ATP8B1 and cholangiocarcinoma: The lack of extrahepatic manifestations typically helps distinguish PFIC1 from PFIC2 as BSEP protein is expressed exclusively in the liver; however, patients with PFIC2 are at risk of developing HCC and cholangiocarcinoma and this can occur as early as 10 months of age.40,48,49 Like those with PFIC1, patients with PFIC2 also have low serum GGT, and normal or near-normal serum cholesterol levels.40 Unlike those with PFIC1, these patients typically have elevated serum aminotransferase at least 5 times the normal value.