IDH1 and astrocytoma (excluding glioblastoma): Although alterations in retinoblastoma pathway genes (including RB1, CDKN2A, and CDK4) correlated with poor OS in general, CDKN2A HD alone did not correlate with OS in IDH-mutant astrocytomas (p = 0.19 for univariate and multivariate analysis) or IDH-wildtype astrocytomas (p = 0.57 for univariate analysis and p = 0.88 adjusted) [31].