The SALSA MLPA
Probemix P176 CAPN3 is a research use only (RUO)
assay for the detection of deletions or duplications in the CAPN3
gene, which is associated with limb-girdle muscular dystrophy type 2A (LGMD2A).
Limb-girdle muscular dystrophies (LGMD) are a group of phenotypically and genotypically heterogeneous diseases, characterised by progressive weakness and atrophy of the muscles of the pelvic and shoulder girdle. Mutations of the CAPN3
gene have been associated with limb-girdle muscular dystrophy type 2A (LGMD2A), also called calpainopathy. Patients with LGMD2A have symmetrical and selective involvement of proximal limb-girdle muscles. The disease shows wide intrafamilial and interfamilial clinical variability. The age at onset ranges from 2 to 40 years, but the disease usually first appears in the second or third decade of life, with the development of proximal weakness in the lower limbs. Mutations in CAPN3
result in a cascade of events leading eventually to muscular dystrophy, but the precise underlying mechanisms have yet to be elucidated. However, a defect in proteolytic activity of calpain 3, the protein encoded by CAPN3
, is largely recognised as the main pathogenic cause of LGMD2A.
gene (24 exons) spans ~53 kb of genomic DNA and is located on chromosome 15q15.1, ~40 Mb from the p-telomere. The gene is predominantly expressed in skeletal muscle where it is present in the cytosol as well as in the nucleus. The protein encoded by this gene (calpain 3) belongs to the superfamily of calcium-activated neutral proteases, which are non-lysosomal intracellular cysteine proteases. Calpains respond to Ca2+
signals by cleaving specific proteins, frequently components of signalling cascades, thereby irreversibly modifying their function(s).
More information is available at https://www.ncbi.nlm.nih.gov/books/NBK1313/
The SALSA MLPA Probemix P176-C3 CAPN3 contains 36 MLPA probes with amplification products between 130 and 427 nucleotides (nt). This includes 26 probes for the CAPN3
gene. In addition, 10 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