The DHCR7 gene provides instructions for making an enzyme called 7-dehydrocholesterol reductase. This enzyme is involved in the last step responsible for cholesterol production in different cell types. In particular, 7-dehydrocholesterol reductase converts a molecule called 7-dehydrocholesterol to cholesterol. Mutations in DHCR7 gene reduce the ability of 7-dehydrocholesterol reductase to convert 7-dehydrocholesterol to cholesterol. As a result of lack of functional enzyme, cholesterol production is low. In addition, the toxic byproducts of cholesterol production can be accumulated in the blood and other tissues. The above biochemical abnormalities are likely to disrupt the growth and development of many body systems.
Mutation in the DHCR7 gene cause Smith-Lemli-Opitz syndrome.