What are the genetic changes related to cerebrotendinous xanthomatosis ?
Mutations in the CYP27A1 gene cause cerebrotendinous xanthomatosis. The CYP27A1 gene provides instructions for producing an enzyme called sterol 27-hydroxylase. This enzyme works in the pathway that breaks down cholesterol to form acids used in the digestion of fats (bile acids). Mutations in sterol 27-hydroxylase impair its ability to break down cholesterol to a specific bile acid called chenodeoxycholic acid. As a result, a molecule called cholestanol, which is similar to cholesterol, accumulates in xanthomas, blood, nerve cells, and the brain. Cholesterol levels are not increased in the blood, but they are elevated in various tissues throughout the body. The accumulation of cholesterol and cholestanol in the brain, tendons, and other tissues causes the signs and symptoms of cerebrotendinous xanthomatosis.