MTHFR and hypertensive disorder: The distributions of hypertension and MTHFR promoter methylation quartiles (β < 0.1338, 0.1338 ≤ β < 0.1385, 0.1385 ≤ β < 0.1423, and β ≥ 0.1423 corresponding to <Q1, Q1–Q2, Q2–Q3, and ≥Q3) among individuals with the rs1801133 genotypes (CC, CT, and TT) were significantly different (P < 0.05).