We identified that 7 genes have basal level difference between cancer and normal cells, including RUNX1 (P-value < 1.4☓10-3), ARHGDIB (P-value < 1.6☓10-2), PSME1 (P-value < 4☓10-2), VAMP5 (P-value < 2☓10-2), POLG (P-value < 1.3☓10-2), GZMB (P-value < 1.44☓10-2), and RBM5 (P-value < 8.2☓10-3), which are mainly due to DNA methylation of the corresponding genes. This evidence concerns the gene POLG and cancer.