Thirteen mcPXAs had a + 7/−10 signature in combination with CDKN2A/B deletion; however, none of them had amplifications typical for GBM such as CDK4, CDK6, EGFR, MDM2, MDM4 and MET. Of note, the 13 cases with + 7/−10 signature had a high number of other copy number variations indicating an increased genomic instability (Additional file 2: Table 2). This evidence concerns the gene CDKN2A and glioblastoma.