Steroidogenic pathways and disruption in 21OHD. Deficiency of CYP21A2 (black bar) impairs mineralocorticoid (aldosterone) and glucocorticoid (cortisol) production. Precursors accumulate and divert to pathways involving CYP17A1 to 19-carbon steroids dehydroepiandrosterone, androstenedione, and T (androgens). Addition of abiraterone acetate blocks CYP17A1-mediated pathways and lowers androgen production. AKR1C3, aldo-keto reductase family 1, member C3; Ang II, angiotensin II; 3βHSD2, 3β-hydroxysteroid dehydrogenase/isomerase type II; StAR, steroidogenic acute regulatory protein; SULT2A1, sulfotransferase family 2A, member 1.