Aldosterone-Producing Cell Clusters Frequently Harbor Somatic Mutations and Accumulate With Age in Normal Adrenals

CONTEXT: Aldosterone synthase (CYP11B2) immunohistochemistry and next-generation sequencing (NGS) have revealed the frequent presence of aldosterone-producing cell clusters (APCCs) harboring somatic mutations in aldosterone-regulating genes in adrenals from Americans without defined hypertension status. OBJECTIVE: Determine the frequency and somatic mutation status of APCCs in a Japanese nonhypertensive cohort. DESIGN, SETTING, PATIENTS, AND INTERVENTIONS: Adrenals from 837 consecutive autopsies at a Japanese institution, Tohoku University Hospital, were screened to select 107 unilateral adrenal glands from nonhypertensive patients. APCC score (APCC number/adrenal cortex area per case) was assessed by CYP11B2 immunohistochemistry. DNA from all APCCs and adjacent adrenal cortex was subjected to NGS using two panels targeting aldosterone-regulating genes. PRIMARY OUTCOME MEASURE: APCC frequency and somatic mutation spectrum. RESULTS: In 107 adrenals, 61 APCCs were detected (average of 0.6 APCCs per gland). APCC score was positively correlated with age (r = 0.50, P < 0.0001). NGS demonstrated high confidence somatic mutations in 21 of 61 APCCs (34%). Notably, 16 of 21 APCCs (76%) harbored somatic mutations in CACNA1D, the most frequently mutated gene in our previous studies of APCCs in Americans and CYP11B2-positive micronodules in cross-sectional imaging (computed tomography) negative primary aldosteronism (PA), whereas no APCCs harbored mutations in KCNJ5, the most frequently mutated gene in aldosterone-producing adenoma. APCC score was significantly lower than our previous cohort of unilateral computed tomography–negative PA. CONCLUSIONS: APCCs are frequent in nonhypertensive Japanese adrenals, accumulate with age, and frequently harbor somatic mutations (most commonly in CACNA1D). The role of APCCs in PA pathobiology and non-PA hypertension warrants further investigation.