Defects in steroidogenic enzymes. Discrepancies between clinical steroid research and molecular biology results.
Molecular biology has clarified the understanding of steroidogenic enzyme genetics. Nevertheless, there are discrepancies between fundamental and clinical experience. (1) Why do patients with "pure" 17 alpha-hydroxylase or 17,20-desmolase deficiency exist, when one cytochrome regulates both steps? A case of interest is discussed, who had "pure" 17,20-desmolase deficiency until adolescence, but additional 17 alpha-hydroxylase deficiency thereafter. (2) In 11 beta-hydroxylase deficiency, it was puzzling to find 18-hydroxylated compounds, and, in isolated hypoaldosteronism, normal cortisol, since 11 beta- and 18-hydroxylation were thought to be regulated together. This has now been explained by differences in the fasciculata and glomerulosa. The occurrence of 11 beta-hydroxylase deficiency of 17-hydroxylated steroids only, however, remains enigmatic. (3) 3 beta-Hydroxysteroid dehydrogenase deficiency does not only seem to exist in classic (mutations of type II gene), but also in late-onset cases. In them, no molecular basis could be found. (4) Also, in cholesterol side-chain cleavage, there is an inequity: while evidently one cytochrome regulates 20- and 22-hydroxylation, pregnenolone is formed when 20 alpha OH-cholesterol, but not when cholesterol, is added to adrenal tissue of deficient patients. Other factors (promoters, fusion proteins, adrenodoxin, cAMP-dependent expression of genes, and/or proteases), or hormonal replacement in patients may be responsible for these discrepancies.
Zachmann
M
M
Department of Pediatrics, University of Zurich, Kinderspital, Switzerland.
D000312:Adrenal Hyperplasia, Congenital; D000446:Aldehyde-Lyases / Q000172:deficiency / Q000235:genetics; D002784:Cholesterol / Q000378:metabolism; D002786:Cholesterol Side-Chain Cleavage Enzyme / Q000172:deficiency / Q000235:genetics; D003577:Cytochrome P-450 Enzyme System / Q000172:deficiency / Q000235:genetics; D006801:Humans; D013254:Steroid 17-alpha-Hydroxylase / Q000235:genetics; D013250:Steroid Hydroxylases / Q000172:deficiency* / Q000235:genetics*; D013256:Steroids / Q000096:biosynthesis*
D013256:Steroids; D003577:Cytochrome P-450 Enzyme System; D002784:Cholesterol; D013250:Steroid Hydroxylases; D013254:Steroid 17-alpha-Hydroxylase; D002786:Cholesterol Side-Chain Cleavage Enzyme; D000446:Aldehyde-Lyases