FGF21 reportedly has no effect on expression of cyp7a1, a key enzyme in hepatic bile acids synthesis (17), which is a hallmark of FGFR4-KLB function in the liver; however, it plays notable roles in lipid and glucose metabolism and thus is proposed as a novel pharmacotherapy for obesity and diabetes. The gene discussed is CYP7A1; the disease is obesity due to melanocortin 4 receptor deficiency.