IDH2 and glioma: For example, there were 151 IDH + ATRX/TP53-mutated gliomas in the TCGA diffuse glioma datasets of which 73 were of grade II, 65 of grade III and 13 of grade IV (GBM) and median survival was 7.3, 5.2 and 2.8 years (P = 0.0024).