IDH2 and glioblastoma: The new classification system integrates phenotypic and genotypic diagnoses, for example, GBM, on the basis of histological diagnosis, which is grouped into GBM IDH-wildtype, GBM IDH-mutant, and GBM NOS (not otherwise specified) with IDH mutational status; thus, patients will benefit from greater diagnostic accuracy as well as improved patient management and more accurate determinations of prognosis and treatment response [6].