Sterols in blood of normal and Smith-Lemli-Opitz subjects

Smith-Lemli-Opitz syndrome (SLOS) is a hereditary disorder in which a defec tive gene encoding 7-dehydrocholesterol reductase causes the accumulation o f noncholesterol sterols, such as 7- and 8-dehydrocholesterol. Using rigoro us analytical methods in conjunction with a large collection of authentic s tandards, we unequivocally identified numerous noncholesterol sterols in 6 normal and 17 SLOS blood samples. Plasma or erythrocytes were saponified un der oxygen-free conditions, followed by multiple chromatographic separation s. Individual sterols were identified and quantitated by high performance l iquid chromatography (HPLC), Ag+-HPLC, gas chromatography (GC), GC-mass spe ctrometry, and nuclear magnetic resonance. ks a percentage of total sterol content, the major C-27 sterols observed in the SLOS blood samples were cho lesterol (12-98%), 7-dehydrocholesterol (0.4-44%), 8-dehydrocholesterol (0. 5-22%), and cholesta-5,7,9(11)-trien-3 beta -ol (0.02-5%), whereas the norm al blood samples contained <0.03% each of the three noncholesterol sterols, SLOS and normal blood contained similar amounts of lathosterol (0.05-0.6%) and cholestanol (0.1-0.4%) and similar to0.003-0.1% each of the Delta (8), Delta (8)(14), Delta (5,8)(14), Delta (5,24), Delta (6,8), Delta (6,8)(14) , and Delta (7,24) sterols. The results are consistent with the hypothesis that the Delta (8)(14) sterol is an intermediate of cholesterol synthesis a nd indicate the existence of undescribed aberrant pathways that may explain the formation of the Delta (5,7,9(11)) sterol. 19-Norcholesta-5,7,9-trien- 3 beta -ol was absent in both SLOS and normal blood, although it was routin ely observed as a GC artifact in fractions containing 8-dehydrocholesterol. The overall findings advance the understanding of SLOS and provide a metho dological model for studying other metabolic disorders of cholesterol synth esis. - Ruan, B., W. K. Wilson, J. Pang, N. Gerst, F. D. Pinkerton, J. Tsai , R. I. Kelley, F. G. Whitby, D. M. Milewicz, J. Garbern, and G. J. Schroep fer, Jr. Sterols in blood of normal and Smith-Lemli-Opitz subjects.