Despite it being an imperfect first-line test for detecting PA (affected by many common medications, time of day, posture, stage of menstrual cycle, and renal impairment), the ARR test may still be valuable for excluding primary aldosteronism when two ARR results on different days are negative and for identifying potential primary aldosteronism where there is a positive ARR or low plasma renin, especially if the patient is taking an ACE inhibitor, angiotensin receptor blocker, or diuretic that should increase renin [2, 4]. The gene discussed is REN; the disease is primary aldosteronism.