BRAF mand CDKN2A deletion define a clinically distinct subgroup of childhood secondary high-grade glioma Alternative lengthening of telomeres is enriched in, and impacts survival of TP53 mutant pediatric malignant brain tumors Genomic analysis of diffuse intrinsic pontine gliomas identifies three molecular subgroups and recurrent activating ACVR1 mutations. Telomerase inhibition abolishes the tumorigenicity of pediatric ependymoma tumor-initiating cells.