CYP17A1 and congenital adrenal hyperplasia: Both CYP17A1 and CYP21A2 are associated with congenital adrenal hyperplasia (CAH aka 17OHD), a disorder that leads to abnormal sexual development (Délot et al., 2017), with CYP21A2 mutations being the most common cause of CAH (Koppens et al., 1992).