IDH1 and astrocytoma (excluding glioblastoma): Although we did not observe the significant correlation between IDH1/2 mutation and higher LINE-1 methylation both among LGGs and GBMs (Figure S2), we showed that LGGs exhibited higher LINE-1 methylation than GBMs did, and oligodendroglial tumors showed higher LINE-1 methylation than astrocytomas (Table 3, Figure 2B), which was consistent with the previous report demonstrating that LGGs, in particular oligodendroglial tumors are characteristics of G-CIMP positive group.