 The DHCR7 gene encodes delta-7-sterol reductase (EC 1.3.1.21), the ultimate enzyme of mammalian sterol biosynthesis that converts 7-dehydrocholesterol (7-DHC) to cholesterol.This enzyme removes the C(7-8) double bond introduced by the sterol delta8-delta7 isomerases.In addition, its role in drug-induced malformations is known