Effect of MTHFR A1298C and MTRR A66G Genetic Mutations on Homocysteine Levels in the Chinese Population: A Systematic Review and Meta-analysis.

Background and Objectives: The Chinese population typically has inadequate folate intake and no mandatory folic acid fortification. Methylenetetrahydrofolate reductase (MTHFR) and methionine synthase reductase (MTRR) are the two key regulatory enzymes in the folate/homocysteine (Hcy) metabolism. Hcy has been implicated in the pathogenesis of cardiovascular disease. We conducted a meta-analysis to assess whether the MTHFR gene A1298C and the MTRR gene A66G polymorphisms affect Hcy levels in the Chinese population.

Methods: This analysis included 13 studies with Hcy levels reported as one of the study measurements. Summary estimates of weighted mean differences and 95% confidence intervals (CIs) were obtained using random-effect models.

Results: Overall, there were no significant differences in Hcy concentrations between participants with the MTHFR 1298 CC (12 trials, n = 129), AA ( n = 2166; β, -0.51 μmol/L; 95%CI: -2.14, 1.11; P = 0.53), or AC genotype ( n = 958; β, 0.55 μmol/L; 95%CI: -0.72, 1.82; P = 0.40). Consistently, compared to those with the MTRR 66 GG genotype (6 trials, n = 156), similar Hcy concentrations were found in participants with the AA ( n = 832; β, -0.43 μmol/L; 95%CI: -1.04, 0.17; P = 0.16) or AG ( n =743; β, -0.57 μmol/L; 95%CI: -1.46, 0.31; P = 0.21) genotype. Similar results were observed for the dominant and recessive models.

Conclusions: Neither the MTHFR A1298C polymorphism nor the MTRR A66G polymorphism affects Hcy levels in the Chinese population.