IDH1 and oligodendroglioma: As per the latest WHO classification (2021), depending on the origin and the mutation of isocitrate dehydrogenase (IDH), three major types of diffuse gliomas are known: astrocytomas (IDH mutant), oligodendroglioma (IDH mutant and 1p/19q co-deleted) and glioblastomas (IDH wild type) [6].