Certain mutations in methylenetetrahydrofolate reductase (MTHFR), angiotensin-converting enzyme (ACE), angiotensin II receptor type 1 (ATR1) and endothelial nitric oxide synthase (eNOS) genes may predispose to high blood pressure [6,7,8,9,10] and to an increased risk for EH, cardiovascular and cerebrovascular diseases. Here, MTHFR is linked to hypertensive disorder.