Compared to H3.3 K27M-mutant DMG, IDH-mutant and IDH-wildtype glioblastomas, diffuse hemispheric gliomas, H3 G34-mutant occurred in younger patients, more frequently involved the parietal lobe, more frequently presented as a hemorrhagic tumor at diagnosis, less frequently demonstrated contrast-enhancement and necrosis, more frequently displayed ADC restriction and less frequently expressed Olig2. The gene discussed is OLIG2; the disease is glioblastoma.