CDKN2A and oligodendroglioma: Another group (cases 4, 5, 6, 7, and 8) demonstrated either broad gains of chromosome 7 or focal amplifications of 7p11.2 including EGFR, and most showed loss of chromosome 10 (including PTEN) as well as heterozygous deletion of 9p with or without focal homozygous deletion of CDKN2A. Several of these cases also had other CNAs previously described in GBM but not oligodendroglioma including PDGFRA amplification (cases 5 and 6) and MDM2 amplification (case 4) [13].