IDH2 and astrocytoma (excluding glioblastoma): Hartmann et al. [6] found IDH2 mutation in 0.9%, 0.9%, 4.7%, and 5.2% in grade 2 astrocytoma, grade 3 astrocytoma, grade 2 oligodendroglioma, and grade 3 oligodendroglioma, respectively. So, IDH2 mutation testing is not done routinely.