IDH1 and astrocytoma (excluding glioblastoma): Several previous studies included IDH-mutant GBM which is defined as IDH-mutant astrocytoma (WHO grade 4) currently, and examined EGFR Amp, with the ratio ranging from 3% to 16% (Verhaak et al., 2010; Brennan et al., 2013; Li et al., 2019; Wong et al., 2021; Umphlett et al., 2022).