This tumour category includes a broad array of subcategories including diffuse astrocytomas, anaplastic astrocytomas, IDH wild-type and IDH mutant glioblastomas, diffuse midline gliomas, oligodendrogliomas, and anaplastic oligodendrogliomas—with many phenotypic categories being even further delineated with genetic markers [6]. Here, IDH2 is linked to diffuse midline glioma.