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Abstract Introduction Mutations in the 79 exons of the dystrophin gene result in muscle wasting and weakness of varying clinical severity, ranging from severe/typical Duchenne muscular dystrophy (DMD) to intermediate DMD and mild Becker muscular dystrophy (BMD), depending on the frameshift of the mutation. We previously reported that males with DMD have progressively declining appendicular lean mass (ALM) and ALM index (ALMI) with age and worsening functional motor ability compared with healthy controls. These indices have not been studied in patients with intermediate DMD and BMD phenotypes and across DMD genotypes. In this study, we compared age‐related trajectories of ALM and ALMI of patients who had (1) BMD without functional mobility deficits with patients who had DMD at different stages of disease and healthy controls; (2) a DMD intermediate phenotype with patients who had a typical DMD phenotype; and (3) DMD categorized by genotype. Methods We conducted a retrospective review of ALM and ALMI data from 499 patients (ages 5–23 years) with DMD (466 typical and 33 intermediate) and 46 patients (ages 5–21 years) with BMD (without functional mobility deficits and functional mobility score of 1). Patients were grouped according to age reflecting disease stage (ages 5 to

Developmental disorders associated with Becker muscular dystrophy (BMD), possibly resulting from a lack of dystrophin in the brain, have been reported, but their importance is not fully understood. We report a case of a BMD patient who had been socially withdrawn due to mental retardation and autism spectrum disorder and could not receive appropriate medical services, resulting in delayed detection of severe cardiomyopathy and embolic strokes which developed as complications of BMD. Case report: The case is a 41-year-old male. In elementary school, he was the slowest runner in his class and had poor grades. He started missing school due to bullying in junior high school and had been socially withdrawn for 24 years. He developed difficulty walking due to progressive muscle weakness in the extremities and lost ambulation at age 36. At age 41, he was referred to our hospital by public health support services to address his social withdrawal. Muscle biopsy led to the diagnosis of BMD. Psychological examination revealed mild mental retardation and autism spectrum disorder, which may have resulted in social isolation. He had severe cardiomyopathy and asymptomatic cerebral infarction due to heart failure. In BMD patients, developmental disorders can potentially hinder access to appropriate medical treatment. BMD is an important differential diagnosis for physically disabled children with developmental disorders. Early intellectual and psychological interventions and evaluation of complications are important for improving patient prognosis and quality of life. [ABSTRACT FROM AUTHOR]

Muscular Dystrophies (MDs) are a group of inherited diseases and heterogeneous in nature. To date, 40 different genes have been reported for the occurrence and/or progression of MDs. This study was conducted to demonstrate the application of next-generation sequencing (NGS) in developing a time-saving and cost-effective diagnostic method to detect single nucleotide variants (SNVs) and copy number variants (CNVs) in a single test. A total of 123 cases clinically suspected of MD were enrolled in this study. Amplicon panel-based diagnosis was carried out for 102 (DMD/BMD) cases and the results were further screened using multiplex ligation-dependent probe amplification (MLPA). Whilst in the case of LGMD (N = 19) and UMD (N = 2), only NGS panel-based analysis was carried out. We identified the large deletions in 74.50% (76/102) of the cases screened with query DMD or BMD. Further, the large deletion in CAPN3 gene (N = 3) and known SNV mutations (N = 4) were identified in LGMD patients. Together, the total diagnosis rate for this amplicon panel was 70.73% (87/123) which demonstrated the utility of panel-based diagnosis for high throughput, affordable, and time-saving diagnostic strategy. Collectively, present study demonstrates that the panel based NGS sequencing could be superior over to MLPA. [ABSTRACT FROM AUTHOR]

Muscular Dystrophies (MDs) are a group of inherited diseases and heterogeneous in nature. To date, 40 different genes have been reported for the occurrence and/or progression of MDs. This study was conducted to demonstrate the application of next-generation sequencing (NGS) in developing a time-saving and cost-effective diagnostic method to detect single nucleotide variants (SNVs) and copy number variants (CNVs) in a single test. A total of 123 cases clinically suspected of MD were enrolled in this study. Amplicon panel-based diagnosis was carried out for 102 (DMD/BMD) cases and the results were further screened using multiplex ligation-dependent probe amplification (MLPA). Whilst in the case of LGMD (N = 19) and UMD (N = 2), only NGS panel-based analysis was carried out. We identified the large deletions in 74.50% (76/102) of the cases screened with query DMD or BMD. Further, the large deletion in CAPN3 gene (N = 3) and known SNV mutations (N = 4) were identified in LGMD patients. Together, the total diagnosis rate for this amplicon panel was 70.73% (87/123) which demonstrated the utility of panel-based diagnosis for high throughput, affordable, and time-saving diagnostic strategy. Collectively, present study demonstrates that the panel based NGS sequencing could be superior over to MLPA.

Our objective was to investigate the potential of three microRNAs, miR-181a-5p, miR-30c-5p, and miR-206 as prognostic biomarkers for long-term follow up of Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD) patients. We analyzed the expression of three microRNAs in serum of 18 patients (DMD 13, BMD 5) and 13 controls using droplet digital PCR. Over 4 years a minimum of two and a maximum of three measurements were performed at different time points in the same patient. Correlations between microRNA serum levels, age, and functional outcome measures were analyzed. We show the individual evolution of the levels of the three microRNAs in 12 patients and also the effect of corticosteroid treatment on microRNAs expression. We measure the expression of three microRNAs in the muscle of six DMD patients and also the expression of target genes for miR-30c. We found that levels of miR-30c and miR-206 remained significantly elevated in DMD patients relative to controls over the entire study length. The introduction of the corticosteroid treatment did not significantly influence the levels of these microRNAs. We report a trend for microRNA levels to decrease with age. Moreover, miR-206 expression levels are capable to distinguish DMD from BMD patients according to ROC analysis. We found miR-30c expression decreased in the muscle of DMD patients and marked upregulation of the target genes for this microRNA. MiR-30c and miR-206 represent sensitive biomarkers for DMD, while miR-206 may have an additional value to distinguish the DMD and BMD phenotype. This may be particularly relevant to assess the effectiveness of treatments aimed at converting the DMD to the less-severe BMD like phenotype.

