CDKN2A and central nervous system neoplasm: ,24,25 Within CNS tumors, CDKN2A HD is a hallmark of PXA,7 and more recently it has been recognized as an adverse prognostic factor in IDH-mutant diffuse gliomas, pediatric low-grade glial/glioneuronal tumors, supratentorial ependymomas, and meningiomas.26–31