Diagnosis and management of Duchenne muscular dystrophy, part 2: implementation of multidisciplinary care

Respiratory characterization of a humanized Duchenne muscular dystrophy mouse model

Duchenne muscular dystrophy (DMD) is the most common X-linked disease. DMD is caused by a lack of dystrophin, a critical structural protein in striated muscle. Dystrophin deficiency leads to inflammation, fibrosis, and muscle atrophy. Boys with DMD have progressive muscle weakness within the diaphragm that results in respiratory failure in the 2nd or 3rd decade of life. The most common DMD mouse model - the mdx mouse - is not sufficient for evaluating genetic medicines that specifically target the human DMD (hDMD) gene sequence. Therefore, a novel transgenic mouse carrying the hDMD gene with an exon 52 deletion was created (hDMDΔ52;mdx). We characterized the respiratory function and pathology in this model using whole body plethysmography, histology, and immunohistochemistry. At 6-months-old, hDMDΔ52;mdx mice have reduced maximal respiration, neuromuscular junction pathology, and fibrosis throughout the diaphragm, which worsens at 12-months-old. In conclusion, the hDMDΔ52;mdx exhibits moderate respiratory pathology, and serves as a relevant animal model to study the impact of novel genetic therapies, including gene editing, on respiratory function.

Motor dysfunction of the gut in Duchenne muscular dystrophy: A review

BACKGROUND

Duchenne's muscular dystrophy (DMD) is a severe type of hereditary, neuromuscular disorder caused by a mutation in the dystrophin gene resulting in the absence or production of truncated dystrophin protein. Conventionally, clinical descriptions of the disorder focus principally on striated muscle defects; however, DMD manifestations involving gastrointestinal (GI) smooth muscle have been reported, even if not rigorously studied.

PURPOSE

The objective of the present review is to offer a comprehensive perspective on the existing knowledge concerning GI manifestations in DMD, focusing the attention on evidence in DMD patients and mdx mice. This includes an assessment of symptomatology, etiological pathways, and potential corrective approaches. This paper could provide helpful information about DMD gastrointestinal implications that could serve as a valuable orientation for prospective research endeavors in this field. This manuscript emphasizes the effectiveness of mdx mice, a DMD animal model, in unraveling mechanistic insights and exploring the pathological alterations in the GI tract. The gastrointestinal consequences evident in patients with DMD and the mdx mice models are a significant area of focus for researchers. The exploration of this area in depth could facilitate the development of more efficient therapeutic approaches and improve the well-being of individuals impacted by the condition.

Maintaining Physical Health in Individuals with Duchenne Muscular Dystrophy Through Telerehabilitation

AIMS

To investigate the effects of a telerehabilitation program on walking performance, lower and upper extremity function, fall frequency, respiratory function, and satisfaction in individuals with Duchenne muscular dystrophy (DMD).

METHODS

Thirty children (mean age 8.8 ± 4.2 years) were ambulant (Group 1), and 12 youth (18.5 ± 4.7 years) were non-ambulant (Group 2). The telerehabilitation program was applied by physiotherapists for 24 sessions (3 days/week). The 10-meter walking test, stand up from the supine position test, the modified upper extremity performance test, repetition of Lower and upper extremity movements, and the single breath count (SBC) test were administered. Fall frequency and satisfaction level were also recorded.

RESULTS

Significant improvement was found after telerehabilitation in upper extremity performance, repetition of lower and upper extremity movements, fall frequency, and SBC scores in Group 1. Changes in the 10-minute Walk and Stand Up from the Supine Position tests were not significant. There was a significant improvement in SBC scores in Group 2. Satisfaction with the service was 88%.

CONCLUSIONS

The 8-week telerehabilitation program was effective in improving aspects of upper and lower extremity function, fall frequency, pulmonary function, and satisfaction levels in individuals with DMD.

Different bone health progression patterns and early-stage risk marker in glucocorticoid-treated ambulatory Duchenne muscular dystrophy

Fractures often cause irreversible harm in Duchenne muscular dystrophy (DMD). This study investigated the trajectory of bone mineral density (BMD) using group-based trajectory modeling and identified that BMD acts as an early-stage indicator of clinically significant bone fragility. The greater the early-stage BMD, the better the 4-year bone health outcome.

