General information
The SALSA MLPA Probemix P353 CMT4 is a research use only (RUO) assay for the detection of deletions or duplications in the GDAP1, MTMR2, SBF2, SH3TC2, EGR2, and PRX genes, which are associated with Charcot-Marie-Tooth neuropathy type 4 (CMT4). In addition, this probemix contains probes for the NEFL gene, which is involved in CMT type 1F and 2E.

CMT4 is a group of progressive motor and sensory axonal and demyelinating neuropathies, which is inherited in an autosomal recessive manner. It is characterised by distal muscle weakness and atrophy that is associated with sensory loss and foot deformity. CMT4 is classified into 9 different subtypes (CMT4A to CMT4J). This probemix contains a selection of six genes that are correlated with one of the different subtypes.

The GDAP1 gene (6 exons) spans ~17 kb of genomic DNA and is located on 8q21.11, 75 Mb from the p-telomere. The GDAP1 gene encodes a member of the ganglioside-induced differentiation associated protein which is abundantly expressed in brain tissue. CMT4A and intermediated forms of the disorder are caused by mutations in the GDAP1 gene. This probemix contains one probe for each exon, with the exception of exon 3.

The MTMR2 gene (15 exons) spans ~91 kb of genomic DNA and is located on 11q21, 95 Mb from the p-telomere. The MTMR2 gene encodes a protein that belongs to the myotubularin family. CMT4B1 is caused by mutations in the MTMR2 gene. This probemix contains six probes for this gene.

The SBF2 gene (40 exons) spans ~515 kb of genomic DNA and is located on 11p15.4, 10 Mb from the p-telomere. The SBF2 gene encodes a member of the myotubularin-related protein family. Defects in the SBF2 gene are the cause of CMT4B2. This probemix contains eight probes for this gene.

The SH3TC2 gene (17 exons) spans ~81 kb of genomic DNA and is located on 5q33.1, 148 Mb from the p-telomere. The gene encodes the SH3TC2 protein which is expressed in Schwann cells of the peripheral nerves. Defects in the SH3TC2 gene are the cause of CMT4C. This probemix contains seven probes for this gene.

The EGR2 gene (4 exons) spans ~4 kb of genomic DNA and is located on 10q21.2, 64 Mb from the p-telomere. The gene encodes a member of the early growth response family of proteins, and functions as a transcription factor. Defects in the EGR2 gene are the cause of CMT4E and CMT1D. This probemix contains one probe for each exon, with the exception of exon 3.

The PRX gene (7 exons) spans ~20 kb of genomic DNA and is located on 19q13.2, 46 Mb from the p-telomere. The gene encodes for 2 isoforms, L- and S-periaxin, which are structural proteins required for the maintenance of myelin. CMT4F is caused by mutations in the PRX gene. This probemix contains one probe for each exon of this gene.

This probemix furthermore contains probes for all four exons of the NEFL gene. The NEFL gene spans ~6 kb of genomic DNA and is located on 8p21.2, 25 Mb from the p-telomere. The gene encodes the light chain neurofilament protein. Defects in the NEFL gene are the cause of CMT1F and CMT2E.

More information is available at https://www.ncbi.nlm.nih.gov/books/NBK1468/.
This SALSA MLPA probemix is not CE/FDA registered for use in diagnostic procedures. Purchase of this product includes a limited license for research purposes.

Gene structure and transcript variants:
Entrez Gene shows transcript variants of each gene: http://www.ncbi.nlm.nih.gov/sites/entrez?db=gene
For NM_ mRNA reference sequences: http://www.ncbi.nlm.nih.gov/sites/entrez?db=nucleotide
Locus Reference Genomic (LRG) database: http://www.lrg-sequence.org/

Probemix content
The SALSA MLPA Probemix P353-B1 CMT4 contains 49 MLPA probes with amplification products between 131 and 483 nucleotides (nt). This includes 40 probes that target all exons of the NEFL and PRX genes and several exons of the GDAP1, MTMR2, SBF2, SH3TC2, and EGR2 genes. In addition, nine reference probes are included that detect autosomal chromosomal locations. Complete probe sequences and the identity of the genes detected by the reference probes are available online (www.mrcholland.com).
This probemix contains 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, and 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.mrcholland.com.