IDH1 and glioblastoma: Glioblastomas are divided in the 2016 World Health Organization’s WHO Classification of Tumors of the Central Nervous System [5,8] into two groups, based on genetic mutations in isocitrate dehydrogenase genes (IDH1 and IDH2): IDH-WT GB (90% of cases), defined as primary or de novo glioblastoma, and IDH-mutant GB, called secondary glioblastoma, with a history of previous lower-grade diffuse glioma.