MTHFR C667T rs1801133 polymorphism significantly increased the risk of H-HTN under all genetic models except for the overdominant model (C versus T: OR = 2.17, 95% CI 1.77–2.66, I2 = 71.2%; CC versus TT: OR = 4.36, 95% CI 2.74–6.96, I2 = 70.6%; CC versus CT: OR = 1.59, 95% CI 1.28–1.96, I2 = 33.7%; CT/CC versus TT: OR = 2.19, 95% CI 1.76–2.73, I2 = 46.5%; CC versus TT/CT: OR = 3.23, 95% CI 2.14–4.87, I2 = 71.4%; CC/TT versus CT: OR = 1.08, 95% CI 0.85–1.36, I2 = 57.2%), as shown in Supplementary Figure 2. This evidence concerns the gene MTHFR and hypertensive disorder.