IDH3A and diffuse midline glioma: These tumors, designated primarily as Grade 4, include the following subtypes: (1) diffuse midline glioma with H3‐K27 alterations (DMG, H3‐K27M), (2) diffuse hemispheric glioma with H3‐G34 mutations (DHG, H3G34M), and (3) diffuse pediatric‐type high‐grade glioma with wild‐type H3 and isocitrate dehydrogenase (pHGG, H3‐WT/IDH WT).