General information: The SALSA MLPA
Probemix P309 MTM1 is a
research use only (RUO) assay for the detection of deletions or duplications in the
MTM1 and
MTMR1 genes, which are associated with X-linked myotubular myopathy.
X-linked myotubular myopathy, also known as myotubular myopathy, is characterised by progressive muscle weakness (myopathy) and decreased muscle tone (hypotonia) that can range from mild to severe. Defects in the
MTM1 gene on chromosome Xq28 are the main cause of X-linked myotubular myopathy. The protein encoded by this gene is myotubularin, a dual-specificity phosphoinositide-3-phosphatase. The
MTMR1 gene is located at very short distance from the
MTM1 gene. The two genes share a similar genomic structure, suggesting that they originate from an intrachromosomal gene duplication. Deletions including both (or part of)
MTM1 and
MTMR1 have been described. However, deletion of the
MTMR1 gene has little clinical significance during early postnatal life (Zanoteli et al. 2005).
The
MTM1 gene (15 exons) spans ~105 kb of genomic DNA and is located on chromosome Xq28, ~150 Mb from the p-telomere. The
MTMR1 gene (16 exons) spans ~72 kb of genomic DNA and is also located on chromosome Xq28, 20 kb telomeric to the
MTM1 gene.
More information is available at
https://www.ncbi.nlm.nih.gov/books/NBK1432/.
Probemix content: The SALSA MLPA Probemix P309-B2 MTM1 contains 35 MLPA probes with amplification products between 130 and 418 nucleotides (nt). This includes 14 probes for the
MTM1 gene, one probe for each exon with the exception of exon 12, and seven probes for the
MTMR1 gene. Furthermore, this probemix also contains three flanking probes located elsewhere on Xq28. In addition, 11 reference probes are included that detect locations on the X-chromosome. Complete probe sequences and the identity of the genes detected by the reference probes are available online (
www.mlpa.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.mlpa.com.