Direct bisulfite sequencing showed significant hypermethylation of the analyzed region of the DIRAS-1 gene (CpG island 114) in IDH-mutant astrocytic tumors (mean methylation score: 2.15, p = 0.01) and in IDH-mutant and 1p/19q-codeleted oligodendroglial tumors (mean methylation score of 2.38, p = 0.001) compared to non-neoplastic brain tissue (mean methylation score: 1.23). This evidence concerns the gene IDH1 and oligodendroglial tumor.