Sterol-4-alpha-carboxylate 3-dehydrogenase, decarboxylating is an enzyme that in humans is encoded by the NSDHL gene. This enzyme is localized in the endoplasmic reticulum and is involved in cholesterol biosynthesis.
Mutations in the NSDHL gene are associated with CHILD syndrome which is a X-linked dominant disorder of lipid metabolism with disturbed cholesterol biosynthesis, and typically lethal in males.