Glucocorticoid-Remediable Aldosteronism (GRA) is an inherited autosomal dominant disorder which causes early-onset (often childhood) high blood pressure, often occuring in individuals with Celtic ancestry.
It typically presents with standard symptoms of aldosteronism (hypertension, hypokalemia, and metabolic alkalosis) with a high aldosterone, low renin state.
The mechanism is pretty cool: the genes for both aldosterone synthetase and 11b-hydroxylase are adjacent genes on the same chromosome which are 95% homologous. Sometimes a crossover event occurs yielding a chimeric gene in which aldosterone synthesis is controlled by ACTH!
The treatment, therefore, is prednisone, to suppress ACTH (and therefore aldosterone).