IDH1 and glioblastoma: The previous “World Health Organization Classification of Tumors of the Central Nervous System” (WHO CNS), 2016, based on histopathological diagnosis, used the term glioblastoma, which is divided into three subclasses: Isocitrate Dehydrogenase (IDH) mutant (10%), IDH wild-type (90%), and IDH with not otherwise specified (NOS), each of which presents with a completely different biology and prognosis [12].