Classical RAAS, comprised of ACE, Ang I, and angiotensin type I receptor (AT1), is involved in the conversion of angiotensin I (Ang I) by ACE1 to Ang II that is a ligand for both angiotensin receptors AT1 and AT2: when bound to the AT1 receptor, Ang II induces vasoconstriction resulting in hypertension, water retention, thirst response, cardio hypertrophy, tissue fibrosis, and inflammation. The gene discussed is AGT; the disease is hypertensive disorder.