ABCB4 and intrahepatic cholestasis: Indeed, it has been proposed that patients with enough residual ABCB4 activity (≥7%), are better responders to UDCA therapy42, as this is the case for patients with milder forms of ABCB4-related diseases such as low-phospholipid associated cholelithiasis syndrome and intrahepatic cholestasis of pregnancy41–44.