Assays of plasma dehydrocholesteryl esters and oxysterols from Smith-Lemli-Opitz syndrome patients.
Smith-Lemli-Opitz syndrome (SLOS) is caused by mutations in the gene encoding 3β-hydroxysterol-Δ(7)-reductase and as a result of this defect, 7-dehydrocholesterol (7-DHC) and 8-dehydrocholesterol (8-DHC) accumulate in the fluids and tissues of patients with this syndrome. Both 7- and 8-DHC are susceptible to peroxidation reactions, and several biologically active DHC oxysterols are found in cell and animal models of SLOS. Ex vivo oxidation of DHCs can be a confounding factor in the analysis of these sterols and their esters, and we developed HPLC/MS methods that permit the direct analysis of cholesterol, 7-DHC, 8-DHC, and their esters in human plasma, thus avoiding ex vivo oxidation. In addition, three oxysterols were classified as endogenously formed products by the use of an isotopically-labeled 7-DHC (d(7)-7-DHC) added to the sample before workup, followed by MS analysis of products formed. Analysis of 17 SLOS plasma samples shows that 8-DHC linoleate correlates better with the SLOS severity score of the patients than other sterols or metabolites, including cholesterol and 7-DHC. Levels of 7-ketocholesterol also correlate with the SLOS severity score. 8-DHC esters should have utility as surrogate markers of severity in SLOS for prognostication and as endpoints in clinical trials.
Department of Chemistry, Vanderbilt Institute of Chemical Biology and Vanderbilt Kennedy Center for Research on Human Development, Vanderbilt University, Nashville, TN 37235, USA.
Wei
W
Liu
Libin
L
Xu
Connor R
CR
Lamberson
Louise S
LS
Merkens
Robert D
RD
Steiner
Ellen R
ER
Elias
Dorothea
D
Haas
Ned A
NA
Porter
D000293:Adolescent; D000328:Adult; D001774:Blood Chemical Analysis / Q000379:methods*; D001800:Blood Specimen Collection; D002648:Child; D002675:Child, Preschool; D002851:Chromatography, High Pressure Liquid; D003684:Dehydrocholesterols / Q000097:blood* / Q000737:chemistry*; D004952:Esters; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D010084:Oxidation-Reduction; D019082:Smith-Lemli-Opitz Syndrome / Q000097:blood* / Q000175:diagnosis; D053719:Tandem Mass Spectrometry; D055815:Young Adult
D003684:Dehydrocholesterols; D004952:Esters