Table 1.

Subdivision of pediatric GBM into three distinct molecular subgroups.

Category	Mutation/Cytogenetics	Age Distribution	Tumor Location	Prognosis
H3-Mutant	H3K27M H3G34R/V	younger children [42] adolescents and young adults [42,43]	almost exclusively in midline structures (=DMG) [42] cerebral hemispheres [29]	near 100% mortality [44] better OS than H3K27 mutations [44]
IDH-Mutant	IDH 1/2 mutation	older children/young adults [42,43]	cerebral hemispheres, frontal or temporal lobe [29]	better OS than H3-mutants [43]
IDH/H3-Wildtype	BRAFV600E, NF1 mutations, RTK fusions amplifications of EGFR, CDK6, MYCN PDGFRA and MET amplifications	infants/children/adolescents rare in children and adolescents [29] children and adolescents, rather rare [45]	supratentorial, commonly hemispheric [29,44] occur throughout the brain [44] hemispheric and midline [42]	increased survival [42,45] worst OS of WT group [42] poor OS [42,45]

H3 = histone 3, H3K27M = lysine-to-methionin mutation at position 27 in histone 3.1, 3.2 or 3.3; DMG = diffuse midline glioma, OS = overall survival, H3G34R/V = glycine-to-valin or arginine at position 34 in histone 3.3, IDH = isocitrate dehydrogenase, NF1 = neurofibromatosis type 1, RTK = receptor tyrosine kinase, EGFR = epidermal growth factor receptor, CDK6 = cyclin dependent kinase 6, MYCN = proto-oncogene, WT = wildtype, PDGFRA = platelet derived growth factor receptor alpha.