In patients with PFIC1, the well-organized aminophospholipid asymmetry of the CM is disrupted by the impaired function of ATP8B1, leading to a decrease in the transport activity of the bile salt export pump (BSEP), an ABC transporter that is localized on the CM and that predominantly mediates biliary excretion of bile salts[7-10], and subsequently to the onset of severe intrahepatic cholestasis[11]. This evidence concerns the gene ATP8B1 and intrahepatic cholestasis.