Molecular pathogenesis of the schwannomatosis genes and genetic testing strategies.

The three major schwannomatosis genes, NF2, LZTR1 and SMARCB1, are all located within approximately 9 megabases on chromosome 22 and cause three genetically distinct conditions with significant clinical phenotypic overlap. All forms of schwannomatosis predispose to the development of multiple schwannomas, but display differences in tumour location and long-term prognosis. In addition, high levels of mosaic disease can complicate clinical diagnosis. Genetic diagnosis can be critical for distinguishing between the three conditions to optimise clinical management, especially in cases of mosaic disease. This review summarises the distinctions between the clinical and genetic characteristics of each form of schwannomatosis and discusses the genetic analytic tools that are typically used to detect the variants found in these conditions.