IDH2 and astrocytoma (excluding glioblastoma): There remains a need for larger, comprehensive single cell sequencing studies (Fig. 4F) in varying grades of IDH-mutant astrocytoma to positively correlate more indirect markers of CIN and to determine high and low levels of CIN within this diffuse glioma subgroup, as well as consensus by expert molecular neuropathologists to set usefully thresholds for CNV level, methylation profiling characteristics, and mRNA expression levels that can be applied in the clinical setting.