CYP7A1 and breast angiosarcoma: The cause of BA diarrhea includes a deficiency in fibroblast growth factor 19 (FGF-19), a hormone produced in enterocytes in response to high intracellular concentration of BAs and that inhibits hepatic BA synthesis through the downregulation of the rate-limiting enzyme cholesterol 7a-hydroxylase (CYP7A1) [38].