The SALSA MLPA Probemixes P034 DMD-1 and P035 DMD-2 are in vitro diagnostic (IVD)1
or a research use only (RUO) semi-quantitative assays2
for the detection of deletions or duplications in the DMD
gene in genomic DNA isolated from human peripheral whole blood specimens, (un)cultured amniotic fluid obtained in week 16 of the pregnancy or later and free from blood contamination, (un)cultured chorionic villi free from maternal contamination, or fetal blood. P034 DMD-1 and P035 DMD-2 are intended to confirm a potential cause for and clinical diagnosis of Duchenne muscular dystrophy or Becker muscular dystrophy, for molecular genetic testing of at-risk family members, and for carrier screening.
Copy number variations (CNVs) detected with P034 DMD-1 and P035 DMD-2 should be confirmed with a different technique. In particular, CNVs detected by only a single probe always require confirmation by another method. Most defects in the DMD
gene are CNVs, however point mutations can occur which will not be detected by MLPA. It is therefore recommended to use this assay in combination with sequence analysis.
Assay results are intended to be used in conjunction with other clinical and diagnostic findings, consistent with professional standards of practice, including confirmation by alternative methods, parental evaluation, clinical genetic evaluation, and counselling, as appropriate. The results of this test should be interpreted by a clinical molecular geneticist or equivalent.
These devices are not intended to be used for standalone diagnostic purposes, pre-implantation, or for the detection of, or screening for, acquired or somatic genetic aberrations.
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).
To be used in combination with a SALSA MLPA Reagent Kit and Coffalyser.Net analysis software.
Germline defects in the dystrophin (DMD)
gene are the most frequent cause of Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD). DMD and BMD occur almost exclusively in males as they are inherited in an X-linked recessive manner. DMD usually has an early onset in childhood with delayed milestones, which include delays in sitting and standing independently. Proximal weakness causes a waddling gait and difficulty in climbing. DMD is rapidly progressive, with affected children being wheelchair dependent by the age of 13. Respiratory complications and cardiomyopathy occur in individuals with DMD after the age of 18 and a few survive beyond the third decade of life. In contrast, BMD has a slower rate of progression and patients on average survive until their mid-40s. More information on both conditions is available at http://www.ncbi.nlm.nih.gov/books/NBK1119/.
Deletions and duplications of complete exons in the DMD
gene are the most frequent cause of DMD/BMD and are usually missed by standard sequence analysis. Most of these deletions and duplications can be detected by the MLPA technique and hence MLPA complements sequence analysis of the DMD
gene. Approximately 60-70% of mutations in patients with DMD and BMD are deletions. Duplications in the DMD gene are found in 5-15% of DMD patients and 20% of BMD patients, respectively (Duan et al. 2021). Best practice guidelines on molecular diagnostics in Duchenne/Becker muscular dystrophies have been published (Abbs et al. 2010, Fratter et al. 2020).
The SALSA MLPA Probemix P034-B2 DMD-1 contains 49 MLPA probes with amplification products between 130 and 500 nucleotides (nt). The SALSA MLPA Probemix P035-B1 DMD-2 contains 48 MLPA probes with amplification products between 130 and 500 nt. The P034-B2 and P035-B1 probemixes together contain one probe for each of the 79 DMD
exons included in transcript variant Dp427m. In addition, one probe is present in P035-B1 for the alternative promoter/exon 1 found in transcript variant Dp427c. Performing two MLPA reactions, one with P034-B2 and one with P035-B1, is thus sufficient to investigate the copy number of all DMD
exons. In addition, P034-B2 and P035-B1 contain nine and eight reference probes, respectively, which detect locations on the X-chromosome. 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