NF2 and meningioma: In contrast, while early clinical studies showed no clear association in meningiomas between NF2 gene mutation and the WHO tumor grade (4, 11), recent reports showed a frequency of NF2 mutation that varies in WHO grade 1 tumors between 20–35% vs 50–72% in grade 2/3 meningiomas (6, 12), and NF2-mutated meningiomas have been reported to display a poorer outcome to that of NF2 wild-type tumors (12, 13).