CYP27A1 and cerebrotendinous xanthomatosis: Cerebrotendinous xanthomatosis (CTX; OMIM#213700) is a rare autosomal-recessive inborn disorder of bile acid metabolism due to mutations in the CYP27A1 gene(OMIM *606530) located on chromosome 2q33-qter, leading to increased deposition of cholesterol and cholestanol in multiple tissues [1].