NR1H4 and cholestasis: The exact mechanism resulting in cholestasis secondary to ATP8B1 mutations remains unclear, however evidence suggests FIC1 is an aminophospholipid transporter which regulates inner and outer lipid content of the plasma membrane and if mutated may alter the canalicular membrane integrity; additionally FIC1 mutations may lead to alterations in the activity of the farnesoid X receptor (FXR), a nuclear receptor critical to bile acid homeostasis (26, 27).