Internal validation of multivariate models for glioblastoma, IDH1/2-mutant astrocytoma, and IDH1/2-mutant oligodendroglioma demonstrated relative consistency in model fit, with the greatest heterogeneity observed amongst IDH1/2-mutant oligodendroglioma models (Supplementary Material 11). The gene discussed is IDH1; the disease is oligodendroglioma.