CACNA1D and adenoma: Although zona glomerulosa (ZG) is the main physiological site for aldosterone production, in the adult adrenal gland aldosterone synthase expression is suppressed in the majority of the ZG cells and confined to the aldosterone-producing cell clusters,1 which carry somatic mutations in the same genes (ATP1A1, ATP2B3, CACNA1D) that induce constitutive CYP11B2 expression and aldosterone production in aldosterone producing adenomas (APAs).2–4