CDKN2A and oligodendroglioma: Astrocytoma exhibited significantly higher amplification proportions of ATRX, TP53 and PDGFRA, except MDM4, and no amplification status for ATRX, TERT, PTEN, CDKN2A/CDKN2B or RB1 was identified in oligodendroglioma (Fig. 2B; Additional file 2: Fig. S2, Additional file 9: Table S2).