DHCR24 encodes a flavin adenine dinucleotide (FAD)-dependent oxidoreductase which catalyzes the reduction of the delta-24 double bond of sterol intermediates during cholesterol biosynthesis. The protein contains a leader sequence that directs it to the endoplasmic reticulum membrane. Missense mutations in DHCR24 have been associated with desmosterolosis. Also, reduced expression of DHCR24 occurs in the temporal cortex of Alzheimer disease patients and overexpression has been observed in adrenal gland cancer cells.