In the case of PFIC type 3 (PFIC3, or MDR3 deficiency associated with PFIC), mutations affect the ABCB4 gene, which encodes for multidrug resistance protein 3 (MDR3), a floppase involved in the translocation of phosphatidylcholine (PC) from the hepatocyte membrane to the bile. The gene discussed is ABCB4; the disease is hyperinsulinemic hypoglycemia, familial, 4.