Angiotensin II (Ang II) has been shown to induce endothelial dysfunction resulting in increased production of potent oxidants such as peroxynitrite (PN) [10]; therefore, ACE inhibitors (one of the most widely used antihypertensive medications), which not only prevent the formation of Ang II, but also effectively scavenge these potent oxidants, thus protect against cellular damage [11]. The gene discussed is AGT; the disease is endothelial dysfunction.