CDKN2A and glioblastoma: In contrast, while 5/6 NF1-associated gliomas epigenetically aligning with IDH-wildtype glioblastoma harbored either CDKN2A homozygous deletion or CDK4 amplification similar to NF1-associated HGAP, only one of these six tumors had ATRX mutation, and none exhibited piloid features.