CLCN2chloride channel mutations in familial hyperaldosteronism type II

Primary aldosteronism, a common cause of severe hypertension1 , features constitutive production of the adrenal steroid aldosterone. We analyzed a multiplex family with familial hyperaldosteronism type II (FH-II)2 and 80 additional probands with unsolved early-onset primary aldosteronism. Eight probands had novel heterozygous variants in CLCN2, including two de novo mutations and four independent occurrences of a mutation encoding an identical p.Arg172Gln substitution; all relatives with early-onset primary aldosteronism carried the CLCN2variant found in the proband. CLCN2encodes a voltage-gated chloride channel expressed in adrenal glomerulosa that opens at hyperpolarized membrane potentials. Channel opening depolarizes glomerulosa cells and induces expression of aldosterone synthase, the rate-limiting enzyme for aldosterone biosynthesis. Mutant channels show gain of function, with higher open probabilities at the glomerulosa resting potential. These findings for the first time demonstrate a role of anion channels in glomerulosa membrane potential determination, aldosterone production and hypertension. They establish the cause of a substantial fraction of early-onset primary aldosteronism. Whole-exome sequencing identifies mutations in CLCN2in individuals with familial hyperaldosteronism type II or early-onset primary aldosteronism. These gain-of-function mutations cause chloride channel opening and glomerulosa cell depolarization, showing a role for anion channels in aldosterone production.