CYP21A2 and classic congenital adrenal hyperplasia due to 21-hydroxylase deficiency: As early as 1985, a CAH case which had characteristics of both 21-OHD and 17α-hydroxylase deficiency (17-OHD) was reported; however, no mutations were found in the patient in CYP21A2 or CYP17A1, two genes known to underlie these diseases [7].