scholarly journals Genotype–Phenotype Correlations in Duchenne and Becker Muscular Dystrophy Patients from the Canadian Neuromuscular Disease Registry

2020 ◽  
Vol 10 (4) ◽  
pp. 241
Author(s):  
Kenji Rowel Q. Lim ◽  
Quynh Nguyen ◽  
Toshifumi Yokota
Keyword(s):  
Muscular Dystrophy ◽  
Neuromuscular Disease ◽  
Becker Muscular Dystrophy ◽  
Neuromuscular Disorder ◽  
Test Results ◽  
Disease Registry ◽  
Reading Frame ◽  
Negative Results ◽  
Genetic Test Results ◽  
Dmd Gene

Duchenne muscular dystrophy (DMD) is a fatal neuromuscular disorder generally caused by out-of-frame mutations in the DMD gene. In contrast, in-frame mutations usually give rise to the milder Becker muscular dystrophy (BMD). However, this reading frame rule does not always hold true. Therefore, an understanding of the relationships between genotype and phenotype is important for informing diagnosis and disease management, as well as the development of genetic therapies. Here, we evaluated genotype–phenotype correlations in DMD and BMD patients enrolled in the Canadian Neuromuscular Disease Registry from 2012 to 2019. Data from 342 DMD and 60 BMD patients with genetic test results were analyzed. The majority of patients had deletions (71%), followed by small mutations (17%) and duplications (10%); 2% had negative results. Two deletion hotspots were identified, exons 3–20 and exons 45–55, harboring 86% of deletions. Exceptions to the reading frame rule were found in 13% of patients with deletions. Surprisingly, C-terminal domain mutations were associated with decreased wheelchair use and increased forced vital capacity. Dp116 and Dp71 mutations were also linked with decreased wheelchair use, while Dp140 mutations significantly predicted cardiomyopathy. Finally, we found that 12.3% and 7% of DMD patients in the registry could be treated with FDA-approved exon 51- and 53-skipping therapies, respectively.

scholarly journals CRISPR-Generated Animal Models of Duchenne Muscular Dystrophy

Genes ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 342 ◽  
Author(s):  
Kenji Rowel Q. Lim ◽  
Quynh Nguyen ◽  
Kasia Dzierlega ◽  
Yiqing Huang ◽  
Toshifumi Yokota
Keyword(s):  
Duchenne Muscular Dystrophy ◽  
Muscular Dystrophy ◽  
Animal Models ◽  
Mechanical Stress ◽  
Muscle Cell ◽  
Neuromuscular Disorder ◽  
Reading Frame ◽  
Advantages And Disadvantages ◽  
Short Palindromic Repeat ◽  
Dmd Gene

Duchenne muscular dystrophy (DMD) is a fatal X-linked recessive neuromuscular disorder most commonly caused by mutations disrupting the reading frame of the dystrophin (DMD) gene. DMD codes for dystrophin, which is critical for maintaining the integrity of muscle cell membranes. Without dystrophin, muscle cells receive heightened mechanical stress, becoming more susceptible to damage. An active body of research continues to explore therapeutic treatments for DMD as well as to further our understanding of the disease. These efforts rely on having reliable animal models that accurately recapitulate disease presentation in humans. While current animal models of DMD have served this purpose well to some extent, each has its own limitations. To help overcome this, clustered regularly interspaced short palindromic repeat (CRISPR)-based technology has been extremely useful in creating novel animal models for DMD. This review focuses on animal models developed for DMD that have been created using CRISPR, their advantages and disadvantages as well as their applications in the DMD field.

scholarly journals CRISPR-Generated Animal Models of Duchenne Muscular Dystrophy

2020 ◽  
Author(s):  
Kenji Rowel Q. Lim ◽  
Quynh Nguyen ◽  
Kasia Dzierlega ◽  
Yiqing Huang ◽  
Toshifumi Yokota
Keyword(s):  
Duchenne Muscular Dystrophy ◽  
Muscular Dystrophy ◽  
Animal Models ◽  
Mechanical Stress ◽  
Muscle Cell ◽  
Muscle Cells ◽  
Neuromuscular Disorder ◽  
Reading Frame ◽  
Advantages And Disadvantages ◽  
Dmd Gene

