To compare the utility of CDKN2A HD and the histology-based WHO grading criteria, Appay et al. analysed 428 IDH-mutant astrocytomas (1p/19q non-co-deletion) and 483 anaplastic oligodendrogliomas (1p/19q co-deleted) using a combination of SNP arrays, CGH arrays, and targeted gene panel NGS data. This evidence concerns the gene CDKN2A and astrocytoma (excluding glioblastoma).