KCNJ5 and neoplasm: Evidence that KCNJ5 mutations are likely sufficient to cause both aldosterone production and tumor formation is provided by the overall rarity of additional somatic variants in APAs with pathogenic KCNJ5 mutations, specifically the absence of additional mutations that explain proliferation16,28 and the fact that patients with germline KCNJ5 mutations found in APAs typically develop massive adrenal hyperplasia as well as early-onset, therapy-resistant PA (see below)16,29.