CYP11B1 and familial hyperaldosteronism: We emphasize key differences between CYP11B1 (11β-hydroxylase) and CYP11B2 (aldosterone synthase) and the onset of a hybrid enzyme – CYP11B1/CYP11B2 –, responsible for aldosterone formation in ZF under ACTH control, in “type I familial hyperaldosteronism” (dexamethasone suppressible).