,10 Given the chromosomal proximity of MTAP to the CDKN2A locus and the high frequency of concurrent deletions,11 MTAP IHC loss has been suggested as an alternative to evaluate for CDKN2A HD in different CNS and non-CNS tumors, including a recent study in PXA.12–15. Here, CDKN2A is linked to central nervous system neoplasm.