Dehydrocholesterol reductase deficiency

Dehydrocholesterol Reductase Deficiency, Smith-Lemli-Opitz syndrome (SLOS)... 

Fig. 5.3.6 Diagnose of Smith-Lemli-Opitz syndromesyndrome (SLOS). Urinary dehydropreg-nanetriols (DHPT 5/ -pregn-7-ene-3a,17a,20a-triol and 5j3-pregn-8-ene-3a,17a,20a-triol) partially replace PT in 7-dehydrocholesterol reductase deficiency and can be used to diagnose SLOS. The ratio of DHPT/PT correlates with dehydrocholesterol (DHC)/cholesterol (C) in affected patients (n = 34) and also correlates with clinical severity...

Shackleton CH, Roitman E, Kelley R (1999) Neonatal urinary steroids in Smith-Lemli-Opitz syndrome associated with 7-dehydrocholesterol reductase deficiency. Steroids 64 481-490... 

Sterol-A -isomerase deficiency, known as Conradi-HUnermann syndrome (CDPX2), is an X-linked dominant disorder. Clinical manifestations of this disorder include skeletal abnormalities, chondrodysplasia punctata, craniofacial anomalies, cataracts, and skin abnormalities. The 7-dehydrocholesterol reductase deficiency, known as Smith-Lemli-Opitz syndrome (SLO) is an autosomal recessive disorder occurring in about 1 in 20,000 births. Clinical manifestations of affected individuals include craniofacial abnormalities, microcephaly, congenital heart disease, malformation of the limbs, psychomotor retardation, cerebral maldevelopment, and urogenital anomalies. Measurement of 7-dehydrocholesterol in amniotic fluid during second trimester or in neonatal blood specimen has been useful in the identification of the disorder. The sterol-A " -reductase deficiency causes a developmental phenotype similar to SLO syndrome and is associated with accumulation of desmosterol. The inability of de novo fetal synthesis of cholesterol combined with its inadequate transport from the mother to the fetus appears... 

In disorders which affect cholesterol synthesis (e.g, mevalonic aciduria, 7-dehydrocholesterol reductase deficiency [Smith-Lemli-Opitz syndrome]) there may be markedly reduced bile acid synthesis - these disorders are beyond the scope of his chapter. As indicated in section 3, the synthesis of bile acids involves conversion of C27 bile acids (cholestanoic acids) to their C24 analogues (cholanic acids) and this occurs by a process of )5-oxidation in the peroxisomes. Thus defective bile acid synthesis occurs in disorders of peroxisomal yff-oxidation and in disorders of peroxisome biogenesis. These disorders affect pathways other than the bile acid synthesis pathway and are discussed in Chap. 23. 

---