Cholesterol, 7-dehydro-

Uses7-Dehydrocholesterol is a vitamin D3 precursor, which is a sterol found in animals. Vitamin D3 is produced by the action of sunlight or ultraviolet irradiation from the precursor, 7-dehydrocholesterol (7-DC), that is synthesized in the skin of animals and humans.In most tissues of the body, 7-dehydrocholesterol is the immediate precursor of cholesterol. It is reduced to cholesterol by the enzyme 3β-hydroxysterol-Δ7-reductase (DHCR7) in the last step of cholesterol biosynthesis. 7-DHC accumulates in Smith-Lemli-Opitz syndrome (SLOS), a disorder characterized by a mutation in the DHCR7 gene and decreased cholesterol levels in bodily tissues and fluids, as well as microcephaly, intellectual disability, and distinctive dysmorphic features. It is highly susceptible to free radical oxidation, giving rise to several oxysterols that may be involved in the pathogenesis of SLOS. 7-DHC levels are increased in brain, liver, and serum in a rat model of SLOS induced by the DHCR7 inhibitor AY 9944. 7-DHC is a provitamin that is converted to vitamin D3 by ultraviolet-B (UVB) light in a human skin equivalent system and in isolated human skin samples.

General Description7-Dehydrocholesterol, a 5,7-conjugated diene sterol is a biosynthetic precursor of cholesterol. It helps in the production of vitamin D3 when exposed to ultraviolet B (UVB) radiation. It has been used as an internal standard to determine sterols. 7-dehydrocholesterol is also used in the diagnosis of Smith-Lemli-Opitz syndrome. Blood and tissue of infants with Smith- Lemli-Opitz (SLO) syndrome contain reduced amounts of cholesterol and greatly increased concentrations of 7-dehydrocholesterol and of its isomer 8-dehydrocholesterol.