Vladimír Bzdúch1, Darina Behúlová2, Jozefína Škodová2, Martina Skokňová1, Libor Kozák†
Smith-Lemli-Opitz syndrome (SLOS) is autosomal recessive metabolic-malformation syndrome, caused by a deficiency of 7-dehydrocholesterol reductase affecting the last step of cholesterol biosynthesis. SLOS appears to be most frequent in central European populations (1 : 15-20,000). The clinical diagnosis of SLOS cannot always be made with certainty because of the remarkable variability of clinical phenotype. The discovery of primary defect of cholesterol biosynthesis had important implication for exact diagnosis of patients with SLOS. Biochemical diagnosis of SLOS is now confirmed by gas chromatography/mass spectrometry by finding low serum cholesterol and its abnormally high precursors 7- and 8-dehydro-cholesterol levels. The ultraviolet spectrophotometry determination of serum sterols with 7-dehydrocholesterol accumulation is a reliable and cheap test for screening SLOS. Two techniques, polymerase chain reaction together with restriction analysis (PCR/RFLP) and sequencing are used to detect mutations in the DHCR7 gene.