IDH2 and central nervous system cancer: The top somatic mutations in the tier 1 list are summarized in Figure 1A. The common genetic alterations include IDH1 (58%), TP53 (58%), ATRX (47%), IDH2 (11%), CIC (13%), SETD2 (13%), PIK3CA (11%), PIK3R1(11%), PTEN (8%), and RB1(8%), which are consistent with previously reported genomic alterations in gliomas [12].