The present three children had (1) small (<1 cm), bilateral vestibular schwannomas (VSs) detected (as an incidental finding) at magnetic resonance imaging (MRI) by the age of 4 to 5 months that were asymptomatic for 10 to 14 years, with sudden and rapid (<12 months) progression in two cases at the age of 11 and 15 years, respectively; (2) development of large numbers of skin NF2 plaques mainly in atypical locations (i.e. face, hands, legs and knees), which reverted to normal skin appearance at the time of VSs progression; (3) lens opacities (n = 1) and NF2 retinal changes (n = 2) detected as early as age of 3-4 months; (4) diffuse (asymptomatic) high signal lesions at brain MRI in the periventricular regions (alike cortical dysplasia); and (5) unaffected first-degree relatives who did not harbour NF2 gene abnormalities.
However, the application of FISH detection of NF2 gene deletion (NF2 FISH) in differentiation of malignant pleural mesothelioma from reactive mesothelial hyperplasia has not been fully evaluated.
Neurofibromatosis type 2 (NF2) is a rare autosomal dominant disorder (incidence 1:33 000-40 000) characterized by formation of central nervous system tumors, due to mutation in the NF2 gene on chromosome 22q12.
MM shows frequent genetic inactivation of tumor suppressor genes of p16(INK4a)/p14(ARF) and neurofibromatosis type 2 (NF2) which encodes Merlin, and epigenetic inactivation of RASSF1A.
The availability of accurate mouse models of human NF2-associated tumors and the identification of molecules involved in merlin growth regulation now provide an opportunity to design targeted treatments for schwannomas and meningiomas.
Results show that merlin isoform 1 is sufficient to restore normal actin organization in NF2-deficient human tumor cells, demonstrating a key role for merlin in the NF2 phenotype.
Mutations of NF2, the gene for neurofibromatosis 2, are detected in 20-30% of sporadic meningiomas, and almost all mutations lead to loss of merlin expression.
The genetic alterations observed in the NF2 gene indicated that spinal schwannomas are associated with genetic alterations also found in other schwannomas and type 2 Neurofibromatosis, which reinforces the etiological role of this gene.
SPSs express a pattern of biomarkers consistent with the dysregulation of the tumor suppressor merlin observed in neurofibromatosis Type 2-associated schwannomas, suggesting a shared etiology.
In a diverse panel of cancer cell lines, we found that the cells most sensitive to focal adhesion kinase (FAK) inhibition lack expression of the neurofibromatosis type 2 (NF2) tumor suppressor gene product, Merlin.
Last, we found that some NF2 point mutations in merlin most closely resembled gain-of-function alleles in their cellular phenotype, which suggests that mutant NF2 alleles may not always act in a loss-of-function manner, as had been assumed, but may include a spectrum of allelic types with different phenotypic effects on the function of the protein.
Loss of the NF2 tumor suppressor gene is the most common genetic alteration in meningiomas, and the NF2 gene product, Merlin, acts upstream of the Hippo pathway.
Nearly 75% of MM cases have inactivating mutations in the NF2 (neurofibromatosis type 2; Merlin) gene or in downstream signaling molecules of the Hippo signaling cascade, which negatively regulates the transcription factor Yes-associated protein (YAP).