In IDH1-mutant astrocytoma cases with available clinical and CNA data (total 161 cases), we found that tumors harboring either CDKN2A deletion, PDGFRA amplification, CDK4 amplification, or MDM2 amplification conferred poor prognosis in these cohorts (Additional file 1: Fig. S5A-B). This evidence concerns the gene CDKN2A and astrocytoma (excluding glioblastoma).