The MTHFR C/T genotype in the co-dominant model (MTHFR C/T vs. MTHFR C/C) (age-, smoking-, and drinking-adjusted OR 1.307, 95% CI 1.039–1.643, P = 0.022) and MTHFR C/T and T/T genotypes in the dominant model (MTHFR C/T plus MTHFR T/T vs. MTHFR C/C) (age-, smoking-, and drinking-adjusted OR 1.281, 95% CI 1.146–1.430, P < 0.001) were significant risk factors for the presence of hypertension (Table 5). Here, MTHFR is linked to hypertensive disorder.