs AG: OR = 0.76, 95% CI (0.60, 0.92), P = .02. Homozygote model: MTHFR CC vs TT: OR = 0.48, 95% CI (0.41, 0.56), P <.00001; MTHFR AA vs CC: OR = 0.61, 95% CI (0.39, 0.93), P = .02; MTRR AA vs GG: OR = 0.51, 95% CI (0.36, 0.72), P = .0001. Allele model: MTHFR C vs T: OR = 0.70, 95% CI (0.66, 0.75), P <.00001; MTHFR A vsC: OR = 0.82, 95% CI (0.71, 0.95), P = .01; MTRR A vs G: OR = 0.76, 95% CI (0.66, 0.88), P = .00003). Stratified analyses by geographical location and source of controls showed the same results. Sensitivity analyses indicated that the final consequences of this meta-analysis were stable, and the publication biases test had not found obvious asymmetry.This meta-analysis indicates that MTHFR C677T, A1298C, and MTRR A66G polymorphisms are the risk factors with susceptibility to male infertility in Asians.