NF2 and meningioma: In contrast with previous studies, mutations in genes other than NF2, which are coded in the vicinity of the NF2 gene at chromosome 22q (e.g., the SMARCB1 gene), were not detected in our patients, suggesting that mutations in these genes (12) are absent or rare (≤5%) in WHO grade 1 meningiomas, and thereby, they would play a limited role in the pathogenesis of WHO grade 1 meningiomas, in contrast with NF2 gene mutations.