PURPOSE

Most Duchenne muscular dystrophy (DMD) children suffer bone loss after long-term glucocorticoid (GC) exposure, which induces scoliosis and fragility fractures. To assess the BMD progression pattern and individual medical risk markers for these phenotypes in young ambulatory boys with DMD, and provide evidence-based suggestions for clinical management of bone health.

METHODS

A retrospective longitudinal cohort study of 153 boys with DMD in West China Second University Hospital (2016-2023) was performed. Group-based trajectory modeling was used to study the BMD progression pattern, and potential predictors were further analyzed by logistic regression and survival analysis.

RESULTS

One hundred and fifty-three participants were included, 71 of which had more than 3 BMD records. Three BMD trajectories were identified. Baseline BMD and age-started GC and were independent predictors of trajectory attribution. The median survival time of the first observation of low BMD in GC-treated DMD boys was 5.32 (95% CI 4.05-6.59) years, and a significant difference was tested (P < 0.001) among the three trajectory groups.

CONCLUSION

BMD may serve as a novel early indicating marker for monitoring bone fragility for DMD. We proposed a bone health risk stratification through BMD progression trajectory that allows us to adapt the osteoporosis warning sign in DMD from a fixed threshold approach to a more individualized strategy, where baseline BMD and age of glucocorticoid initiation can provide an earlier prediction of bone loss. Better management of primary BMD may be able to delay or avoid the onset of adverse bone health outcomes in the fifth year in children with DMD.

Chronic Pain in Patients with Spinal Muscular Atrophy in Switzerland: A Query to the Spinal Muscular Atrophy Registry

Background and Objectives: Chronic pain is a common symptom in various types of neuromuscular disorders. However, for patients with spinal muscular atrophy (SMA), the literature regarding chronic pain is scarce. Thus, this study assessed the prevalence of chronic pain in children, adolescents, and adults with SMA and investigated the influence of clinical characteristics on chronic pain. Materials and Methods: This study used data from 141 patients, which were collected by the Swiss Registry for Neuromuscular Disorders. Extracted data included information on pain (present yes/no, pain location, and pain medication) and clinical characteristics, such as SMA type, motor function, wheelchair use, scoliosis, and contractures. Results: The analyses revealed that the highest prevalence of chronic pain was observed in adolescents with 62%, followed by adults with 48%, children (6-12 years) with 39%, and children < 6 years with 10%. The legs, back, and hips were most frequently reported as pain locations. Sex (females), age (adolescents), and the presence of contractures and scoliosis (with surgery) were factors that were associated with chronic pain. Conclusions: These findings contribute to a better understanding of pain in SMA, shedding light on its prevalence and characteristics in different age groups, which underscores the importance of assessing and managing pain in patients with SMA.

Production of Duchenne muscular dystrophy cellular model using CRISPR-Cas9 exon deletion strategy

Duchenne Muscular Dystrophy (DMD) is a progressive muscle wasting disorder caused by loss-of-function mutations in the dystrophin gene. Although the search for a definitive cure has failed to date, extensive efforts have been made to introduce effective therapeutic strategies. Gene editing technology is a great revolution in biology, having an immediate application in the generation of research models. DMD muscle cell lines are reliable sources to evaluate and optimize therapeutic strategies, in-depth study of DMD pathology, and screening the effective drugs. However, only a few immortalized muscle cell lines with DMD mutations are available. In addition, obtaining muscle cells from patients also requires an invasive muscle biopsy. Mostly DMD variants are rare, making it challenging to identify a patient with a particular mutation for a muscle biopsy. To overcome these challenges and generate myoblast cultures, we optimized a CRISPR/Cas9 gene editing approach to model the most common DMD mutations that include approximately 28.2% of patients. GAP-PCR and sequencing results show the ability of the CRISPR-Cas9 system to efficient deletion of mentioned exons. We showed producing truncated transcript due to the targeted deletion by RT-PCR and sequencing. Finally, mutation-induced disruption of dystrophin protein expression was confirmed by western blotting. All together, we successfully created four immortalized DMD muscle cell lines and showed the efficacy of the CRISPR-Cas9 system for the generation of immortalized DMD cell models with the targeted deletions.

