Table 1.

Genetic features of PFIC subtypes

Disease	Byler disease (PFIC 1)	SPGP/BSEP deficiency (PFIC 2)	MDR3 deficiency (PFIC 3)
Chromosome	18q21-q22	2q24	7q21
Gene	FIC 1 (ATP8B1)	BSEP (ABCB11)	PGY3 (ABCB4, MDR 3)
Gene function	FIC1 translocates phospholipids from outer to inner canalicular membrane	Bile salt export pump	Phosphatidylcholine transport into bile

Abbreviations: ABCB11, ATP Binding Cassette Subfamily B Member 11; ABCB4 (PGY3), ATP binding cassette subfamily B member 4; BSEP, bile salt export pump; FIC1, familial intrahepatic cholestasis; MDR3, multidrug resistance Class III; PFIC, progressive familial intrahepatic cholestasis.