Adrenal Hyperplasia, Congenital, Due to 21-Hydroxylase Deficiency, also known as 21-hydroxylase deficiency, is related to classic congenital adrenal hyperplasia due to 21-hydroxylase deficiency and lipoid congenital adrenal hyperplasia. An important gene associated with Adrenal Hyperplasia, Congenital, Due to 21-Hydroxylase Deficiency is CYP21A2 (Cytochrome P450 Family 21 Subfamily A Member 2). The drugs Hydrocortisone-17-butyrate and Dexamethasone have been mentioned in the context of this disorder. Affiliated tissues include adrenal cortex and testes, and related phenotypes are hypertension and fever