In a cohort of patients with possible CKD who started an ACE inhibitor, Johnson et al. identified seven patient characteristics that predicted 90-day risk of hyperkalemia: advanced age (80–89 years), pre-existing declining kidney function, diabetes, heart failure, high starting dose of ACEi (ramipril > 10 mg/day), current use of potassium supplements, and current use of ARBs or potassium-sparing diuretics [24]. The gene discussed is ACE; the disease is Hyperkalemia.