PCDHAC2 and cholangiocarcinoma: Among the 21 candidate genes, ADAMTS10, ANGPTL5, APCDD1L, CCDC85A, CGREF1, CHRDL2, DENND5B, EFS, P4HA3PCD, H20, PCDHAC2, RASGRF2, SLC6A14, TESC, TNMD, and ZNF229 have not been reported in CC; our study is the first to characterize these genes as a prognostic signature.