Abstract Background Duchenne (DMD) and Becker (BMD) muscular dystrophies are caused by mutations in the DMD gene coding for dystrophin, a protein being part of a large sarcolemmal protein scaffold that includes the neuronal nitric oxide synthase (nNOS). The nNOS was shown to play critical roles in a variety of muscle functions and alterations of its expression and location in dystrophic muscle fiber leads to an increase of the muscle fatigability. We previously revealed a decrease of nNOS expression in BMD patients all presenting a deletion of exons 45 to 55 in the DMD gene (BMDd45-55), impacting the nNOS binding site of dystrophin. Since several studies showed deregulation of microRNAs (miRNAs) in dystrophinopathies, we focused on miRNAs that could target nNOS in dystrophic context. Methods By a screening of 617 miRNAs in BMDd45-55 muscular biopsies using TLDA and an in silico study to determine which one could target nNOS, we selected four miRNAs. In order to select those that targeted a sequence of 3′UTR of NOS1, we performed luciferase gene reporter assay in HEK393T cells. Finally, expression of candidate miRNAs was modulated in control and DMD human myoblasts (DMDd45-52) to study their ability to target nNOS. Results TLDA assay and the in silico study allowed us to select four miRNAs overexpressed in muscle biopsies of BMDd45-55 compared to controls. Among them, only the overexpression of miR-31, miR-708, and miR-34c led to a decrease of luciferase activity in an NOS1-3′UTR-luciferase assay, confirming their interaction with the NOS1-3′UTR. The effect of these three miRNAs was investigated on control and DMDd45-52 myoblasts. First, we showed a decrease of nNOS expression when miR-708 or miR-34c were overexpressed in control myoblasts. We then confirmed that DMDd45-52 cells displayed an endogenous increased of miR-31, miR-708, and miR-34c and a decreased of nNOS expression, the same characteristics observed in BMDd45-55 biopsies. In DMDd45-52 cells, we demonstrated that the inhibition of miR-708 and miR-34c increased nNOS expression, confirming that both miRNAs can modulate nNOS expression in human myoblasts. Conclusion These results strongly suggest that miR-708 and miR-34c, overexpressed in dystrophic context, are new actors involved in the regulation of nNOS expression in dystrophic muscle.

Our objective was to investigate the potential of three microRNAs, miR-181a-5p, miR-30c-5p, and miR-206 as prognostic biomarkers for long-term follow up of Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD) patients. We analyzed the expression of three microRNAs in serum of 18 patients (DMD 13, BMD 5) and 13 controls using droplet digital PCR. Over 4 years a minimum of two and a maximum of three measurements were performed at different time points in the same patient. Correlations between microRNA serum levels, age, and functional outcome measures were analyzed. We show the individual evolution of the levels of the three microRNAs in 12 patients and also the effect of corticosteroid treatment on microRNAs expression. We measure the expression of three microRNAs in the muscle of six DMD patients and also the expression of target genes for miR-30c. We found that levels of miR-30c and miR-206 remained significantly elevated in DMD patients relative to controls over the entire study length. The introduction of the corticosteroid treatment did not significantly influence the levels of these microRNAs. We report a trend for microRNA levels to decrease with age. Moreover, miR-206 expression levels are capable to distinguish DMD from BMD patients according to ROC analysis. We found miR-30c expression decreased in the muscle of DMD patients and marked upregulation of the target genes for this microRNA. MiR-30c and miR-206 represent sensitive biomarkers for DMD, while miR-206 may have an additional value to distinguish the DMD and BMD phenotype. This may be particularly relevant to assess the effectiveness of treatments aimed at converting the DMD to the less-severe BMD like phenotype. [ABSTRACT FROM AUTHOR]

Introduction: Mutations in the 79 exons of the dystrophin gene result in muscle wasting and weakness of varying clinical severity, ranging from severe/typical Duchenne muscular dystrophy (DMD) to intermediate DMD and mild Becker muscular dystrophy (BMD), depending on the frameshift of the mutation. We previously reported that males with DMD have progressively declining appendicular lean mass (ALM) and ALM index (ALMI) with age and worsening functional motor ability compared with healthy controls. These indices have not been studied in patients with intermediate DMD and BMD phenotypes and across DMD genotypes. In this study, we compared age-related trajectories of ALM and ALMI of patients who had (1) BMD without functional mobility deficits with patients who had DMD at different stages of disease and healthy controls; (2) a DMD intermediate phenotype with patients who had a typical DMD phenotype; and (3) DMD categorized by genotype., Methods: We conducted a retrospective review of ALM and ALMI data from 499 patients (ages 5-23 years) with DMD (466 typical and 33 intermediate) and 46 patients (ages 5-21 years) with BMD (without functional mobility deficits and functional mobility score of 1). Patients were grouped according to age reflecting disease stage (ages 5 to <7, 7 to <10, 10 to <14, and 14 to <20 years) and genotype (mutations in exons 1-30, 31-44, 45-62, and 63-79)., Results: ALM and ALMI trajectories of patients with BMD paralleled those of healthy controls until adolescence, in contrast to patients with DMD. ALMI Z-scores of patients with BMD remained within ±2 SD without decline while those of patients with DMD fell below -2 SD around age 12 years. Patients with BMD had increasing ALM and ALMI with age, with peak accrual between ages 10 to <14 years. ALMI declined after age 14 years for those with intermediate DMD compared with 10 years for patients with typical DMD. Patients with mutations in exons 63-79 had a greater decline in ALMI as compared with those with other genotypes after age 10 years., Conclusions: Age-related changes in ALMI in patients with BMD and intermediate DMD differ from those with typical DMD, reflecting their clinical phenotypes. ALM and ALMI should be further studied in patients with BMD and DMD subtypes for their potential value as surrogate markers to characterize the severity of BMD and DMD and inform clinical care decisions and clinical trial designs., (© 2023 The Authors. Journal of Cachexia, Sarcopenia and Muscle published by Wiley Periodicals LLC.)

