At least 5% of individuals with hypertension have adrenal aldosterone-producing adenomas (APAs). Gain-of-function mutations in KCNJ5 and apparent loss-of-function mutations in ATP1A1 and ATP2A3 were reported to occur in APAs. We find that KCNJ5 mutations are common in APAs resembling cortisol-secreting cells of the adrenal zona fasciculata but are absent in a subset of APAs resembling the aldosterone-secreting cells of the adrenal zona glomerulosa. We performed exome sequencing of ten zona glomerulosa-like APAs and identified nine with somatic mutations in either ATP1A1, encoding the Na(+)/K(+) ATPase α1 subunit, or CACNA1D, encoding Cav1.3. The ATP1A1 mutations all caused inward leak currents under physiological conditions, and the CACNA1D mutations induced a shift of voltage-dependent gating to more negative voltages, suppressed inactivation or increased currents. Many APAs with these mutations were <1 cm in diameter and had been overlooked on conventional adrenal imaging. Recognition of the distinct genotype and phenotype for this subset of APAs could facilitate diagnosis.

Abstract-Primary aldosteronism is the most common form of secondary hypertension. Mutations in the KCNJ5 gene have been described recently in aldosterone-producing adenomas (APAs). The aim of this study was to investigate the prevalence of KCNJ5 mutations in unselected patients with primary aldosteronism and their clinical, biological and molecular correlates. KCNJ5 sequencing was performed on somatic (APA, nϭ380) and peripheral (APA, nϭ344; bilateral adrenal hyperplasia, nϭ174) DNA of patients with primary aldosteronism, collected through the European Network for the Study of Adrenal Tumors. Transcriptome analysis was performed in 102 tumors. Somatic KCNJ5 mutations (p.Gly151Arg or p.Leu168Arg) were found in 34% (129 of 380) of APA. They were significantly more prevalent in females (49%) than males (19%; PϽ10 Ϫ3) and in younger patients (42.1Ϯ1.0 versus 47.6Ϯ0.7 years; PϽ10 Ϫ3 ) and were associated with higher preoperative aldosterone levels (455Ϯ26 versus 376Ϯ17 ng/L; Pϭ0.012) but not with therapeutic outcome after surgery. Germline KCNJ5 mutations were found neither in patients with APA nor those with bilateral adrenal hyperplasia. Somatic KCNJ5 mutations were specific for APA, because they were not identified in 25 peritumoral adrenal tissues or 16 cortisol-producing adenomas. Hierarchical clustering of transcriptome profiles showed that APAs with p.Gly151Arg or p.Leu168Arg mutations were indistinguishable from tumors without KCNJ5 mutations. In conclusion, although a large proportion of sporadic APAs harbors somatic KCNJ5 mutations, germline mutations are not similarly causative for bilateral adrenal hyperplasia. KCNJ5 mutation carriers are more likely to be females; younger age and higher aldosterone levels at diagnosis suggest that KCNJ5 mutations may be associated with a more florid phenotype of primary aldosteronism. H ypertension is a major cardiovascular risk factor that affects between 10% and 40% of the population in industrialized countries. Detection of secondary forms of hypertension is particularly important because it allows for the targeted management of the underlying disease. Primary aldosteronism (PA) is the most common form of secondary hypertension, with an estimated prevalence between 6% and 12% of hypertensives and as high as 20% in patients with resistant hypertension. 1-5 PA occurs as the result of a dysregulation of the mechanisms controlling adrenal aldosterone production, ultimately leading to hypertension with low plasma renin and elevated aldosterone sometimes associated with hypokalemia. Among subtypes of PA, aldosteroneproducing adenoma (APA) and bilateral adrenal hyperplasia (BAH; also known as idiopathic hyperaldosteronism) together account for Ϸ95% of cases. [1][2][3] Aldosterone production from the adrenal zona glomerulosa is tightly controlled to maintain electrolyte and fluid homeostasis by the kidney. Thus, the two most important physiological stimuli of aldosterone secretion are angiotensin II and serum potassium. Glomerulosa cell membrane depolarization leads to openi...