Progressive familial intrahepatic cholestasis(PFIC) type 2 is caused by mutations in ABCB11,which encodes bile salt export pump(BSEP).We report a Thai female infant who presented with progressive cholestatic jaundice since 1 mo of age,with normal serumγ-glutamyltransferase.Immunohistochemical staining of the liver did not demonstrate BSEP along the canaliculi,while multidrug resistance protein 3 was expressed adequately.Novel mutations in ABCB11,a four-nucleotide deletion in exon 3,c.90_93delGAAA,and a single-nucleotide insertion in exon 5,c.249_250insT, were identified,with confirmation in her parents. These mutations were predicted to lead to synthesis of truncated forms of BSEP.Immunostaining and mutation analysis thus established the diagnosis of PFIC type 2. We report a Thai female infant who presented with progressive cholestatic jaundice since 1 mo of age, with normal serum γ-glutamyltransferase. Immunohistochemical staining of the liver did not demonstrate BSEP along the canaliculi, while multidrug resistance protein 3 was rendered adequately. Novel mutations in ABCB11, a four-nucleotide deletion in exon 3, c.90_93delGAAA, and a single-nucleotide insertion in exon 5, c.249_250insT, were identified, with confirmation in her parents. These mutations were predicted to lead to synthesis to truncated forms of BSEP. Immunostaining and mutation analysis thus established the diagnosis of PFIC type 2.