Objective Becker Muscular Dystrophy (BMD) is a neuromuscular disorder which is incurable. In this research protein interaction network of most associated proteins with BMD to provide better clarification of disorder underlying mechanism was investigated. Materials & Methods The related genes to BMD were retrieved via string database and conducted by Cytoscape and the related algorithms. The network centrality analysis was performed based on degree, betweenness, closeness, and stress parameters. Gene ontology and clustering were performed via ClueGO analysis. Results DMD as the super-hub as well as other central proteins including UTRN, TTN, DNM2, and RYR1 are important in BMD in terms of interactive features. The impairment of muscular contraction may be vital in BMD disease pathogenesis as it is the highlighted biological process term obtained by ClueGO analysis. Conclusion DMD targeting may be the main concern for dystrophy clinical approaches. However, the other suggested proteins should be evaluated. Targeting these key proteins are required for treatment goals following extensive validation studies. [ABSTRACT FROM AUTHOR]

In skeletal muscle, long noncoding RNAs (lncRNAs) are involved in dystrophin protein stabilization but also in the regulation of myocytes proliferation and differentiation. Hence, they could represent promising therapeutic targets and/or biomarkers for Duchenne and Becker muscular dystrophy (DMD/BMD). DMD and BMD are X-linked myopathies characterized by a progressive muscular dystrophy with or without dilatative cardiomyopathy. Two-thirds of DMD gene mutations are represented by deletions, and 63% of patients carrying DMD deletions are eligible for 45 to 55 multi-exons skipping (MES), becoming BMD patients (BMDΔ45-55). We analyzed the genomic lncRNA presence in 38 BMDΔ45-55 patients and characterized the lncRNA localized in introns 44 and 55 of the DMD gene. We highlighted that all four lncRNA are differentially expressed during myogenesis in immortalized and primary human myoblasts. In addition, the lncRNA44s2 was pointed out as a possible accelerator of differentiation. Interestingly, lncRNA44s expression was associated with a favorable clinical phenotype. These findings suggest that lncRNA44s2 could be involved in muscle differentiation process and become a potential disease progression biomarker. Based on these results, we support MES45-55 therapy and propose that the design of the CRISPR/Cas9 MES45-55 assay consider the lncRNA sequences bordering the exonic 45 to 55 deletion.

Li Zhang,1,* Zhe Liu,2,* Ke-You Hu,3 Qing-Bao Tian,3 Ling-Ge Wei,4 Zhe Zhao,5 Hong-Rui Shen,5 Jing Hu5 1Department of Cardiovascular Disorders, 2Department of Geriatrics, The Third Hospital of Hebei Medical University, 3The Public Health Department, Hebei Medical University, 4Department of Nuclear Medicine, 5Department of Neuromuscular Disorders, The Third Hospital of Hebei Medical University, Shijiazhuang, People’s Republic of China *Li Zhang and Zhe Liu are first coauthors of this paper Background: Early detection of muscular dystrophy (MD)-associated cardiomyopathy is important because early medical treatment may slow cardiac remodeling and attenuate symptoms of cardiac dysfunction; however, no sensitive and standard diagnostic method for MD at an earlier stage has been well-recognized. Thus, the aim of this study was to test the early diagnostic value of technetium 99m-methoxyisobutylisonitrile (99Tcm-MIBI) gated myocardial perfusion imaging (G-MPI) for MD.Methods and results: Ninety-one patients underwent 99Tcm-MIBI G-MPI examinations when they were diagnosed with Duchenne muscular dystrophy (DMD) (n=77) or Becker muscular dystrophy (BMD; n=14). 99Tcm-MIBI G-MPI examinations were repeated in 43 DMD patients who received steroid treatments for 2 years as a follow-up examination. Myocardial defects were observed in nearly every segment of the left ventricular wall in both DMD and BMD patients compared with controls, especially in the inferior walls and the apices by using 99Tcm-MIBI G-MPI. Cardiac wall movement impairment significantly correlated with age in the DMD and BMD groups (rs=0.534 [P

Background Diagnosis of Pompe disease is sometimes challenging because it exhibits clinical similarities to muscular dystrophy. Case We describe a case of Becker muscular dystrophy (BMD) with a remarkable reduction in activity of the acid α-glucosidase (GAA) enzyme, caused by a combination of pathogenic mutation and polymorphism variants resulting in pseudodeficiency in GAA . The three-year-old boy demonstrated asymptomatic creatine kinase elevation. Neither exon deletion nor duplication was detected on multiplex ligation-dependent probe amplification (MLPA) of DMD . GAA enzyme activity in both dried blood spots and lymphocytes was low, at 11.7% and 7.7% of normal, respectively. However, genetic analysis of GAA detected only heterozygosity for a nonsense mutation (c.118C > T, p.Arg40 ∗ ). Muscle pathology showed no glycogen deposits and no high acid phosphatase activity. Hematoxylin-eosin staining detected scattered regenerating fibers; the fibers were faint and patchy on immunochemistry staining of dystrophin. The amount of dystrophin protein was reduced to 11.8% of normal, on Western blotting analysis. Direct sequencing analysis of DMD revealed hemizygosity for a nonsense mutation (c.72G > A, p.Trp24 ∗ ). The boy was diagnosed with BMD, despite remarkable reduction in GAA activity; further, he demonstrated heterozygosity for [p.Gly576Ser; p.Glu689Lys] polymorphism variants that indicated pseudodeficiency on another allele in GAA . Conclusions Pseudodeficiency alleles are detected in approximately 4% of the Asian population; these demonstrate low activity of acid α-glucosidase (GAA), similar to levels found in Pompe disease. Clinicians should be careful in their interpretations of pseudodeficiency alleles that complicate diagnosis in cases of elevated creatine kinase. [ABSTRACT FROM AUTHOR]

