1. This diagram illustrates adrenal, ovarian, and testicular steroidogenic pathways. Under the usual circumstances in humans, 17-OHP is a poor substrate for CYP17A1 (dotted line). In CAH due to 21-OHD, the defect leads to accumulation of progesterone and 17-OHP, which are diverted not only to AD and T but also to additional metabolites such as 16α-hydroxyprogesterone and 21-deoxycortisol. The adrenal cortex also secretes 11β-hydroxyandrostenedione (11OHAD), and 11-ketotestosterone (11KT). In green, steps that are common to adrenals and gonads; in red, those related to gonadal steroids, in dark gray, those related to adrenal steroids, and in blue those involved in the “backdoor pathway.” Δ5 pathway involving pregnenolone through DHEA, and Δ4 pathway involving progesterone through testosterone are indicated. Δ5 steroids are converted to Δ4 steroids by 3β-HSD. 3β-HSD, 3β-hydroxysteroid dehydrogenase; 5α-red, 5α-reductase; 17β-HSD, 17β-hydroxysteroid dehydrogenase; P450aldo, Cytochrome P450 aldosterone synthase; P450aro, Cytochrome P450 aromatase; P450c11, Cytochrome P450 11β-hydroxylase; P450c17, Cytochrome P450 17α-hydroxylase/17,20-lyase; P450c21, Cytochrome P hydroxylase; P450scc, Cytochrome P450 steroid sidechain cleavage; AKR, Aldo-keto reductase; DHEA, Dehydroepiandrosterone; DHT, Dihydrotestosterone; DOC, Desoxycorticosterone; POR, Cytochrome P450 oxidoreductase; SF1, Steroidogenic factor 1; StAR, Steroidogenic acute regulatory protein. (Reproduced with permission from Rey RA, Grinspon RP. Normal male sexual differentiation and aetiology of disorders of sex development. Best Pract Res Clin Endocrinol Metab Apr;25(2): )
Source: Disorders of Sex Development, Greenspan's Basic & Clinical Endocrinology, 10e
Citation: Gardner DG, Shoback D. Greenspan's Basic & Clinical Endocrinology, 10e; 2017 Available at: Accessed: January 02, 2018
Copyright © 2018 McGraw-Hill Education. All rights reserved