7-dehydro Cholesterol

7-dehydro Cholesterol (7-DHC) is an immediate precursor of cholesterol.{22849} It is reduced to cholesterol by the enzyme 3B-hydroxysterol-d7-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.{22849,27281} It is highly susceptible to free radical oxidation, giving rise to several oxysterols that may be involved in the pathogenesis of SLOS.{22849} 7-DHC levels are increased in brain, liver, and serum in a rat model of SLOS induced by the DHCR7 inhibitor AY 9944 (Item No. 14611).{22849} 7-DHC is a provitamin that is converted to vitamin D3 (Item No. 11792) by ultraviolet-B (UVB) light in a human skin equivalent system and in isolated human skin samples.{23284,23286}