IDH1 and neoplasm: Compared to the group of patients with Grade III tumours, the group with Grade IV tumours had a statistically significantly higher percentage of IDH1-mut tumours (73% vs. 5%, χ2(1) = 56.077, p < 0.001, V = 0.789, 1–b = 0.987) and MGMT promoter methylations (60% vs. 36%, χ2(1) = 7.067, p = 0.008, V = 0.280, 1–b = 0.756).