Therefore, in order to investigate whether aberrant mucin-type O-glycosylation occurs in CCA, the differential expression of O-linked glycosyltransferases (including C1GALT1, COSMC, B3GNT6, and ST6GALNAC1) was investigated through GEO series GSE76297. This evidence concerns the gene C1GALT1C1 and cholangiocarcinoma.