Figure 1.

Schematic diagram of steroidogenesis in the placenta, adrenal and gonads, and peripheral tissues. (1) Fetal progesterone derived from the placenta serves as a precursor to the synthesis of aldosterone and cortisol. (2) Loss of 21-hydroxylase activity results in deficiencies of cortisol and aldosterone, as well as elevated levels of 17-hydroxyprogesterone. (3) Loss of 11β-hydroxylase deficiency results in deficiencies of cortisol and aldosterone. (4) In 3βHSD2 deficiency, large amounts of pregnenolone, 17-hydroxypregnenolone and DHEA are secreted. These hormones are converted in the peripheral tissues by the action of 3βHSD-I, resulting in elevated levels of 17-hydroxyprogesterone. 3βHSD-I, 3β-hydroxysteroid dehydrogenase type1; 3βHSD-II, 3β-hydroxysteroid dehydrogenase type 2; 17OH, 17-hydroxy; DHEA, dehydroepiandrosterone.