Genes previously identified in ECO and extrahepatic bile ducts were also expressed by all clusters and did not demonstrate any differences between the anatomical regions of the extrahepatic bile ducts (homeobox B2 (HOXB2), homeobox B3 (HOXB3), aquaporin 5, insulin-like growth factor binding protein 1, ribonuclease T2, laminin subunit beta 3, and lactate dehydrogenase B) (Figure 1B).2, 9, 10 These observations verify the extrahepatic cholangiocyte phenotype of the cells within the ECO and are consistent with the observations of others.9, 10. This evidence concerns the gene RNASET2 and endocrine-cerebro-osteodysplasia syndrome.