Analysis of the intersection of the 28 key genes closely associated with tumor cells in the UTUC revealed 13 key genes (Figure 10E), including ATXN2L, RAN, GALNT1, IGFBP3, S100A11, SEPT9, MARCKS, HPGD, ACTG1, CLDN1, TUBA1C, UPK1B, and YPEL3, which showed differential high expression in tumor cells of UTUC (Supplementary Figure 6). The gene discussed is CLDN1; the disease is neoplasm.