Table 2 showed top 4 genes positively correlated with CHST4 in CCA and top 3 genes negatively correlated with CHST4 in CCA. Expression pattern of correlated genes about CHST4 was delineated (Fig 2). Between the top 4 genes positively correlated and the top 3 genes negatively correlated with CHST4 in CCA, the gene expression correlation are described in Fig 3. The expression profiles of CHST4, CLIP2, ELOVL7, PDGFD, MANEAL, CDKAL1, SFPQ and GUSBL2 were all statistically significant (Fig 4). The gene discussed is PDGFD; the disease is cholangiocarcinoma.