The DHCR7 gene encodes delta-7-sterol reductase (EC 1.3.1.21), the penultimate enzyme of mammalian sterol biosynthesis that converts 7-dehydrocholesterol (7-DHC) to cholesterol.
Function: Production of cholesterol by reduction of C7-C8 double bond of 7-dehydrocholesterol (7-DHC).
Tissue Specificity: Most abundant in adrenal gland, liver, testis, and brain.
DISEASE: Defects in DHCR7 are the cause of Smith-Lemli-Opitz syndrome (SLOS)
[MIM:270400]; also known as SLO syndrome or RSH syndrome. SLOS is an autosomal recessive frequent inborn disorder of sterol metabolism with characteristic congenital malformations and dysmorphias. All patients suffer from mental retardation. Children with SLOS have elevated serum 7-dehydrocholesterol (7-DHC) levels and low serum cholesterol levels. SLOS occurs in relatively high frequency: approximately 1 in 20,000 to 30,000 births in populations of northern and central European background. Historically, a clinical distinction often was made between classic ('type I') SLOS and the more severely affected ('type II') patients. There is, in reality, a clinical and biochemical continuum from mild to severe SLOS.
