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CYP27A1A gene on chromosome 2q33-qter that encodes a member of the cytochrome P450 superfamily of enzymes, which catalyse reactions involved in drug metabolism and synthesis of cholesterol, steroids and other lipids. CYP27A1 is a mitochondrial protein that oxidises cholesterol intermediates as part of the bile-synthesis pathway. It catalyses the first step in the oxidation of the side chain of sterol intermediates and has a vitamin D3-25-hydroxylase activity. Because the conversion of cholesterol to bile acids is the major route for eliminating cholesterol from the body, CYP27A1 is important for cholesterol homeostasis.
CYP27A1 mutations cause cerebrotendinous xanthomatosis.