Do NGS-based techniques represent a first-line testing in suspected Duchenne muscular dystrophy?

فونت Myopathies are a disorder of skeletal muscle with proximal muscle weakness as a common symptom ۱. The mutation in the dystrophin gene can lead to a severe form, Duchenne muscular dystrophy (DMD; OMIM: ۳۱۰۲۰۰),and a milder form, Becker muscular dystrophy (BMD; OMIM: ۳۰۰۳۷۶),which are the most common types of dystrophies ۲. Duchenne muscular dystrophy is one of the most common progressive neuromuscular diseases with inherited sex-linked inheritance that generally affects only boys with an estimated incidence of ۱/۳۶۰۰ male births worldwide, and females who are carriers have milder symptoms ADDIN EN.CITE Falzarano۲۰۱۵۳۳۳۱۷Falzarano, Maria SofiaScotton, ChiaraPassarelli, ChiaraFerlini, AlessandraMoleculesMolecules۱۸۱۶۸-۱۸۱۸۴۲۰۱۰۲۰۱۵۳. The dystrophin gene is the largest described human gene, located at Xp۲۱.۲ and comprises ۷۹ exons with more than ۲.۵ Mb span of DNA ۴. This gene produces a protein located primarily in skeletal and cardiac muscle and small amounts in the brain۵. DMD is caused by different mutations, containing a deletion of one or more exons is responsible for approximately ۶۰–۷۰ % of mutations, duplications are responsible for ۵–۱۰ % of cases, Small mutations (small deletions or insertions, missense, and nonsense mutations and splicing mutations) are almost responsible for ۲۵–۳۵ % of mutations, and approximately ۲% of the remaining mutations are due to intronic rearrangements ۶. In healthy muscle, Dystrophin protein plays an essential role in the stabilization of muscle fiber membranes and the connection of the extracellular basement membrane with the intracellular cytoskeleton ۷. The absence of dystrophin leads to an increase in the cell membrane’s permeability, which allows intracellular creatine kinase to enter the serum, along with intracellular calcium intake. Persistent inflammation is initially associated with necrosis and hypertrophy, followed by progressive loss of regeneration and muscle degeneration, which is characteristic of DMD ۸. Duchenne muscular dystrophy is a rapidly progressing disease, and all patients usually need to use a wheelchair by age ۱۰; DMD patients develop a severe type of cardiomyopathy, which generally appears at age ۱۰, and Most of them die due to heart diseases and respiratory disorders ۹, ۱۰. The average life expectancy in patients with Duchenne muscular dystrophy is between ۲۰ and ۳۰ years ۱۱. As reported in studies, small mutations in the dystrophin gene are one of the causes of Duchenne muscular dystrophy, which is costly and inefficient to detect by traditional sequencing methods such as Sanger. The MLPA method is also used to identify large mutations [۱۲]. In this study, we used the NGS technique to sequence and identify micro duplications in the dystrophin gene.The diagnosis of DMD is dependent on the physical examination of the patient, such as the outcome of muscle biopsy, increased creatine kinase (CK) enzyme, electromyography (EMG), and molecular tests for dystrophin gene analysis.

کلیدواژه ها:

DMD ، next-generation ، molecular diagnosis sequencing