Duchenne muscular dystrophy (DMD) is a fatal X-linked recessive neuromuscular disorder most commonly caused by mutations disrupting the reading frame of the dystrophin (DMD) gene. DMD codes for dystrophin, which is critical for maintaining the integrity of muscle cell membranes. Without dystrophin, muscle cells receive heightened mechanical stress, becoming more susceptible to damage. An active body of research continues to explore therapeutic treatments for DMD as well as to further our understanding of the disease. These efforts rely on having reliable animal models that accurately recapitulate disease presentation in humans. While current animal models of DMD have served this purpose quite well, each comes with their own limitations. To help overcome this, clustered regularly interspaced short palindromic repeats (CRISPR)-based technology has been extremely useful in creating novel animal models for DMD. This review focuses on animal models developed for DMD that have been created using CRISPR, their advantages and disadvantages as well as their applications in the DMD field.

scholarly journals Mutation-Based Therapeutic Strategies for Duchenne Muscular Dystrophy: From Genetic Diagnosis to Therapy

2019 ◽  
Vol 9 (1) ◽  
pp. 16 ◽  
Author(s):  
Akinori Nakamura
Keyword(s):  
Muscular Dystrophy ◽  
Single Gene ◽  
Genetic Diagnosis ◽  
Exon Skipping ◽  
Becker Muscular Dystrophy ◽  
Therapeutic Strategies ◽  
Severe Phenotype ◽  
Reading Frame ◽  
Dystrophin Expression ◽  
Dmd Gene

Duchenne and Becker muscular dystrophy (DMD/BMD) are X-linked muscle disorders caused by mutations of the DMD gene, which encodes the subsarcolemmal protein dystrophin. In DMD, dystrophin is not expressed due to a disruption in the reading frame of the DMD gene, resulting in a severe phenotype. Becker muscular dystrophy exhibits a milder phenotype, having mutations that maintain the reading frame and allow for the production of truncated dystrophin. To date, various therapeutic approaches for DMD have been extensively developed. However, the pathomechanism is quite complex despite it being a single gene disorder, and dystrophin is expressed not only in a large amount of skeletal muscle but also in cardiac, vascular, intestinal smooth muscle, and nervous system tissue. Thus, the most appropriate therapy would be complementation or restoration of dystrophin expression, such as gene therapy using viral vectors, readthrough therapy, or exon skipping therapy. Among them, exon skipping therapy with antisense oligonucleotides can restore the reading frame and yield the conversion of a severe phenotype to one that is mild. In this paper, I present the significance of molecular diagnosis and the development of mutation-based therapeutic strategies to complement or restore dystrophin expression.

scholarly journals Becker muscular dystrophy associated with sarcomeric hypertrophic cardiomyopathy in a paediatric patient: a case report

2019 ◽  
Vol 3 (3) ◽  
Author(s):  
Paola Dolader ◽  
Ella Field ◽  
Anna Sarkozy ◽  
Juan Pablo Kaski
Keyword(s):  
Hypertrophic Cardiomyopathy ◽  
Muscular Dystrophy ◽  
Neuromuscular Disorders ◽  
Elevated Serum ◽  
Becker Muscular Dystrophy ◽  
Neuromuscular Disorder ◽  
Chain Gene ◽  
Septal Hypertrophy ◽  
History Of ◽  
Myocardial Involvement

Abstract Background  Becker muscular dystrophy (BMD) is a neuromuscular disorder associated with myocardial involvement. The most frequent presentation is dilated cardiomyopathy. There have been isolated reports of hypertrophic cardiomyopathy (HCM) in association with BMD, but it is unclear whether these patients had an additional aetiology. Case summary  A 10-year-old boy was diagnosed with BMD having presented with a history of muscular pain during exercise and elevated serum creatine kinase levels. A cardiac screening was arranged and the echocardiogram confirmed an asymmetric septal hypertrophy. Given the unusual finding of HCM in this patient with BMD, we performed genetic testing for HCM-causing mutations and identified a likely pathogenic variant in heterozygosis in the beta-myosin heavy chain gene. Discussion  This case highlights the importance of considering additional aetiologies of cardiac disease in the presence of infrequent phenotypic expressions in neuromuscular disorders.

