On the other hand, the new 2021 WHO classification of tumors of the CNS primarily grades meningiomas based on molecular factors (including homozygous deletion of CDKN2A/B and TERT promoter mutation) and histological features (such as mitotic figures, cellularity, nuclear-to-cytoplasmic ratio, brain invasion, and necrosis)41. Here, CDKN2A is linked to meningioma.