IDH2 and glioblastoma: IDH-mutant GBM is less common [1], characterized by TP53 [6] and alpha-thalassemia/mental retardation X-linked (ATRX) mutations [5], loss of chromosomes 1p and 19q [9,17], LOH of chromosome 10 [8], originating from cells in the frontal lobe, in contrast to the widespread distribution of IDH-wildtype, which may stem from cells in the subventricular zone [17,18] (Table 1).