IDH3A and glioblastoma: According to the 2021 WHO classification, tumor heterogeneity of adult glioma has been grouped into 3 subtypes: Isocitrate dehydrogenase-mutant (IDH-mut) astrocytoma (with no 1p19q co-deletion), IDH-mut oligodendroglioma (with 1p/19q co-deletion), and IDH-WT glioblastoma (GBM) [11].