scholarly journals Analysis of Dystrophin Gene Deletions by Multiplex PCR in Moroccan Patients

2002 ◽  
Vol 2 (3) ◽  
pp. 158-160 ◽  
Author(s):  
Aziza Sbiti ◽  
Fatiha El Kerch ◽  
Abdelaziz Sefiani
Keyword(s):  
Hot Spots ◽  
Neuromuscular Disease ◽  
Multiplex Polymerase Chain Reaction ◽  
Dystrophin Gene ◽  
Becker Muscular Dystrophy ◽  
Chain Reaction ◽  
Gene Deletions ◽  
Polymerase Chain ◽  
Dmd Gene ◽  
Moroccan Patients

Duchenne and Becker muscular dystrophy (DMD and BMD) are X-linked diseases resulting from a defect in the dystrophin gene located on Xp21. DMD is the most frequent neuromuscular disease in humans (1/3500 male newborn). Deletions in the dystrophin gene represent 65% of mutations in DMD/BMD patients. We have analyzed DNA from 72 Moroccan patients with DMD/BMD using the multiplex polymerase chain reaction (PCR) to screen for exon deletions within the dystrophin gene, and to estimate the frequency of these abnormalities. We found dystrophin gene deletions in 37 cases. Therefore the frequency in Moroccan DMD/BMD patients is about 51.3%. All deletions were clustered in the two known hot-spots regions, and in 81% of cases deletions were detected in the region from exon 43 to exon 52. These findings are comparable to those reported in other studies. It is important to note that in our population, we can first search for deletions of DMD gene in the most frequently deleted exons determined by this study. This may facilitate the molecular diagnosis of DMD and BMD in our country.

Dystrophinopathy in a Family Due to a Rare Nonsense Mutation Causing Predominant Behavioral Phenotype

2019 ◽  
Vol 18 (04) ◽  
pp. 210-213
Author(s):  
Yohei Harada ◽  
Seth T. Sorensen ◽  
Akilandeswari Aravindhan ◽  
Vikki Stefans ◽  
Aravindhan Veerapandiyan
Keyword(s):  
Intellectual Disability ◽  
Muscular Dystrophy ◽  
Behavioral Problems ◽  
Nonsense Mutation ◽  
Neuromuscular Disorders ◽  
Elevated Serum ◽  
Becker Muscular Dystrophy ◽  
Genetic Changes ◽  
Dmd Gene ◽  
Neurobehavioral Deficits

AbstractDystrophinopathies are a group of X-linked neuromuscular disorders resulting from mutations in DMD gene that encodes dystrophin. The clinical spectrum includes Duchenne muscular dystrophy, Becker muscular dystrophy, X-linked cardiomyopathy, and intellectual disability without involvement of skeletal muscle. Cognitive and behavioral problems are commonly seen among patients with dystrophinopathy. DMD gene is the largest human gene, consisting of 79 exons that produce dystrophin protein. Patients with genetic changes involving shorter dystrophin isoforms such as Dp140 and Dp71 are suggested to have higher rates of intellectual disability, attention-deficit/hyperactivity disorder, and other neuropsychiatric comorbidities. We describe three brothers who presented with prominent neurobehavioral deficits of varying degree, mild proximal weakness, and elevated serum creatine kinase due to a rare nonsense mutation, c.1702C > T; p.Gln568X, in exon 14 of DMD gene. Further studies are needed to better understand the effects of this rare mutation.

scholarly journals Clinicopathologic and molecular profiles of Duchenne and Becker muscular dystrophy

2019 ◽  
Vol 59 (5) ◽  
pp. 257-64
Author(s):  
Ery Kus Dwianingsih ◽  
Meydita Fuzia Putri Insani ◽  
Linda Pratiwi ◽  
Irianiwati Widodo ◽  
Rusdy Ghazali Malueka
Keyword(s):  
Muscular Dystrophy ◽  
Muscle Biopsy ◽  
Clinical Manifestations ◽  
Becker Muscular Dystrophy ◽  
High Serum ◽  
Molecular Profile ◽  
Molecular Profiles ◽  
Weak Expression ◽  
Dmd Gene ◽  
Histopathological Grading

