To the Editor:rnDiagnosis and management of infantile cholestatic liver disease with unknown etiology remain challenging. With recent rapid de- velopment of genetic technology, several gene mutations have been found to be the cause of this disease [1] . Progressive familial intra- hepatic cholestasis (PFIC) is a group of rare diseases that mainly occur in neonates and infants. Some children might progress to end-stage liver disease that requires liver transplantation. Six types of PFICs have been identified. Previous reports have shown that mutations of ATP8B1 [2] , ABCB11 [3] , ABCB4 [4] , TJP2 [5] , NR1H4 [6] , and MYO5B [7] are associated with PFIC 1–6. These genes partici- pate in different processes of bile transport.