In this study, we showed that prognostication and possibly classification of young adult glioblastoma can be biomarker-based and demonstrated that a significant portion of young adult glioblastomas could be genetically defined by mutually exclusive BRAF-V600E mutation (15%), H3F3A-K27M mutation (15.9%), H3F3A-G34R/V mutation (2.8%) and IDH1-R132H mutation (16.8%). This evidence concerns the gene IDH1 and glioblastoma.