According to the subsequent analysis of resulting molecular glioma subgroups, we found increasing values of the heme biosynthesis mRNA expression signature in these molecular subgroups from IDH mutant and 1p/19q codeleted oligodendrogliomas WHO grade 2 to IDH mutant and 1p/19q codeleted oligodendrogliomas WHO grade 3, IDH mutant astrocytomas WHO grade 2, IDH mutant astrocytomas WHO grade 3, IDH mutant astrocytomas WHO grade 4 and IDH wild type glioblastomas WHO grade 4. This evidence concerns the gene IDH1 and astrocytoma (excluding glioblastoma).