Table 1.
Main characteristics of Progressive Familial Intrahepatic Cholestasis (PFIC)
| PFIC1 (Byler's disease) |
PFIC2 (BSEP deficiency) |
PFIC3 (MDR3 deficiency) |
|
| Transmission | autosomal recessive | autosomal recessive | autosomal recessive |
| Pruritus | severe | severe | moderate |
| Serum GGT activity | normal | normal | high |
| Ductular proliferation | absent | absent | present |
| Serum primary bile acid concentration |
very high | very high | high |
| Bile composition | low primary bile acid concentration |
very low primary bile acid concentration |
low phospholipid concentration |
| Chromosomal locus | 18q21-22 | 2q24 | 7q21 |
| Gene/protein |
ATP8B1 FIC1 |
ABCB11 BSEP |
ABCB4 MDR3 |
| Hepatocyte location | canalicular membrane | canalicular membrane | canalicular membrane |
| Other sites of expression | Cholangiocytes Intestine, Pancreas |
none | none |
| Functional defect | ATP-dependent aminophospholipid transport |
ATP-dependent bile acid transport in bile |
ATP-dependent phosphatidylcholine translocation in bile |