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

Smith-Lemli-Opitz syndrome (SLOS) is a hereditary disorder in which a defective gene encoding 7-dehydrocholesterol reductase causes the accumulation of noncholesterol sterols, such as 7- and 8-dehydrocholesterol. Using rigorous analytical methods in conjunction with a large collection of authentic standards, we unequivocally identified numerous noncholesterol sterols in 6 normal and 17 SLOS blood samples. Plasma or erythrocytes were saponified under oxygen-free conditions, followed by multiple chromatographic separations. Individual sterols were identified and quantitated by high performance liquid chromatography (HPLC), Ag+-HPLC, gas chromatography (GC), GC-mass spectrometry, and nuclear magnetic resonance. As a percentage of total sterol content, the major C27 sterols observed in the SLOS blood samples were cholesterol (12–98%), 7-dehydrocholesterol (0.4–44%), 8-dehydrocholesterol (0.5–22%), and cholesta-5,7,9(11)-trien-3β-ol (0.02–5%), whereas the normal blood samples contained