Detection of defective 3 beta-hydroxysterol delta 7-reductase activity in cultured human fibroblasts: a method for the diagnosis of Smith-Lemli-Opitz syndrome.
Patients with the autosomal recessive disorder Smith-Lemli-Optiz syndrome (SLO) have recently been shown to have markedly increased tissue levels of certain cholesterol biosynthesis intermediates, most notably 7-dehydrocholesterol. The findings strongly suggest a block in the step that catalyses reduction of 7-dehydrocholesterol to cholesterol. The accumulation of 7-dehydrocholesterol can generally easily be detected in serum by gas chromatography-mass spectrometry. However, it could not be totally ruled out that SLO patients with less severe enzyme defects could escape detection by this method. A more direct way of diagnosing a defect in 7-dehydrocholesterol reduction would be to assay the conversion of 7-dehydrocholesterol to cholesterol in cultured fibroblasts from patients with suspected SLO. In the present work, an assay for the conversion of [3H]lathosterol to [3H]cholesterol in cultured human fibroblasts is described. Lathosterol is the immediate precursor of 7-dehydrocholesterol in the cholesterol biosynthetic pathway and was chosen for the assay instead of 7-dehydrocholesterol owing to the difficulty in preparation and handling of the latter compound. Fibroblasts from control subjects converted [3H]lathosterol to [3H]cholesterol efficiently, whereas in fibroblasts from SLO patients the conversion did not go beyond 7-dehydrocholesterol. It is concluded that the present method is useful for the diagnosis of SLO.
Lund
E
E
Karolinska Institute, Division of Clinical Chemistry, Huddinge Hospital, Sweden.
Starck
L
L
Venizelos
N
N
D002478:Cells, Cultured; D002784:Cholesterol / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D003470:Culture Media; D005347:Fibroblasts / Q000201:enzymology; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D010088:Oxidoreductases / Q000172:deficiency*; D044925:Oxidoreductases Acting on CH-CH Group Donors; D011296:Prenatal Diagnosis; D012867:Skin / Q000166:cytology / Q000201:enzymology; D019082:Smith-Lemli-Opitz Syndrome / Q000175:diagnosis* / Q000201:enzymology*
D003470:Culture Media; C001521:lathosterol; D002784:Cholesterol; D010088:Oxidoreductases; D044925:Oxidoreductases Acting on CH-CH Group Donors; C019995:7-dehydrocholesterol reductase