Duchenne muscular dystrophy caused by a deletion (c.5021del) in exon 35 of the DMD gene: A case report and review of the literature

Duchenne muscular dystrophy (DMD MIM#310200) is a degenerative muscle disease caused by mutations in the dystrophin gene located on Xp21.2. The clinical features encompass muscle weakness and markedly elevated serum creatine kinase levels. An 8-year-old Chinese boy was diagnosed with Duchenne muscular dystrophy (DMD). Whole exome gene sequencing was conducted and the Sanger method was used to validate sequencing. A deletion (c.5021del) in exon 35 of the dystrophin gene was identified, which was predicted to generate a frameshift mutation and create an early termination codon (p.Leu1674CysfsTer47). It has a pathogenic effect against dystrophin in the muscle cell membrane of the patient. As such, prednisone treatment at a dose of 0.75 mg/kg.d was administered. After one month, a notable reduction in fall frequency was observed. Our new finding will expand the pathogenic mutation spectrum causing DMD.

A review on mechanistic insights into structure and function of dystrophin protein in pathophysiology and therapeutic targeting of Duchenne muscular dystrophy

Duchenne Muscular Dystrophy (DMD) is an X-linked recessive genetic disorder characterized by progressive and severe muscle weakening and degeneration. Among the various forms of muscular dystrophy, it stands out as one of the most common and impactful, predominantly affecting boys. The condition arises due to mutations in the dystrophin gene, a key player in maintaining the structure and function of muscle fibers. The manuscript explores the structural features of dystrophin protein and their pivotal roles in DMD. We present an in-depth analysis of promising therapeutic approaches targeting dystrophin and their implications for the therapeutic management of DMD. Several therapies aiming to restore dystrophin protein or address secondary pathology have obtained regulatory approval, and many others are ongoing clinical development. Notably, recent advancements in genetic approaches have demonstrated the potential to restore partially functional dystrophin forms. The review also provides a comprehensive overview of the status of clinical trials for major therapeutic genetic approaches for DMD. In addition, we have summarized the ongoing therapeutic approaches and advanced mechanisms of action for dystrophin restoration and the challenges associated with DMD therapeutics.

Trilobatin contributes to the improvement of myopathy in a mouse model of Duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD) occurs due to genetic mutations that lead to a deficiency in dystrophin production and consequent progressive degeneration of skeletal muscle fibres, through oxidative stress and an exacerbated inflammatory process. The flavonoid trilobatin (TLB) demonstrates antioxidant and anti-inflammatory potential. Its high safety profile and effective action make it a potent therapy for the process of dystrophic muscle myonecrosis. Thus, we sought to investigate the action of TLB on damage in a DMD model, the mdx mouse. Eight-week-old male animals were treated with 160 mg/kg/day of trilobatin for 8 weeks. Control animals were treated with saline. Following treatment, muscle strength, serum creatine kinase (CK) levels, histopathology (necrotic myofibres, regenerated fibres/central nuclei, Feret's diameter and inflammatory area) and the levels of catalase and NF-κB (western blotting) of the quadriceps (QUA), diaphragm (DIA) and tibialis anterior (TA) muscles were measured. TLB was able to significantly increase muscle strength and reduce serum CK levels in dystrophic animals. The QUA of mdx mice showed a reduction in catalase and the number of fibres with a centralized nucleus after treatment with TLB. In the DIA of dystrophic animals, TLB reduced the necrotic myofibres, inflammatory area and NF-κB and increased the number of regenerated fibres and the total fibre diameter. In TA, TLB increased the number of regenerated fibres and reduced catalase levels in these animals. It is concluded that in the mdx experimental model, treatment with TLB was beneficial in the treatment of DMD.

[Screening for Duchenne muscular dystrophy in newborns in the Ningxia region]

OBJECTIVES

To evaluate the incidence rate of Duchenne muscular dystrophy (DMD) in the male newborns in the Ningxia region and establish a critical threshold for screening DMD in newborns to distinguish between the normal population and affected individuals.

METHODS

A total of 10 000 male newborns were screened using immunofluorescence analysis of creatine kinase isoenzyme concentrations in heel spot dried blood specimens. Newborns with the concentrations higher than the critical threshold were recalled for serum creatine kinase measurements. Genetic testing was performed to confirm diagnosis in cases showing abnormalities.

