IDH2 and glioblastoma: With the updated 2021 WHO diagnostic criteria, there has been effort to understand the differences between molecular GBM and classic (histologic) GBM.37 We were unable to differentiate these two groups of GBM across all three datasets, including differentiating undersampled GBM versus true molecular GBM.37 Similarly, we were also not able to compare IDH1 versus IDH2 mutations.