IDH1 and glioma: After excluding samples with low tumor purity, we found homogeneous methylation class families in IDH-mutant gliomas CNS WHO grade 2–4, glioblastomas IDH-wildtype, CNS WHO grade 4 and meningiomas, CNS WHO grade 1–2 but distinct molecular subgroups of glioblastoma IDH-wildtype, CNS WHO grade 4 and high-grade meningioma within some of the tumors.