GBM was divided in: (1) isocitrate dehydrogenase (IDH)-wild type (about 90% of cases), which consists of giant cell glioblastoma, gliosarcoma, epithelioid glioblastoma; (2) IDH-mutant glioblastoma (about 10% of cases); (3) glioblastoma, NOS, for which full IDH evaluation is impossible. This evidence concerns the gene IDH3A and glioblastoma.