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SALSA® MLPA® Probemix P405 CMT1 detects copy number variations in the PMP22, MPZ and GJB1 genes.
Contents: 42 MLPA probes, including 15 probes for the common 17p12 deletion/duplication region (PMP22), 7 probes for MPZ, 5 probes for GJB1 and 3 probes for the X-chromosome.
Tissue: genomic DNA isolated from human peripheral whole blood or buccal swabs.
Application: Charcot-Marie-Tooth (CMT) disease type 1, X-linked CMT and hereditary neuropathy with liability to pressure palsies (HNPP).
CE-marked and registered for in vitro diagnostic (IVD) use in selected territories.
The SALSA MLPA Probemix P405 CMT1 is an in vitro diagnostic (IVD) or research use only (RUO) semi-quantitative assay for the detection of deletions or duplications in the human PMP22, MPZ and GJB1 genes in genomic DNA isolated from human peripheral whole blood specimens or buccal swabs. P405 CMT1 is intended to confirm a potential cause for and clinical diagnosis of Charcot-Marie-Tooth disease type 1 (CMT1), X-linked CMT (CMTX) or hereditary neuropathy with liability to pressure palsies (HNPP) and for molecular genetic testing of at-risk family members.
For the full intended purpose, see the product description.
Charcot-Marie-Tooth disease (CMT), with a worldwide incidence of 1 in 2500, is the most common hereditary sensorimotor neuropathy, comprising a group of clinically and genetically heterogeneous peripheral neuropathies. CMT is characterized by progressive distal muscle atrophy and weakness, sensory disturbance, the absence of deep tendon reflexes, and pes cavus deformity of the foot. More than 80 different genes are associated with CMT (http://www.ncbi.nlm.nih.gov/books/NBK1358/). Subtypes related to the genes PMP22, GJB1, MPZ and MFN2 are the most common ones, being responsible for up to 95% of CMT cases with a final diagnosis (Padilha et al. 2020). The disease can be inherited in an autosomal dominant, autosomal recessive or X-linked manner. Table 1 provides an overview of the different genes involved in the CMT subtypes and the probemixes that cover these genes.
The most frequent form, CMT1A, accounts for as much as 50% of all CMT cases. CMT1A is a dominantly inherited, childhood-onset, slowly progressive motor and sensory neuropathy due to a duplication of PMP22 on chromosome 17. CMT1B accounts for an additional ~10% of CMT1 patients. The gene involved in CMT1B is myelin protein zero (MPZ). CMT1A and 1B are clinically indistinguishable; classification is based solely on molecular findings.
X-linked CMT (CMTX) is characterized by moderate to severe motor and sensory neuropathy in affected males and usually mild to no symptoms in carrier females. Subtype CMTX1 accounts for about 90% of X-linked CMT, and is caused by mutations in the gap-junction protein beta 1 (GJB1) gene (https://www.ncbi.nlm.nih.gov/books/NBK1374/).
Hereditary neuropathy with liability to pressure palsies (HNPP) is characterized by repeated focal pressure neuropathies such as carpal tunnel syndrome and peroneal palsy with foot drop. Recovery from acute neuropathy is often complete; when recovery is not complete, the resulting disability is usually mild. Some affected individuals also have signs of a mild to moderate peripheral neuropathy. The prevalence of HNPP is estimated at 7-16 in 100,000. The penetrance is 100% but expressivity is highly variable even within the same family. Approximately 6-23% of individuals diagnosed with HNPP have an asymptomatic affected parent. A contiguous gene deletion of chromosome 17p12 that includes PMP22 is present in approximately 80% of affected individuals; the remaining 20% have a pathogenic variant in PMP22 (https://www.ncbi.nlm.nih.gov/books/NBK1392/).
Probemix* | Genes and coverage | Condition | Remarks |
---|---|---|---|
P033-B4 CMT1 (IVD) |
PMP22: all exons KIF1b: 2 probes |
CMT1A and HNPP CMT2A1 |
PMP22 probes in P033-B4 have the same ligation site as PMP22 probes in P405-B1 except for one exon 1 probe and one exon 4 probe. There is one additional PMP22 exon 5 probe present in P033-B4. |
P405-B1 CMT1 (IVD) |
PMP22: all exons MPZ: all exons GJB1: all exons |
CMT1A and HNPP CMT1B CMTX |
PMP22 probes in P405-B1 have the same ligation sites as PMP22 probes in P033-B4 except for one exon 1 probe and one exon 4 probe. There is one additional PMP22 exon 5 probe present in P033-B4. MPZ probes in P405-B1 have the same ligation sites as MPZ probes in P143-C3. |
P143-C3 MFN2-MPZ (RUO) |
MFN2: all exons MPZ: all exons |
CMT2A CMT1B |
MPZ probes in P143-C3 have the same ligation sites as MPZ probes in P405-B1. |
* IVD: in vitro diagnostic. RUO: research use only.
SALSA MLPA Probemix P405 CMT1 is CE-marked for in vitro diagnostic (IVD) use. This assay has also been registered for IVD use in Colombia and Israel.
This assay is for research use only (RUO) in all other territories.
A general SALSA MLPA Reagent Kit is required for MLPA experiments (to be ordered separately).
Inclusion of a positive sample is usually not required, but can be useful for the analysis of your experiments. MRC Holland has very limited access to positive samples and cannot supply such samples. We recommend using positive samples from your own collection. Alternatively, you can use positive samples from an online biorepository, such as the Coriell Institute.
See this support article for commercially available positive samples that have been tested with this product.