Single-nucleotide polymorphism of the MTHFR C677T gene from alanine to valine reduces enzymatic activity, which, in turn, decreases the concentration of 5-methyltetrahydrofolate, which regulates the endothelial cells and nitrite oxides (NO) involved in the pathophysiology of hypertension [3, 4]. The gene discussed is MTHFR; the disease is hypertensive disorder.