Abstract
According to the classical scheme cholesterol is converted in the adrenal cortex into pregnenolone and isocaproaldehyde via 20a-OH cholesterol (20α) and 20α:, 22R-di-OH cholesterol (20α, 22R). Earlier we described a 20α-hydroxylase deficiency in postmortem tissue of a patient with CALH (1). Recent experiments in our laboratory showed that adrenal cortex mitochondria in the presence of H2 18O convert cholesterol into pregnenolone and 18O-labeled isocaproaldehyde. A similar experiment with 20α resulted in the formation of 180-labeled pregnenolone. In the presence of H2 18O 22R-OH cholesterol (22R) was converted into 20α, 22R with the 18O attached to the C22 atom. We suggest that cholesterol is converted into pregnenolone and isocaproaldehyde via Δ20-22 cholesterol, 20,22-epoxycholesterol and 20α,22R. We have isolated 20, 22-epoxycholesterol from reaction media. Both chemically and enzymatically the epoxide could be converted into 20α,22R.
According to this new scheme (2) an oxidative desaturase, catalyzing the conversion of cholesterol into Δ20−22 cholesterol, should be deficient in the case described (1).
(1) DEGENHART et al. (1972) Acta Endocr.(Kbh) 71, 512.
(2) KRAAIPOEL et al. (1975) FEES Letters 50, 204.
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Kraaipoel, R., Degenhart, H., Visser, H. et al. LOCALIZATION OF THE ENZYME DEFECT IN A CASE OF CONGENITAL ADRENAL LIPOID HYPERPLASIA (CALH). Pediatr Res 9, 671 (1975). https://doi.org/10.1203/00006450-197508000-00039
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DOI: https://doi.org/10.1203/00006450-197508000-00039