The dystrophin gene ( DMD ) is the largest gene in the human genome, mapping on the Xp21 chromosome locus. It spans 2.2 Mb and accounts for approximately 0,1% of the entire human genome. Mutations in this gene cause Duchenne and Becker Muscular Dystrophy, X-linked Dilated Cardiomyopathy, and other milder muscle phenotypes. Beside the remarkable number of reports describing dystrophin gene expression and the pathogenic consequences of the gene mutations in dystrophinopathies, the full scenario of the DMD transcription dynamics remains however, poorly understood. Considering that the full transcription of the DMD gene requires about 16 h, we have investigated the activity of RNA Polymerase II along the entire DMD locus within the context of specific chromatin modifications using a variety of chromatin-based techniques. Our results unveil a surprisingly powerful processivity of the RNA polymerase II along the entire 2.2 Mb of the DMD locus with just one site of pausing around intron 52. We also discovered epigenetic marks highlighting the existence of four novel cis ‑DNA elements, two of which, located within intron 34 and exon 45, appear to govern the architecture of the DMD chromatin with implications on the expression levels of the muscle dystrophin mRNA. Overall, our findings provide a global view on how the entire DMD locus is dynamically transcribed by the RNA pol II and shed light on the mechanisms involved in dystrophin gene expression control, which can positively impact on the optimization of the novel ongoing therapeutic strategies for dystrophinopathies. [ABSTRACT FROM AUTHOR]

Background: Dystrophinopathy is one of the most common human monogenic diseases which results in Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD). Mutations in the dystrophin gene are responsible for both DMD and BMD. However, the clinical phenotypes and treatments are quite different in these two muscular dystrophies. Since early diagnosis and treatment results in better clinical outcome in DMD it is essential to establish accurate early diagnosis of DMD to allow efficient management. Previously, the reading-frame rule was used to predict DMD versus BMD. However, there are limitations using this traditional tool. Here, we report a novel molecular method to improve the accuracy of predicting clinical phenotypes in dystrophinopathy. We utilized several additional molecular genetic rules or patterns such as "ambush hypothesis", "hidden stop codons" and "exonic splicing enhancer (ESE)" to predict the expressed clinical phenotypes as DMD versus BMD. Results: A computer software "DMDtoolkit" was developed to visualize the structure and to predict the functional changes of mutated dystrophin protein. It also assists statistical prediction for clinical phenotypes. Using the DMDtoolkit we showed that the accuracy of predicting DMD versus BMD raised about 3% in all types of dystrophin mutations when compared with previous methods. We performed statistical analyses using correlation coefficients, regression coefficients, pedigree graphs, histograms, scatter plots with trend lines, and stem and leaf plots. Conclusions: We present a novel DMDtoolkit, to improve the accuracy of clinical diagnosis for DMD/BMD. This computer program allows automatic and comprehensive identification of clinical risk and allowing them the benefit of early medication treatments. DMDtoolkit is implemented in Perl and R under the GNU license. This resource is freely available at http://github.com/zhoujp111/DMDtoolkit, and http://www.dmd-registry.com. [ABSTRACT FROM AUTHOR]

ncRNAs are the most recently identified class of regulatory RNAs with vital functions in gene expression regulation and cell development. Among the variety of roles they play, their involvement in human diseases has opened new avenues of research towards the discovery and development of novel therapeutic approaches. Important data come from the field of hereditary muscle dystrophies, like Duchenne muscle dystrophy and Myotonic dystrophies, rare diseases affecting 1 in 7000–15,000 newborns and is characterized by severe to mild muscle weakness associated with cardiac involvement. Novel therapeutic approaches are now ongoing for these diseases, also based on splicing modulation. In this review we provide an overview about ncRNAs and their behavior in muscular dystrophy and explore their links with diagnosis, prognosis and treatments, highlighting the role of regulatory RNAs in these pathologies.

Highlights: [•] High frequency discharges (i.e., myotonic discharges and complex repetitive discharges) occur frequently in non-myotonic dystrophies as Pompe disease, sporadic inclusion body myositis, matrin 3 myopathy, and centronuclear myopathy. [•] High frequency discharges occur rarely in muscular dystrophies, e.g., facioscapulohumeral dystrophies and the limb girdle muscular dystrophies. [•] In non-myotonic myopathies, high frequency discharges are mainly composed of single elementary potentials, which discharge in a waning only or unchanging pattern, and are found frequently in the paravertebral muscles. [ABSTRACT FROM AUTHOR]

