Mutations in the bile salt export pump (BSEP, ABCB11) the multidrug resistance protein 3 (MDR3, ABCB4) cause progressive familial intrahepatic cholestasis (PFIC) types II and III, respectively (severe cholestatic liver diseases appearing in early infancy [20,21]). Here, ABCB4 is linked to familial intrahepatic cholestasis.