NF2 and meningioma: Accordingly, monosomy 22 is found in around half of meningioma cases, the great majority of NF2-associated meningiomas, as well as between 40-70% of sporadic meningiomas, displaying allelic losses (loss of heterozygosity, LOH) at the 22q12.2 chromosomal region, where the NF2 gene is encoded [1, 3].