NF1 and meningioma: Molecular genetic alterations that are linked to meningioma tumorigenesis indicate the inactivation of at least one member of the 4.1 super-family of genes, primarily involving the neurofibromin gene, NF2, that is located at 22q12.2 or the 4.1B (DAL-1) gene, located at 18p11.32 (1,2).