In addition, another one of these metabolites, chenodeoxycholic acid glycine, is the physiological ligand for the farnesoid X receptor and has been approved for the treatment of patients with cerebrotendinous xanthomatosis, who develop abnormal lipid storage with increased plasma and tissue levels of cholesterol (Fiorucci & Distrutti, 2019). This evidence concerns the gene NR1H4 and cerebrotendinous xanthomatosis.