Renin–angiotensin system (RAS) inhibitors, comprising angiotensin-converting enzyme (ACE) inhibitors and angiotensin II receptor blockers (ARBs), are first-line therapy for essential hypertension and heart failure, and also used as interventions of secondary prevention in coronary heart disease, diabetes mellitus, and diabetic nephropathy.1, 2, 3, 4. The gene discussed is ACE; the disease is diabetic kidney disease.