P rimary aldosteronism (PA) is the most common form of secondary hypertension, with a prevalence of 5% to 15% among hypertensive patients and is characterized by the autonomous hypersecretion of aldosterone. Sporadic PA and 3 familial forms (familial hyperaldosteronism types I, II, and III) have been described.1 Sporadic PA accounts for >90% of all cases and is caused by either an aldosterone-producing adenoma (APA), which can be surgically removed, or bilateral adrenal hyperplasia, which is treatable with mineralocorticoid receptor antagonists.Somatic APA mutations in the KCNJ5 gene, which encodes the G-protein-activated inward rectifier K + channel 4, GIRK4 (also called the inward rectifier K + channel, Kir3.4), were first identified by Choi et al. 2 Subsequently, Boulkroun et al 3 determined a 34% prevalence of KCNJ5 mutations in a large European cohort of 380 APA. Intriguingly, the KCNJ5 mutations were markedly more prevalent in women, 3 and this predominance was confirmed by successive studies. 4,5 To date, 5 different KCNJ5 mutations causing sporadic PA have been identified, the majority of which are Abstract-Aldosterone-producing adenomas (APAs) cause a sporadic form of primary aldosteronism and somatic mutations in the KCNJ5 gene, which encodes the G-protein-activated inward rectifier K + channel 4, GIRK4, account for ≈40% of APAs. Additional somatic APA mutations were identified recently in 2 other genes, ATP1A1 and ATP2B3, encoding Na + /K + -ATPase 1 and Ca 2+ -ATPase 3, respectively, at a combined prevalence of 6.8%. We have screened 112 APAs for mutations in known hotspots for genetic alterations associated with primary aldosteronism. Somatic mutations in ATP1A1, ATP2B3, and KCNJ5 were present in 6.3%, 0.9%, and 39.3% of APAs, respectively, and included 2 novel mutations (Na