RESULTS

Among the screened 10 000 male newborns, two were confirmed to have DMD through genetic testing, resulting in a preliminary estimated incidence rate of 1/5 000 for male newborns in the Ningxia region. The critical threshold for creatine kinase isoenzyme concentration in newborns in this region was determined to be 468.57 ng/mL.

CONCLUSIONS

Screening for DMD in newborns is feasible in the Ningxia region. Early screening, diagnosis, and treatment of DMD can improve the quality of life for affected individuals and help families make informed decisions regarding further pregnancies.

Can postural changes in spirometry in children with Duchenne muscular dystrophy predict sleep hypoventilation?

AIM

To explore the relationship between postural changes in lung function and polysomnography (PSG) in children with Duchenne muscular dystrophy (DMD).

METHODS

In this prospective cross-sectional study, children with DMD performed spirometry in sitting and supine positions. A control group of age and gender matched healthy children also underwent postural lung function testing. PSG was performed within six months of spirometry.

RESULTS

Seventeen children with DMD, aged 12.3 ± 3 years performed sitting spirometry. 14 (84%) performed acceptable spirometry in the supine position. Mean FEV1sit and FVCsit were 77% (SD ± 22) and 74% (SD ± 20.4) respectively, with mean% ΔFVC(sit-sup) 9% (SD ± 11) (range 2% to 20%), and was significantly greater than healthy controls 4% (n = 30, SD ± 3, P < 0.001). PSG data on the 14 DMD children with acceptable supine spirometry showed total AHI 6.9 ± 5.9/hour (0.3 to 29), obstructive AHI 5.2 ± 4.0/hour (0.2 to 10), and REM AHI 14.1 ± -5.3/hour (0.1 to 34.7). ΔFVC(sit-sup) had poor correlation with hypoventilation on polysomnography.

CONCLUSION

Children with DMD and mild restrictive lung disease showed greater postural changes in spirometry than healthy controls but lower supine spirometry was not predictive of sleep hypoventilation.

Association Between Myocardial Oxygenation and Fibrosis in Duchenne Muscular Dystrophy: Analysis by Rest Oxygenation-Sensitive Magnetic Resonance Imaging

BACKGROUND

Myocardial hypoxia has been demonstrated in many cardiomyopathies and is related to development of myocardial fibrosis. However, myocardial hypoxia and its association with myocardial fibrosis are understudied in Duchenne muscular dystrophy (DMD)-associated cardiomyopathy.

PURPOSE

To evaluate myocardial hypoxia by oxygenation-sensitive (OS) cardiac magnetic resonance imaging, and further explore its association with fibrosis.

STUDY TYPE

Prospective.

SUBJECTS

Ninety-one DMD boys (8.78 ± 2.32) and 30 healthy boys (9.07 ± 2.30).

FIELD STRENGTH/SEQUENCE

3 T, Balanced steady-state free procession, Modified Look-Locker inversion recovery sequence and Single-shot phase-sensitive inversion recovery sequence.

ASSESSMENT

Cardiac MRI data, including left ventricular functional, segmental native T1, and oxygenation signal-intensity (SI) according to AHA 17-segment model, were acquired. Patients were divided into LGE+ and LGE- groups. In patients with LGE, all segments were further classified as positive or negative segments by segmentally presence/absence of LGE.

STATISTICAL TESTS

Variables were compared using Student's t, Wilcoxon, Kruskal-Wallis test and one-way analysis of variance. Bivariate Pearson or Spearman correlation were calculated to determine association between oxygenation SI and native T1. Variables with P < 0.10 in the univariable analysis were included in multivariable model. Receiver operating characteristic analysis was used to assess the performance of OS in diagnosing myocardial hypoxia.

RESULTS

The myocardial oxygenation SI of DMD was significantly decreased in all segments compared with normal controls, and more obvious in the LGE+ segments (0.46 ± 0.03 vs. 0.52 ± 0.03). For patients with and without LGE, myocardial oxygenation SI were significantly negatively correlated with native T1 in all segments (r = -0.23 to -0.42). The inferolateral oxygenation SI was a significant independent associator of LGE presence (adjusted OR = 0.900).

