The fact that high polysomy of EGFR and CEP7 was also seen in IDH-mutant astrocytomas, which rarely have an EGFR amplification, and a glioblastoma appearing to evolve from a low-grade glioneuronal tumor would seem to further indicate that high polysomy is not synonymous with EGFR amplification and that an EGFR/CEP7 ratio is more useful for establishing the presence of EGFR amplification by FISH testing than solely relying on the EGFR copy number. Here, IDH1 is linked to mixed neuronal-glial tumor.