IDH1 and glioblastoma: According to previous reports, gcGBMs are characterized by frequent TP53 (90%–70% according to different reports) and PTEN mutations (around 30%), while IDH mutations (5%), EGFR amplification (6%), and CDKN2A homozygous deletion (3%) are rare.7–10 These differences in the frequency of genetic alterations prompted some authors to place gcGBM in an intermediate position between IDHwt and IDH-mutant (IDHmut) GBM,9 sharing clinical and molecular characteristics with both types of tumors.