Assessed PDGFRA and CDK4 amplification, CDKN2A deletion, TERT promoter mutation, ATRX loss, and p53 expression in IDH-mutant astrocytomas. Multivariate analysis showed correlation with all three markers, and a risk stratification model was suggested using these three alterations. The gene discussed is CDKN2A; the disease is astrocytoma (excluding glioblastoma).