Background Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD) are allelic X-linked recessive diseases caused by mutations in the dystrophin (DMD) gene. To our knowledge, molecular analysis to differentiate between DMD and BMD has never been performed in Indonesia. Objective To elaborate the clinicopathologic and molecular profiles of DMD/BMD patients in Yogyakarta, Indonesia. Methods Eighteen muscle biopsy specimens of patients clinically suspected to have DMD/BMD were collected. Possible associations of clinical manifestations, histopathological grading, and immunohistochemistry (IHC) results were analyzed. Polymerase chain reaction (PCR) was performed to identify mutations in exon 52. Results. Positive Gower’s sign and high serum creatine kinase (CK) were observed in most patients. The IHC of dystrophin in two female patients suggested that they were manifesting carriers. Of the 16 male patients, 12 showed negative IHC staining, indicating DMD, while 4 patients demonstrated weak expression of dystrophin, indicating BMD. There was a significant association between high CK level and IHC results (P=0.005), indicating higher CK level in DMD patients. Histopathological grading of muscle biopsy was significantly associated with diagnosis of DMD/BMD using IHC (P=0.01), showing more severe tissue damage in DMD patients. None of the subjects had the single exon 52 deletion. Conclusion This is the first report of a clinicopathologic and molecular profile of DMD/BMD in an Indonesian population. Serum CK level and histopathological grading of muscle biopsy are useful in distinguishing DMD from BMD in settings where an IHC assay is not available.

Germinal Mosaicism in a Sample of Families with Duchenne/Becker Muscular Dystrophy with Partial Deletions in the DMD Gene

2014 ◽  
Vol 18 (2) ◽  
pp. 93-97 ◽  
Author(s):  
Cesárea Bermúdez-López ◽  
Benilde García-de Teresa ◽  
Ariadna González-del Angel ◽  
Miguel Angel Alcántara-Ortigoza
Keyword(s):  
Muscular Dystrophy ◽  
Becker Muscular Dystrophy ◽  
Dmd Gene ◽  
Germinal Mosaicism

scholarly journals Repurposing Pathogenic Variants of DMD Gene and its Isoforms for DMD Exon Skipping Intervention

2020 ◽  
Vol 20 (7) ◽  
pp. 519-530 ◽  
Author(s):  
Rahul Tyagi ◽  
Sumit Kumar ◽  
Ashwin Dalal ◽  
Faruq Mohammed ◽  
Manju Mohanty ◽  
...  
Keyword(s):  
Exon Skipping ◽  
Population Based ◽  
Neuromuscular Disorder ◽  
Copy Number Variations ◽  
Reading Frame ◽  
The North ◽  
Pathogenic Variants ◽  
Mutation Database ◽  
Dmd Gene ◽  
Dependent Probe

Background: Duchenne Muscular Dystrophy (DMD) is a progressive, fatal neuromuscular disorder caused by mutations in the DMD gene. Emerging antisense oligomer based exon skipping therapy provides hope for the restoration of the reading frame. Objectives: Population-based DMD mutation database may enable exon skipping to be used for the benefit of patients. Hence, we planned this study to identify DMD gene variants in North Indian DMD cases. Methods: A total of 100 DMD cases were recruited and Multiplex ligation-dependent probe amplification (MLPA) analysis was performed to obtain the deletion and duplication profile. Results: Copy number variations (deletion/duplication) were found in 80.85% of unrelated DMD cases. Sixty-eight percent of cases were found to have variations in the distal hotspot region (Exon 45- 55) of the DMD gene. Exon 44/45 variations were found to be the most prominent among single exon variations, whereas exon 49/50 was found to be the most frequently mutated locations in single/ multiple exon variations. As per Leiden databases, 86.84% cases harboured out-of-frame mutations. Domain wise investigation revealed that 68% of mutations were localized in the region of spectrin repeats. Dp140 isoform was predicted to be absent in 62/76 (81.57%) cases. A total of 45/80 (56.25 %) and 23/80 (28.70%) DMD subjects were predicted to be amenable to exon 51 and exon 45 skipping trials, respectively. Conclusion: A major proportion of DMD subjects (80%) could be diagnosed by the MLPA technique. The data generated from our study may be beneficial for strengthening of mutation database in the North Indian population.

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