title: A rapid screening procedure for cholesterol and dehydrocholesterol by electrospray ionization tandem mass spectrometry.
abstract: The mono-(dimethylaminoethyl) succinyl (MDMAES) ester is a new derivative for rapid, mild, and sensitive electrospray ionization tandem mass spectrometry (ESI-MS/MS) analysis of cholesterol and dehydrocholesterol. It is an order of magnitude more sensitive than the previous most practical alternative, the N-methylpyridyl ether derivative. The MDMAES derivative was used to develop a rapid screening procedure for the biochemical diagnosis of Smith-Lemli-Opitz syndrome (SLOS) by measuring the dehydrocholesterol/cholesterol ratio in plasma (5 microl) and plasma spotted onto filter paper. Details of the synthesis of [25,26,26,26,27,27,27-(2)H7]-7-dehydrocholesterol, used as a standard for quantitation, are included. The measurement of total sterols as MDMAES esters, after base hydrolysis of plasma, afforded a dehydrocholesterol/cholesterol ratio of 0.05-2.95 for SLOS patient samples (n = 5) compared with 0.001-0.003 for normal adult controls (n = 20). Direct hexane extraction of plasma without base hydrolysis enabled the measurement of free sterols with a total sample analysis time of <1 h. The free dehydrocholesterol/cholesterol ratio was 0.10-4.47 for SLOS patient samples (n = 5) and 0.003-0.011 for normal adult controls (n = 20).
authors.affiliation: Department of Chemical Pathology, Women's and Children's Hospital, 72 King William Road, North Adelaide, South Australia 5006, Australia. david.johnson@adelaide.edu.au
authors.forename: D W
authors.initials: DW
authors.lastname: Johnson
authors.forename: H J
authors.initials: HJ
authors.lastname: ten Brink
authors.forename: C
authors.initials: C
authors.lastname: Jakobs
mesh_terms: D000328:Adult; D002784:Cholesterol / Q000097:blood*; D003684:Dehydrocholesterols / Q000097:blood* / Q000138:chemical synthesis / Q000737:chemistry; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D008403:Mass Screening / Q000379:methods; D012680:Sensitivity and Specificity; D019082:Smith-Lemli-Opitz Syndrome / Q000097:blood / Q000175:diagnosis; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D013997:Time Factors
chemical_list: D003684:Dehydrocholesterols; D002784:Cholesterol