title: Reduced C27-steroid 26-hydroxylase activity in heterozygotes for cerebrotendinous xanthomatosis.
abstract: C27-steroid 26-hydroxylase activity in fibroblasts from two heterozygotes for CTX was determined, using an optimized enzyme assay. With 5 beta-cholestane-3 alpha,7 alpha,12 alpha-triol, 5 beta-cholestane-3 alpha,7 alpha-diol, 7 alpha-hydroxy-4-cholestane-3-one or 7 alpha-hydroxycholesterol as substrates, the activities were about 50% of those of control cells. The Km for the substrates was not increased in the CTX heterozygotes. These findings support that deficiency of the C27-steroid 26-hydroxylase is the primary enzymatic defect in CTX.
authors.affiliation: Institute of Clinical Biochemistry, University of Oslo, Rikshospitalet, Norway.
authors.forename: S
authors.initials: S
authors.lastname: Skrede
authors.forename: I
authors.initials: I
authors.lastname: Björkhem
authors.forename: E A
authors.initials: EA
authors.lastname: Kvittingen
authors.forename: C
authors.initials: C
authors.lastname: East
authors.forename: S
authors.initials: S
authors.lastname: Grundy
authors.forename: S
authors.initials: S
authors.lastname: Skrede
mesh_terms: D000328:Adult; D001927:Brain Diseases / Q000201:enzymology* / Q000235:genetics; D002478:Cells, Cultured; D005260:Female; D006579:Heterozygote; D006801:Humans; D008297:Male; D013710:Tendons; D014973:Xanthomatosis / Q000201:enzymology* / Q000235:genetics