Objectives: This study sought to determine the clinical and biological significance of elevated cardiac troponin T (cTnT) in patients with neuromuscular diseases. Background: Practice guidelines regard cTnT and cardiac troponin I (cTnI) as equally sensitive and specific for the diagnosis of myocardial injury. Although cTnI is unique to myocardium, cTnT can be re-expressed in skeletal muscle in response to injury. The commercial cTnT assay is claimed to be cardiac specific. Methods: Fifty-two patients with 20 different types of acquired and inherited neuromuscular diseases underwent full clinical assessment, cardiac investigations, and measurements of serum cTnT, cTnI, creatine kinase (CK), creatine kinase myocardial band (CK-MB), and N-terminal pro-B–type natriuretic peptide (NT-proBNP). Results: Serial measurements (265 samples) in 25 initially hospitalized patients taken during a mean of 2.4 years showed persistent elevation of cTnT (median: 0.08 μg/l; interquartile range: 0.06 to 0.14 μg/l), CK (582 U/l; 303 to 3,662 U/l), and CK-MB (24 μg/l; 8 to 34 μg/l). In contrast, cTnI, measured using 2 sensitive assays, was persistently normal throughout the study in 22 patients. Electrocardiograms (ECGs) and echocardiograms were normal in 16 and 17 patients, respectively, and no serial changes were observed. Therapeutic interventions in patients with reversible myopathies normalized cTnT, CK, and CK-MB in unison. Single measurements in 27 ambulatory patients showed elevated CK (953 U/l; 562 to 1,320 U/l), CK-MB (18 μg/l; 11 to 28 μg/l), and cTnT (0.03 μg/l; 0.02 to 0.05 μg/l) in 21, 22, and 18 patients respectively. cTnI was abnormal in only 1 patient. NT-proBNP (41 pg/ml; 35 to 97 pg/ml) was normal in all but 2 patients. ECGs were normal in 15 patients. No patients with elevated cTnT, but with normal cTnI, had any cardiovascular events in either group during follow-up. Conclusions: Patients with a wide spectrum of neuromuscular diseases commonly have persistent elevation of cTnT and CK-MB in the absence of clinical and cTnI evidence of myocardial injury. Re-expressed cTnT in diseased skeletal muscle appears to be the source of the elevated cTnT detected in the circulation of these patients. [Copyright &y& Elsevier]

Abstract: The muscular dystrophies are a broad group of hereditary muscle diseases with variable severity. Population-based prevalence estimates have been reported but pooled estimates are not available. We performed a systematic review of worldwide population-based studies reporting muscular dystrophies prevalence and/or incidence using MEDLINE and EMBASE databases. The search strategy included key terms related to muscular dystrophies, incidence, prevalence and epidemiology. Two reviewers independently reviewed all abstracts, full text articles and abstracted data using standardized forms. Pooling of prevalence estimates was performed using random effect models. 1104 abstracts and 167 full text articles were reviewed. Thirty-one studies met all eligibility criteria and were included in the final analysis. The studies differed widely in their approaches to case ascertainment, resulting in significant methodological heterogeneity and varied data quality. The pooled prevalence of DMD and BMD was 4.78 (95% CI 1.94–11.81) and 1.53 (95% CI 0.26–8.94) per 100,000 males respectively. The incidence of DMD ranged from 10.71 to 27.78 per 100,000. This is the first meta-analysis of worldwide prevalence estimates for muscular dystrophies. There is a need for more epidemiological studies addressing global estimates on incidence and prevalence of muscular dystrophies, utilizing standardized diagnostic criteria as well as multiple sources of case ascertainment. [Copyright &y& Elsevier]

Abstract: Duchenne muscular dystrophy is caused by mutations that prevent synthesis of functional dystrophin. All patients develop dilated cardiomyopathy. Promising therapeutic approaches are underway that successfully restore dystrophin expression in skeletal muscle. However, their efficiency in the heart is limited. Improved quality and function of only skeletal muscle potentially accelerate the development of cardiomyopathy. Our study aimed to elucidate which dystrophin levels in the heart are required to prevent or delay cardiomyopathy in mice. Heart function and pathology assessed with magnetic resonance imaging and histopathological analysis were compared between 2, 6 and 10-month-old female mdx-Xist Δhs mice, expressing low dystrophin levels (3–15%) in a mosaic manner based on skewed X-inactivation, dystrophin-negative mdx mice, and wild type mice of corresponding genetic backgrounds and gender. With age mdx mice developed dilated cardiomyopathy and hypertrophy, whereas the onset of heart pathology was delayed and function improved in mdx-Xist Δhs mice. The ejection fraction, the most severely affected parameter for both ventricles, correlated to dystrophin expression and the percentage of fibrosis. Fibrosis was partly reduced from 9.8% in mdx to 5.4% in 10month old mdx-Xist Δhs mice. These data suggest that mosaic expression of 4–15% dystrophin in the heart is sufficient to delay the onset and ameliorate cardiomyopathy in mice. [Copyright &y& Elsevier]

Abstract: DMD gene which is composed of 79 exons is the largest known gene located on X chromosome (Xp21). Point mutations in the dystrophin gene are responsible for 30–35% of cases with DMD/BMD. Mutation analysis of all the exons of the DMD gene is costly in developing countries, therefore, a few of the exons are selected to be analyzed routinely in clinical laboratories. In this study, direct sequencing was used for detection of point mutations in 10 exons of dystrophin gene in patients affected with DMD without detectable large rearrangements. Freely available programs were used to predict the damaging effects of the mutations. Point mutations were successfully detected in three patients. Three novel mutations, two missense mutations located on nonconservative domains and a single nucleotide deletion, were detected. Missense mutations were predicted to change splicing efficiency. Detection of point mutations by DNA analysis followed by prediction of the pathogenecity by using bioinformatic tool might be an asset to provide proper diagnosis or genetic counseling to patients and their family. [Copyright &y& Elsevier]

