IDH1 and glioblastoma: Based on this finding, we studied the frequency and putative prognostic importance of mutations in TERTp and ATRX as well as MGMTp methylation in five patient groups, which were classified by 2016 revised WHO classification of CNS tumors: Group 1: ODGs, Group 2: grade III AA (IDH-mutant), Group 3: grade IV GBM (IDH-mutant), Group 4: grade III AA (IDH-WT), and Group 5: grade IV GBM (IDH-WT) [19].