IDH1 and oligodendroglioma: The World Health Organization's (WHO) classification guidelines now categorize gliomas based on both pathological and molecular characteristics into IDH (isocitrate dehydrogenase)‐mutant diffuse astrocytomas, IDH‐mutant oligodendrogliomas with 1p19q codeletion, and IDH‐wild‐type glioblastomas (GBM) [7, 8, 9].