The mRNA expression signature values increased with the aggressiveness of the molecular subgroups: (1) -28.28 ± 1.92 in IDH mutant and 1p/19q codeleted oligodendrogliomas WHO grade 2, (2) -26.90 + 2.43 in IDH mutant and 1p/19q codeleted oligodendrogliomas WHO grade 3, (3) -26.16 ± 2.27 in IDH mutant astrocytomas WHO grade 2, (4) -25.24 ± 2.80 in IDH mutant astrocytomas WHO grade 3, (5) -23.22 ± 3.78 in IDH mutant astrocytomas WHO grade 4 and (6) -19.55 ± 3.55 in IDH wild type glioblastomas WHO grade 4. Here, IDH1 is linked to oligodendroglioma.