DATA CONCLUSION

Myocardial hypoxia evaluated by the OS-Cardiac-MRI indeed occurs in DMD and associate with myocardial fibrosis, which might be used as a biomarker in assessing myocardial damage in DMD.

EVIDENCE LEVEL

1 TECHNICAL EFFICACY: Stage 1.

Hematopoietic Prostaglandin D Synthase Is Increased in Mast Cells and Pericytes in Autopsy Myocardial Specimens from Patients with Duchenne Muscular Dystrophy

The leading cause of death for patients with Duchenne muscular dystrophy (DMD), a progressive muscle disease, is heart failure. Prostaglandin (PG) D2, a physiologically active fatty acid, is synthesized from the precursor PGH2 by hematopoietic prostaglandin D synthase (HPGDS). Using a DMD animal model (mdx mice), we previously found that HPGDS expression is increased not only in injured muscle but also in the heart. Moreover, HPGDS inhibitors can slow the progression of muscle injury and cardiomyopathy. However, the location of HPGDS in the heart is still unknown. Thus, this study investigated HPGDS expression in autopsy myocardial samples from DMD patients. We confirmed the presence of fibrosis, a characteristic phenotype of DMD, in the autopsy myocardial sections. Additionally, HPGDS was expressed in mast cells, pericytes, and myeloid cells of the myocardial specimens but not in the myocardium. Compared with the non-DMD group, the DMD group showed increased HPGDS expression in mast cells and pericytes. Our findings confirm the possibility of using HPGDS inhibitor therapy to suppress PGD2 production to treat skeletal muscle disorders and cardiomyopathy. It thus provides significant insights for developing therapeutic drugs for DMD.

Dual task impact on functional mobility and interaction of functional level and balance in patients with Duchenne muscular dystrophy

BACKGROUND

Dystrophin, a protein crucial for various brain regions governing higher-order functions like learning and memory is notably absent in individuals with Duchenne muscular dystrophy (DMD). This absence of dystrophin in the brain is believed to underlie cognitive challenges in DMD. Cognitive and motor challenges observed in DMD could potentially hinder the execution of dual tasks.

RESEARCH QUESTION

Is there a significant correlation between dual-task performance, functional mobility, and balance in children with DMD?

METHOD

The study included 28 participants (14 DMD, 14 typical development). Timed Up and Go (TUG) test results were recorded for single and dual-task conditions (motor-motor, cognitive-motor). Functional level was assessed using Motor Function Measurement-32 (MFM-32), Brooke Upper Extremity Scale, and Vignos Scale. Balance was evaluated using Balance Master System and Pediatric Functional Reach Test (PFRT).

RESULTS

Significant differences in TUG test scores across conditions were observed in both DMD and typical development groups (p < 0.05). Children with DMD exhibited longer completion times compared to typical development children (p < 0.05). Among children with DMD, there was a significant correlation between TUG scores in different task conditions and balance assessment (p < 0.05, r = 0.571 to -0.819). Lower MFM-32 scores in DMD children were correlated with worse TUG performance across conditions (p < 0.05, r = 0.586 to -0.868).

SIGNIFIANCE

This study sheds light on the multifaceted nature of dual-tasking challenges in individuals with DMD, thereby contributing to a deeper understanding of the implications for rehabilitation strategies.

Duchenne Muscular Dystrophy Fatigue Trajectories

INTRODUCTION

 Children with Duchenne muscular dystrophy (DMD) are at risk of experiencing fatigue that negatively impacts their health-related quality of life (HRQoL). This study aimed to assess the association between fatigue and HRQoL, by examining fatigue trajectories over 48 weeks, and assessing factors associated with these fatigue trajectories.

METHODS

 The study sample consisted of 173 DMD subjects enrolled in a 48-week-long phase 2 clinical trial (NCT00592553) for a novel therapeutic who were between the ages of 5 and 16 years.

