IDH1 and astrocytoma (excluding glioblastoma): Multiple studies have demonstrated that the histologic features separating IDH-mutant glioblastoma from IDH-mutant lower-grade astrocytoma (microvascular proliferation and/or necrosis) remain important prognostic factors, as IDH-mutant glioblastoma has significantly shorter median recurrence-free and overall survival intervals than IDH-mutant grade II or III astrocytomas [4], and IDH-mutant GBMs tend to have higher whole-genome CNV as well as other more specific CNVs and mutations associated with tumor progression and malignancy than their lower-grade counterparts [36,52,67,73].