8-dehydro Cholesterol (8-DHC) is an isomer of the cholesterol precursor 7-DHC . It accumulates in tissues and plasma in patients with Smith-Lemli-Opitz syndrome (SLOS), a disorder characterized by a mutation in DHCR7, the gene encoding 3β-hydroxysterol-Δ7-reductase, and decreased cholesterol levels in bodily tissues and fluids, as well as microcephaly, intellectual disability, and distinctive dysmorphic features. 8-DHC levels are increased in serum in a rat model of SLOS induced by the DHCR7 inhibitor AY 9944 .
