Neurofibromatosis type 2 (NF2) is an autosomal dominant cancer syndrome that predisposes the development of bilateral vestibular schwannomas. This disease is caused by inactivating mutations of the NF2 tumour-suppressor gene. Mutational analysis of the NF2 gene in typical NF2 patients has demonstrated causative mutations in as many as two-thirds of individuals (Jacoby, L.B. et al., 1997. Am J Hum Genet.). Many studies have documented that the NF2 gene behaves as a typical tumour-suppressor gene in these patients, with first hits detectable in both constitutional and tumour specimens and second hits detectable only in tumours. Kluwe, L. et al. (2005, Genes Chromosomes Cancer) showed that large alterations affecting the NF2 gene account for 27% of the 77 cases in which no intragenic small mutations were found, and for 16% of the total of 134 mutations identified among the 188 NF2 patients screened in the study.
The NF2 gene (17 exons) spans ~95 kb of genomic DNA and is located on 22q12.2, ~30 Mb from the p-telomere. The P044-B3 NF2 probemix contains probes for each of the exons of the NF2 gene. In addition, two probes located in genes upstream of the NF2 gene are included, and one downstream. Eleven reference probes are included detecting different autosomal chromosomal regions.
This SALSA® MLPA® probemix is designed to detect deletions/duplications of one or more sequences in the aforementioned gene in a DNA sample. Heterozygous deletions of recognition sequences should give a 35-50% reduced relative peak height of the amplification product of that probe. Note that a mutation or polymorphism in the sequence detected by a probe can also cause a reduction in relative peak height, even when not located exactly on the ligation site! In addition, some probe signals are more sensitive to sample purity and small changes in experimental conditions. Therefore, deletions and duplications detected by MLPA should always be confirmed by other methods. Not all deletions and duplications detected by MLPA will be pathogenic; users should always verify the latest scientific literature when interpreting their findings. We have no information on what percentage of defects in these genes is caused by deletions/duplications of complete exons. Finally, note that most defects in this gene are expected to be small (point) mutations which will not be detected by this SALSA® MLPA® test.