Adenosine triphosphate-binding cassette, subfamily B, member 4 (ABCB4) gene alterations can cause two distinct clinical entities: progressive familial intrahepatic cholestasis type 3 (PFIC3) and low phospholipid-associated cholelithiasis (LPAC).
The role of an ABCB4 gene defect in liver disease has been initially proven in a subtype of progressive familial intrahepatic cholestasis called PFIC3, a severe pediatric liver disease that may require liver transplantation.
MDR3 and BSEP liver immunostaining, and analysis of biliary lipid composition should help to select PFIC candidates in whom genotyping could be proposed to confirm the diagnosis.
A missense mutation in ABCB4 gene involved in progressive familial intrahepatic cholestasis type 3 leads to a folding defect that can be rescued by low temperature.
Defects of the phospholipid export pump MDR3 ( ABCC4) result in impaired biliary excretion of phosphatidylcholine and a variety of cholestatic syndromes ranging from progressive familial intrahepatic cholestasis in neonates to biliary cirrhosis in adults.
The demonstration of a heterozygous missense mutation in the MDR3 gene in a patient with ICP with no known family history of PFIC, analysed by functional studies, is a novel finding.
Patients with this disease, Progressive Familial Intrahepatic Cholestasis (PFIC) type 3, have a mutation in the MDR3 gene, which is the human homologue of the murine Mdr2 gene.
Among the hereditary human cholestasis, a subtype of progressive familial intrahepatic cholestasis with high gamma-glutamyltranspeptidase (GGT) serum activity shares histological, biochemical, and genetic features with mice lacking mdr2 gene expression (mdr2 -/- mice).