A novel mutation of the FAT2 gene in spinal meningioma

Meningiomas may be classified as neurofibromin 2 (NF2)-associated and non-NF2 meningiomas depending on the presence or absence of molecular alterations in the NF2 gene. One of the characteristic histological features of meningiomas is the whorl formation of neoplastic arachnoid cells. NF2 is a human homolog of the Drosophila gene, Merlin (Mer). In humans, NF2 is the gene responsible for the disease neurofibromatosis type II, which results in the development of brain tumors, including acoustic neurinoma and meningioma. The present study aimed to investigate the molecular pathogenesis of spinal meningioma. It was hypothesized that the whorl formation of meningiomas may occur as a result of a disturbance in the planar cell polarity (PCP) of arachnoid cells, thus, genes understood to govern PCP signaling were analyzed for alterations. Whole exome sequencing followed by Sanger sequencing validation was performed for the analysis of spinal meningioma tissue obtained from a 42-year-old Japanese female. The sequencing identified a nonsynonymous mutation of c.3597G>C, resulting in p.Q1199H, in the FAT atypical cadherin 2 (FAT2) gene. FAT2 is homologous to the Drosophila Fat (Ft) gene, which belongs to the cadherin superfamily. Drosophila Fat is involved in PCP, tumor suppression and Hippo (Hpo) signaling, which is associated with Mer. Taken together, the results of the present study concluded that human FAT2 may function as a key molecule that governs not only PCP, but also NF2-Hpo signaling in arachnoid cells; thus, a mutation in this gene may result in spinal meningioma.