The formation of bile is an osmotic process driven by the active secretion of biliary constituents out of the hepatocyte into the bile canalicular lumen. Several transport proteins, mainly atp-dependent proteins localized at the canalicular membrane, play roles in bile formation. Recently it has become clear that an increasing number of genetic cholestatic liver diseases in humans can be ascribed to mutations in genes encoding specific transporters. Progressive familial intrahepatic cholestasis (pfic) can now be divided into at least 4 subgroups. In this article, the responsible genes and characteristics of pfic type 1, 2, 3 and 4 are discussed. New diagnostic and therapeutic strategies for cholestatic diseases will be available in the near future.