Abstract: Dystrophin-deficiency causes cardiomyopathies and shortens the life expectancy of Duchenne and Becker muscular dystrophy patients. Restoring Dystrophin expression in the heart by gene transfer is a promising avenue to explore as a therapy. Truncated Dystrophin gene constructs have been engineered and shown to alleviate dystrophic skeletal muscle disease, but their potential in preventing the development of cardiomyopathy is not fully understood. In the present study, we found that either the mechanical or the signaling functions of Dystrophin were able to reduce the dilated heart phenotype of Dystrophin mutants in a Drosophila model. Our data suggest that Dystrophin retains some function in fly cardiomyocytes in the absence of a predicted mechanical link to the cytoskeleton. Interestingly, cardiac-specific manipulation of nitric oxide synthase expression also modulates cardiac function, which can in part be reversed by loss of Dystrophin function, further implying a signaling role of Dystrophin in the heart. These findings suggest that the signaling functions of Dystrophin protein are able to ameliorate the dilated cardiomyopathy, and thus might help to improve heart muscle function in micro-Dystrophin-based gene therapy approaches. [Copyright &y& Elsevier]

Purpose: Duchenne muscular dystrophy is a dystrophinopathy affecting males that is associated with multiple organ system complications. To our knowledge urological complications of Duchenne muscular dystrophy have been described only anecdotally to date. Materials and Methods: We reviewed the medical charts of 135 patients with Duchenne or Duchenne-Becker muscular dystrophy for demographics and disease progression, urological diagnoses, intervention and followup. Results: Of 135 patients 67 (50%) had at least 1 documented urological diagnosis and 38 (28%) had multiple manifestations. Lower urinary tract symptoms were the most common urological diagnosis (32% of patients). Survival analysis revealed a median age at onset of lower urinary tract symptoms of 23 years (95% CI 17.7-23.9). Intervention was required in 12 patients (9%), most commonly due to nephrolithiasis. Urological morbidity increased with Duchenne muscular dystrophy progression when stratified by clinical progression. Lower urinary tract symptoms were more common in nonambulatory patients (40.7% vs 19%, p = 0.007), those with a diagnosis of scoliosis (44% vs 19.7%, p = 0.003) and/or scoliosis spine surgery (60% vs 22%, p <0.001), and those on invasive respiratory support (53% vs 29%, p = 0.046). Likewise, nephrolithiasis was more common in nonambulatory patients (10% vs 0%, p = 0.017), those with scoliosis (12% vs 0%, p = 0.004) and/or scoliosis spine surgery (20% vs 1%, p <0.001), and those on invasive respiratory support (29% vs 3%, p <0.001). Only 28% of patients with a urological manifestation were referred to urology. Conclusions: As these patients transition into adolescence and adulthood, the increased prevalence of urological manifestations warrants increased awareness and referral to urologists. [Copyright &y& Elsevier]

ncRNAs are the most recently identified class of regulatory RNAs with vital functions in gene expression regulation and cell development. Among the variety of roles they play, their involvement in human diseases has opened new avenues of research towards the discovery and development of novel therapeutic approaches. Important data come from the field of hereditary muscle dystrophies, like Duchenne muscle dystrophy and Myotonic dystrophies, rare diseases affecting 1 in 7000-15,000 newborns and is characterized by severe to mild muscle weakness associated with cardiac involvement. Novel therapeutic approaches are now ongoing for these diseases, also based on splicing modulation. In this review we provide an overview about ncRNAs and their behavior in muscular dystrophy and explore their links with diagnosis, prognosis and treatments, highlighting the role of regulatory RNAs in these pathologies. [ABSTRACT FROM AUTHOR]

Abstract: In patients with muscular dystrophy, such as Duchenne muscular dystrophy (DMD), microcirculation abnormalities and hypoxic ischemic conditions in muscle tissues are suspected to be induced by non-symptomatic coagulation fibrinolysis abnormalities and vascular dysfunction. Vascular endothelial growth factor (VEGF) is a critical regulating factor in angiogenesis that is known to be induced by hypoxic and/or ischemic conditions. To examine whether VEGF is associated with muscular dystrophy, we measured serum levels of VEGF in 52 patients with DMD, 15 with Becker muscular dystrophy (BMD), 20 with Fukuyama congenital muscular dystrophy (FCMD), eight with myotonic dystrophy (DM), and four with spinal muscular atrophy (SMA), as well as in 15 healthy and eight disease controls. The serum level of VEGF in the DMD patients was 267.7±25.3pg/ml (10.5–800.0), while it was 358.8±96.3pg/ml (0.2–1320.0) in the BMD patients, 261.4±45.6pg/ml (0.1–758.0) in the FCMD patients, 165.0±63.4pg/ml (2.6–479.0) in the DM patients, 96.0±30.3pg/ml (41.0–168.0) in the SMA patients, 148.3±20.1pg/ml (46.5–298.0) in the healthy controls, and 154.1±54.0pg/ml (7.2–343.0) in the disease controls. The level of VEGF in BMD was significantly elevated, as compared with DM, SMA, and control groups. Further, the level of VEGF in the bedridden sub-group of DMD patients was significantly elevated as compared with chair-bound DMD, DM, SMA, and control groups. We concluded that VEGF may reflect hypoxic and/or ischemic conditions in muscle tissue, and have a relationship with the process of disease progression in DMD and BMD patients. [Copyright &y& Elsevier]

: ObjectivesWe investigated the integrity of dystrophin in left ventricle (LV) and right ventricle (RV) of patients with end-stage heart failure due to ischemic cardiomyopathy (IHD) or dilated cardiomyopathy (DCM), and compared the efficacy of pulsatile or continuous flow assist devices on dystrophin reverse remodeling.: BackgroundRecently we demonstrated that the amino (N)-terminus of dystrophin is preferentially disrupted in failing LV myocardium irrespective the underlying etiology, and that this defect is reversed by mechanical unloading using left ventricular assist device (LVAD) therapy.: MethodsMyocardial samples were obtained from seven normal controls, seven failing hearts (either DCM or IHD), and 14 failing-heart patients who underwent placement of either pulsatile (7 patients) or continuous flow (7 patients) LVADs for progressive refractory HF. The expression and integrity of dystrophin in these samples were determined by immunohistochemistry using antibodies against the N-terminal and carboxyl (C)-terminal domains.: ResultsImmunohistochemical staining identified disruption of the N-terminal dystrophin in both LVs and RVs of all seven failing-heart patients, whereas the C-terminus was normal. Furthermore, this disruption was reversed in 12 of the 14 patients after LVAD therapy using either pulsatile or continuous devices; the degree of the reverse remodeling was similar in both ventricles, although greater recovery was noted in patients treated with pulsatile flow devices.: ConclusionsIntegrity of the N-terminus of dystrophin is a useful indicator of both LV and RV function. In addition to improving LV hemodynamics, LVAD therapy results in amelioration of the myocardial structure of the right cardiac chamber. [Copyright &y& Elsevier]

