Identification of 7(8) and 8(9) unsaturated adrenal steroid metabolites produced by patients with 7-dehydrosterol-delta7-reductase deficiency (Smith-Lemli-Opitz syndrome)

Patients with Smith-Lemli-Opitz syndrome have impaired ability to synthesize cholesterol due to attenuated activity of 7-dehydrosterol-delta(7)-reductase which catalyses the final step in cholesterol synthesis. Accumulation of 7- and 8-dehydrocholesterol is a result of the disorder and potentially these sterols could be used as precursors of a novel class of delta(7) and delta(8) unsaturated adrenal steroids and their metabolites. In this study, we have analyzed urine from SLOS patients in the anticipation of characterizing such metabolites. Gas chromatography/mass spectrometry (GC/MS) was used in the identification of two major metabolites as 7- and 8-dehydroversions of the well-known steroid pregnanetriol. Other steroids, such as 8-dehydro dehydroepiandrosterone (8-dehydro DHEA) and 7- or 8-dehydroandrostenediol were also identified, and several more steroids are present in urine but remain uncharacterized. As yet, the study provides no evidence for the production of ring-B unsaturated metabolites of complex steroids, such as cortisol. We believe that the following transformations can utilize ring-B dehydroprecursors: StAR transport of cholesterol, p450 side chain cleavage, 17-hydroxylase/17,20-lyase, 3beta-hydroxysteroid dehydrogenase, 3alpha-hydroxysteroid dehydrogenase, 17beta-hydroxysteroid dehydrogenase, 20alpha-hydroxysteroid dehydrogenase and 5beta-reductase. We have yet to prove the activity of adrenal 21-hydroxylase, 11beta-hydroxylase or 5alpha-reductase towards 7- or 8-dehydroprecursors.