The SALSA MLPA
probemixes P081 NF1 mix 1 and P082 NF1 mix 2 are an in vitro diagnostic (IVD)1
or a research use only (RUO) assay for the detection of deletions or duplications in the human NF1
gene in order to confirm a clinical diagnosis of Neurofibromatosis type 1. This assay is for use with human DNA derived from peripheral blood and not for use with DNA extracted from formalin-fixed paraffin embedded or fresh tumour materials.
Deletions or duplications detected with the P081 NF1 mix 1 and P082 NF1 mix 2 probemixes should be verified by another technique. In particular, deletions or duplications detected by only a single probe always require validation by another method. Most defects in the NF1
gene are point mutations, which will not be detected by MLPA. It is therefore recommended to use these SALSA MLPA probemixes in combination with sequence analysis of the NF1
gene. These probemixes are not intended to be used as standalone assays for clinical decisions. The results of this test should be interpreted by a clinical molecular geneticist or equivalent.
Please note that these probemixes are for In Vitro Diagnostic (IVD) use in the countries specified at the end of this product description. In all other countries, the product is for Research Use Only (RUO).
Neurofibromatosis is an autosomal dominant disorder characterised particularly by café-au-lait spots and fibromatous tumours of the skin. Neurofibromatosis type 1 is caused by loss-of-function mutations in the NF1
gene on 17q11.2. Neurofibromatosis type 2 is caused by defects in the NF2
gene on chromosome 22q12.2, for which the P044 NF2 MLPA probemix (RUO) can be used.
Estimated birth incidence of Neurofibromatosis type 1 is 1 in 3000, with about half of the NF1 cases caused by de novo
sporadic mutations. De novo
sporadic mutations may also be the result of germline mosaicism in apparently unaffected parents.
Deletions of part of the NF1
gene as well as deletions and duplications of the complete NF1
gene have been described. Relatively common (5-10% of NF1 cases) is a deletion of a 1.4 Mb chromosomal region harbouring multiple genes, including the NF1
gene. The phenotype of this 17q11.2 microdeletion is usually much more severe than most other NF1 cases and may include developmental delay. Next to the 1.4 Mb deletion described above, a 1.2 Mb microdeletion and nonrecurrent atypical microdeletions of different sizes have been reported. The P122 NF1 area MLPA probemix (RUO) can be used to determine the extent of the deletion as it contains many probes for other genes in the frequently deleted 1.4 Mb region.
More information is available on https://www.ncbi.nlm.nih.gov/books/NBK1109/
P081-D1 and P082-C2 probemix content:
The P081 and P082 probemixes together contain one probe for each exon, three probes for exon 1, one probe for intron 1, and two probes for the exons 15, 21, 23, 51 and 58 of the NF1
gene. Additionally, these probemixes contain one upstream and one downstream probe and two probes for the OMG
gene, located within intron 36 of the NF1
The P081-D1 probemix contains 46 MLPA probes with amplification products between 130 and 463 nt in length, including 11 reference probes. The P082-C2 probemix contains 44 MLPA probes with amplification products between 130 and 483 nt in length, nine of which are reference probes. The identity of the genes detected by the reference probes is available online (www.mlpa.com
Both these probemixes contain nine quality control fragments generating amplification products between 64 and 105 nt: four DNA Quantity Fragments (Q-fragments), two DNA Denaturation Fragments (D-fragments), one benchmark fragment, one chromosome X and one chromosome Y-specific fragment. More information on how to interpret observations on these control fragments can be found in the MLPA General Protocol and online at www.mlpa.com