STAR and hyperinsulinemic hypoglycemia, familial, 4: The most prevalent form of CAH is 21-hydroxylase (21-OH) (90–95% of cases) followed by the next most frequent type of 11β-hydroxylase (11β-OH) (~5% of cases) and other rarer types such as 17α-hydroxylase (17α-OH or 17,20-lyase), 3β-hydroxysteroid dehydrogenase type 2 (HSD3B2), steroidogenic acute regulatory protein (StAR), P450 cholesterol side-chain cleavage enzyme (SCC), P450 oxidoreductase (POR) and cytochrome b deficiency (CYB5A) (2, 3).