The frequency of homozygous CDK2NA/MTAP deletion is <3% in grade 2 glioma and <10% in grade 2/3 glioma30, sharply contrasting the frequency of homozygous MTAP deletion, which is as high as 50% in grade 4 glioma (GBM)5,39,41. Here, MTAP is linked to glioblastoma.