Previous studies in large cohorts of IDH-mutant astrocytomas and IDH-wild-type glioblastomas have generated several lines of evidence suggesting that elevated CNA levels and CIN may be present early in the development of a select subset of tumors (prior to developing high-grade histologic or molecular hallmarks), and that this finding has predictive power, identifying glioma subsets with more aggressive behavior and worse clinical outcomes in terms of the patient’s recurrence-/progression-free survival and overall survival. This evidence concerns the gene IDH1 and glioblastoma.