IDH1 and anaplastic astrocytoma: Large-scale analysis confirmed a high prevalence of IDH mutations in oligodendrogliomas (71%) and diffuse astrocytomas (58.6%), with a decreasing frequency in anaplastic astrocytomas (27.6%) and GBMs (10.4%).27 These patterns reinforce IDH mutation status as a key factor in glioma stratification and prognosis.