Muscular dystrophies are a genetically heterogeneous group of degenerative muscle disorders. Nearly 30 genes are known to give rise to various forms of muscular dystrophy, which differ in age of onset, severity, and muscle groups affected. The number of genes identified increases each year, adding to our understanding as well as revealing the overall complexity of the pathogenesis of these diseases. [Copyright &y& Elsevier]

In skeletal muscle, long noncoding RNAs (lncRNAs) are involved in dystrophin protein stabilization but also in the regulation of myocytes proliferation and differentiation. Hence, they could represent promising therapeutic targets and/or biomarkers for Duchenne and Becker muscular dystrophy (DMD/BMD). DMD and BMD are X-linked myopathies characterized by a progressive muscular dystrophy with or without dilatative cardiomyopathy. Two-thirds of DMD gene mutations are represented by deletions, and 63% of patients carrying DMD deletions are eligible for 45 to 55 multi-exons skipping (MES), becoming BMD patients (BMDΔ45-55). We analyzed the genomic lncRNA presence in 38 BMDΔ45-55 patients and characterized the lncRNA localized in introns 44 and 55 of the DMD gene. We highlighted that all four lncRNA are differentially expressed during myogenesis in immortalized and primary human myoblasts. In addition, the lncRNA44s2 was pointed out as a possible accelerator of differentiation. Interestingly, lncRNA44s expression was associated with a favorable clinical phenotype. These findings suggest that lncRNA44s2 could be involved in muscle differentiation process and become a potential disease progression biomarker. Based on these results, we support MES45-55 therapy and propose that the design of the CRISPR/Cas9 MES45-55 assay consider the lncRNA sequences bordering the exonic 45 to 55 deletion. [ABSTRACT FROM AUTHOR]

Dystrophinopathies are caused by mutations in the DMD gene. Out-of-frame deletions represent most mutational events in severe Duchenne muscular dystrophy (DMD), while in-frame deletions typically lead to milder Becker muscular dystrophy (BMD). Antisense oligonucleotide-mediated exon skipping converts an out-of-frame transcript to an in-frame one, inducing a truncated but partially functional dystrophin protein. The reading frame rule, however, has many exceptions. We thus sought to simulate clinical outcomes of exon-skipping therapies for DMD exons from clinical data of exon skip-equivalent in-frame deletions, in which the expressed quasi-dystrophins are comparable to those resulting from exon-skipping therapies. We identified a total of 1298 unique patients with exon skip-equivalent mutations in patient registries and the existing literature. We classified them into skip-equivalent deletions of each exon and statistically compared the ratio of DMD/BMD and asymptomatic individuals across the DMD gene. Our analysis identified that five exons are associated with significantly milder phenotypes than all other exons when corresponding exon skip-equivalent in-frame deletion mutations occur. Most exon skip-equivalent in-frame deletions were associated with a significantly milder phenotype compared to corresponding exon skip-amenable out-of-frame mutations. This study indicates the importance of genotype-phenotype correlation studies in the rational design of exon-skipping therapies. [ABSTRACT FROM AUTHOR]

Valley sign has been described in patients with Duchenne muscular dystrophy (DMD). As there are genetic and clinical similarities between DMD and Becker muscular dystrophy (BMD), this clinical sign is evaluated in this study in BMD and DMD/BMD outliers. To evaluate the sign, 28 patients with Becker muscular dystrophy (BMD), 8 DMD/BMD outliers and 44 age-matched male controls with other neuromuscular diseases were studied. The sign was examined after asking patients to abduct their arms to about 90...with hands directed upwards; the muscle bulk over the back of the shoulders was observed. The sign was considered positive if the infraspinatus and deltoid muscles were enlarged and between these two muscles, the muscles forming the posterior axillary fold were wasted as if there were a valley between the two mounts. Twenty-five BMD patients and 7 DMD/BMD outliers had positive valley sign. However, it was less remarkable in comparison to DMD. It was absent in all the 44 controls. It was concluded that the presence of valley sign may help in differentiating BMD from other progressive neuromuscular disorders of that age group. [ABSTRACT FROM AUTHOR]

Background: An elevated level of creatine kinase (CK) is usually the primary screening marker for Duchenne muscular dystrophy (DMD)/Becker muscular dystrophy (BMD). This study investigated the clinical application of next-generation sequencing (NGS) in newborns with a possible diagnosis of DMD/BMD in the neonatal intensive care unit (NICU)., Methods: NGS data from the NICU between June 1, 2016, and June 30, 2020, were reanalyzed by an in-house pipeline. Other methods confirmed the genetic findings, and clinical follow-up was performed until August 1, 2020., Results: Of the 10,481 newborns, 19 (0.18%, 19/10,481) cases with pathogenic variations of the DMD gene were identified, including 13 (68.4%, 13/19) deletions, 4 (21.1%, 4/19) duplications, and 2 (10.5%, 2/19) nonsense mutations. Eight of the cases were diagnosed with DMD. Therapeutic strategies were modified for these patients. Six cases were diagnosed with BMD. Five patients except for 1 deceased patient were further followed-up, and clinical management was adjusted based on the clinical symptoms. The remaining 5 cases were indeterminate for DMD and BMD. Genetic counseling and further follow-up were performed or suggested., Conclusions: Our study showed that DMD/BMD could be diagnosed earlier in the neonatal stage before the typical clinical symptoms appear. Early diagnosis may provide an opportunity for guiding the care and treatment of patients. However, ethical issues need to be kept in mind in the process of genetic counseling., Competing Interests: Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at http://dx.doi.org/10.21037/atm-20-7102). The authors have no conflicts of interest to declare., (2021 Annals of Translational Medicine. All rights reserved.)

