Progressive familial intrahepatic cholestasis (PFIC) types 1, 2 and 3 are a group of cholestatic conditions caused by mutations in ATP8B1, ABCB11 and ABCB4 respectively, and defects in TJP2, encoding tight junction protein 2, can also cause severe cholestatic liver disease12. Here, TJP2 is linked to progressive familial intrahepatic cholestasis.