IDH1 and central nervous system cancer: In CNS 5, Pediatric-type diffuse gliomas are categorized into four distinct categories, with their histone mutation status playing a central role in their delineation: 1) Diffuse midline glioma, H3 K27-altered, 2) Diffuse hemispheric glioma, H3 G34-mutant, 3) Diffuse pediatric-type high-grade glioma, H3-wildtype and IDH-wildtype and 4) Infant-type hemispheric glioma (4).