The methylenetetrahydrofolate reductase (MTHFR) C677T gene polymorphism has been suggested to be associated with the risk of essential hypertension (EH), however, results remain inconclusive. To investigate this association, the present meta-analysis of 27 studies including 5,418 cases and 4,997 controls was performed. The pooled odds ratio (OR) and its corresponding 95% confidence interval were calculated using the random-effects model. A significant association between the MTHFR C677T gene polymorphism and EH was found under the allelic (OR, 1.32; 95% CI, 1.20-1.45; P=0.000), dominant (OR, 1.39; 95% CI, 1.25-1.55; P=0.000), recessive (OR, 1.38; 95% CI, 1.18-1.62; P=0.000), homozygote (OR, 1.59; 95% CI, 1.32-1.92; P=0.000), and heterozygote (OR, 1.32; 95% CI, 1.20-1.45; P=0.000) genetic models. A strong association was also revealed in subgroups, including Asian, Caucasian and Chinese. The Japanese subgroup did not show any significant association under all models. Meta-regression analyses suggested that the study design was a potential source of heterogeneity, whereas the subgroup analysis additionally indicated that the population origin may also be an explanation. Another subgroup analysis revealed that hospital-based studies have a stronger association than population-based studies, however, the former suffered a greater heterogeneity. Funnel plot and Egger's test manifested no evidence of publication bias. In conclusion, the present study supports the evidence for the association between the MTHFR C677T gene polymorphism and EH in the whole population, as well as in subgroups, such as Asian, Caucasian and Chinese. The carriers of the 677T allele are susceptible to EH.
Keywords: essential hypertension; gene polymorphism; meta-analysis; methylenetetrahydrofolate reductase.