To investigate the role of CCGs in all grades of glioma, including grade 2-4, we firstly analyzed the differential expression of CCGs in glioma grade and found that 11/13 CCGs, except for CLOCK and PER1, were recognized as DEGs in TCGA (Figures 3(a) and 3(b)) and CGGA (Figures 3(c) and 3(d)), respectively. Here, PER1 is linked to central nervous system cancer.