IDH3A and glioblastoma: The 2021 WHO classifies adult diffuse glioma into three categories: low grade glioma (LGG, isocitrate dehydrogenase (IDH) mutant), oligodendroglioma (IDH-mutant and 1p/19q-codeleted) and glioblastoma (IDH-wild type, WHO grade 4, referred to here as GBM) [5].