KCNJ5 and secondary hypertension: Primary aldosteronism (PA) is the most common cause of secondary hypertension, accounting for 4.6% to 14.4% in hypertensive patients.1,2 Choi et al3 first detected somatic and germline mutations in the KCNJ5 gene in APAs, which encodes the potassium channel Kir 3.4 (potassium inwardly rectifying channel, subfamily J, member 5).