IDH1 and astrocytoma (excluding glioblastoma): Grade 4 IDH1/2-mutant astrocytomas and grade 3 oligodendrogliomas showed positive correlations with a range of molecular alterations, while grades 2/3 in IDH1/2-mutant astrocytomas and grade 2 oligodendrogliomas were negatively correlated with nearly all of the same molecular alterations.