1. Known CAH due to 21-hydroxylase deficiency (classic CAH) diagnosed in childhood with documented (at any time) elevated 17-OHP and/or A4 and currently treated with hydrocortisone, prednisone, prednisolone or dexamethasone (or a combination of the aforementioned glucocorticoids) on a stable glucocorticoid therapy for a minimum of 6 months.