Importantly, homozygous loss of the CDKN2A/B (cyclin-dependent kinase inhibitor 2A/B) locus on chromosome 9p21 was incorporated into the 2021 WHO classification as a defining feature of CNS WHO grade 3 meningioma.3CDKN2A/B encodes for multiple tumor suppressor proteins including p16, which inhibits the G1-to-S transition in the cycle cell through the inactivation of CDK4 and CDK6. This evidence concerns the gene CDKN2A and meningioma.