Background: Few studies have examined respiratory dysfunction in patients with Becker muscular dystrophy (BMD)., Objective: This study aimed to examine the characteristics of respiratory dysfunction in patients with BMD., Methods: The present retrospective study assessed respiratory parameters of adult BMD patients using medical records and compared these parameters with various patient characteristics to identify correlations. BMD patients aged 17 years and older who had been diagnosed genetically and/or pathologically were included in the analysis., Results: Of the source population of 133 patients, respiratory function was assessed in 85. Two of these patients had no symptoms, and eight had died. Mean % forced vital capacity (% FVC) was 94.2+/-21.7% (median, 96.1%; range, 5.1-134.1%). In 16 (19%) of the 85 patients, % FVC was <80%. Of these, seven were non-ambulant. Age, ambulation, and cardiac function did not significantly differ between patients with or without respiratory dysfunction, whereas age at onset was significantly lower in patients with respiratory dysfunction (7.7+/-4.7 years vs. 14.4+/-11.9 years; p = 0.001). One non-ambulant patient was a continuous NPPV user, and one patient had been recommended NPPV use but refused. Autopsy of one patient revealed that the diaphragm and intercostal muscles were less affected than proximal skeletal muscles., Conclusion: BMD patients are at risk of developing respiratory dysfunction due to dystrophic changes in respiratory muscles. Respiratory function should be carefully and periodically monitored in these patients.

Duchenne muscular dystrophy (DMD), a fatal X-linked recessive disorder, is caused mostly by frame-disrupting, out-of-frame deletions in the dystrophin (DMD) gene. Antisense oligonucleotide-mediated exon skipping is a promising therapy for DMD. Exon skipping aims to convert out-of-frame mRNA to in-frame mRNA and induce the production of internally-deleted dystrophin as seen in the less severe Becker muscular dystrophy. Currently, multiple exon skipping has gained special interest as a new therapeutic modality for this approach. Previous retrospective database studies represented a potential therapeutic application of multiple exon skipping. Since then, public DMD databases have become more useful with an increase in patient registration and advances in molecular diagnosis. Here, we provide an update on DMD genotype-phenotype associations using a global DMD database and further provide the rationale for multiple exon skipping development, particularly for exons 45–55 skipping and an emerging therapeutic concept, exons 3–9 skipping. Importantly, this review highlights the potential of multiple exon skipping for enabling the production of functionally-corrected dystrophin and for treating symptomatic patients not only with out-of-frame deletions but also those with in-frame deletions. We will also discuss prospects and challenges in multiple exon skipping therapy, referring to recent progress in antisense chemistry and design, as well as disease models. [ABSTRACT FROM AUTHOR]

Background: Obtaining an adequate number of patients to conduct a natural history study for rare diseases such as Becker muscular dystrophy (BMD) is difficult., Objectives: The present study used data from Remudy, a national registry for neuromuscular diseases in Japan, to conduct a phenotypic analysis of BMD., Methods: We analyzed Remudy data of participants with dystrophinopathy. All participants who were aged 17 and older and were ambulant at age 13 were included in this study. Participants were divided into two groups: those with BMD who were ambulant at age 17, and those with intermediate muscular dystrophy (IMD) who lost ambulation by age 17. Frequent mutations were analyzed by age at ambulation, cardiopulmonary function, and genotype. For clinical comparisons, participants who were administered steroids were excluded., Results: From July 2009 through September 2015, 192 participants had registered with Remudy. Mean participant age was 34.80±13.3 (range, 17-78) years, and 52.1% of participants were ambulant. Of the entire study population, 50.5% had cardiomyopathy and 35.9% had respiratory failure. Three participants required invasive ventilation and 30 required non-invasive ventilation. Nineteen of the 30 non-invasive ventilator users were part-time users. In total, 138 (71.9%) had BMD and 54 (28.1%) had IMD. The most frequent mutation was ex45&#95;ex47del (36 participants). Among participants with frequent in-frame mutations, those with the ex45-49del mutation lost their ambulation earlier than those with the ex45&#95;ex47del mutation. A total of 67 different exon deletions and duplications were identified in the study population., Conclusion: We clarified the clinical phenotypes of Japanese patients with BMD/IMD using data from Remudy. Our results suggest that not only IMD but also BMD are associated with risk of respiratory dysfunction.

Exon-skipping therapy is an emerging approach that uses synthetic DNA-like molecules called antisense oligonucleotides (ASOs) to splice out frame-disrupting parts of mRNA, restore the reading frame, and produce truncated yet functional proteins. Phosphorodiamidate morpholino oligomer (PMO) is one of the safest among therapeutic ASOs for patients and has recently been approved under the accelerated approval program by the US Food and Drug Administration (FDA) as the first ASO-based drug for Duchenne muscular dystrophy (DMD). Multi-exon skipping utilizing ASOs can theoretically treat 80-90% of patients with DMD. Here, we describe the systemic delivery of a cocktail of ASOs to skip exon 51 and exons 45-55 in the mdx52 mouse, an exon 52 deletion model of DMD produced by gene targeting, and the evaluation of their efficacies in vivo.