Given the lack of additional molecular features typically associated with IDH-wild-type glioblastoma in any of the institutional or public subclonal astrocytomas (EGFR amplification, simultaneous gain of chromosome 7/loss of chromosome 10, and TERT promoter mutation) as well as the DNA methylation profiling result consistent with IDH-mutant astrocytoma in institutional case 1 and all 13 of the publicly available subclonal cases for which DNA methylation profiling classification data were available, it is unlikely that these tumors represent IDH-wild-type glioblastomas with late IDH1 mutation. This evidence concerns the gene IDH1 and glioblastoma.