CDKN2A and astrocytoma (excluding glioblastoma): Moreover, NGS of glioma is now justified to look for CDKN2A/B homozygous deletions that upgrade IDH-mutant astrocytomas to grade IV, and EGFR amplification, chromosome (+ 7/-10) and TERT promoter mutations that upgrade IDHwt astrocytomas to grade IV.