The bile salt export pump ABCB11 mediates the release of bile salts from liver cells into bile. Defects in ABCB11 can cause two clinically distinct forms of cholestasis; progressive familial intrahepatic cholestasis 2 (PFIC2; MIM:601847) and benign recurrent intrahepatic cholestasis 2 (BRIC2; MIM:605479). Cholestasis is characterized by the retention of bile acids or salts. Bile acids can damage hepatocytes and bile duct cells leading to inflammation, fibrosis, cirrhosis and eventually carcinogenesis. PFIC2 patients suffer from chronic cholestasis and develop liver fibrosis, cirrhosis and end-stage liver disease before adulthood. BRIC2 patients experience intermittent episodes of cholestasis that resolve spontaneously after weeks or months (Strubbe et al. 2012, Cuperus et al. 2014).