RESULTS

 The results of regression modeling show baseline fatigue and baseline HRQoL (R 2 = 0. 54 for child self-report and 0.51 for parent proxy report) and change in fatigue and HRQoL over 48 weeks (R 2 = 0.47 for child self-report and 0.36 for parent proxy report) were significantly associated with one another. Three unique fatigue trajectories using Latent Class Growth Models were identified for child and parent proxy reported fatigue. The risk of being in the high fatigue group as compared to the low fatigue group increased by 24% with each year increase in age and also with decreasing walking distance, as reported by children and parent proxy, respectively.

CONCLUSION

 This study identified fatigue trajectories and risk factors associated with greater fatigue, helping clinicians and researchers identify the profile of fatigue in DMD children.

Characteristics of Patients Receiving Novel Muscular Dystrophy Drugs in Trials vs Routine Care

Importance

The US Food and Drug Administration approved eteplirsen for Duchenne muscular dystrophy (DMD) in 2016 based on a controversial pivotal study that demonstrated a limited effect on the surrogate measure of dystrophin production. Other DMD treatments in the same class followed.

Objective

To assess how patients receiving novel DMD treatments in postapproval clinical settings compare with patients in the clinical trials.

Design, Setting, and Participants

This cross-sectional study collected data on patients who initiated 1 of 4 novel DMD treatments (eteplirsen, golodirsen, viltolarsen, and casimersen) using national claims databases of commercially insured (Merative MarketScan and Optum's Clinformatics Data Mart Database [CDM]) and Medicaid patients between September 19, 2016, and March 31, 2022. Patients were followed for 1 year after the date of first use of any novel DMD treatment. In addition, patients in pivotal DMD drug trials were identified for comparison.

Exposures

Age, sex, race and ethnicity, region, and DMD stage of patients receiving novel DMD treatment.

Main Outcome and Measures

The main outcome was health care costs and drug discontinuation as measured using descriptive statistics.

Results

A total of 223 routine care patients initiating novel DMD drugs (58 in MarketScan, 35 in CDM, and 130 in Medicaid) were identified. Among the 106 patients in the pivotal trials, the mean (SD) age was 8.5 (2.0) years (range, 4.0-13.0 years), which was younger than the mean age of patients in routine care (MarketScan: 13.7 [7.0] years [range, 1.8-33.3 years; P < .001]; CDM: 11.9 [5.7] years [range, 0.6-23.6 years; P < .001]; Medicaid: 13.4 [6.5] years [range, 1.8-46.1 years; P < .001]). The proportion of female patients identified in postapproval clinical settings was 2.9% (n = 1) in CDM (vs 34 male patients [97.1%]) and 1.5% (n = 2) in Medicaid (vs 128 male patients [98.5%]), which was not different from the pivotal trials. While nearly all patients in the pivotal trials had DMD disease stage 1 or 2 when initiating the DMD treatments (103 [97.2%]), in the postapproval clinical setting, slightly more than one-third of patients were in disease stage 3 or 4 (MarketScan, 17 [36.2%; P < .001]; CDM, 13 [41.9%; P < .001]; Medicaid, 54 [47.0%; P < .001]). The payer's cost for novel DMD treatments varied across the databases, with a mean (SD) of $634 764 ($607 101) in MarketScan, $482 749 ($582 350) in CDM, and $384 023 ($1 165 730) in Medicaid. Approximately one-third of routine care patients discontinued the treatments after approximately 7 months (mean [SD], 6.1 [4.4], 6.9 [3.9], and 7.2 [4.3] months in MarketScan, CDM, and Medicaid, respectively).

Conclusions and Relevance

These findings raise questions about the translation of DMD drug trial findings to routine care settings, with patients in routine care discontinuing the treatment within 1 year and payers incurring substantial expenses for these medications. More data are needed on whether these high costs are accompanied by corresponding clinical benefits.

Early assessment of cardiomyopathy in Duchenne patients by means of longitudinal strain echocardiography

INTRODUCTION

The diagnosis of Duchenne-linked cardiomyopathy may be challenging. Conventional echocardiographic measurements typically show deterioration beyond the second decade. Global longitudinal strain has been proposed as an earlier marker than left ventricular ejection fraction.

MATERIAL AND METHODS

A prospective, observational, cross-sectional, case-control study was carried out. Both Duchenne patients and control subjects underwent transthoracic echocardiogram in order to assess left ventricle function. Bayesian linear regression was the main tool for inference. Age effects were parameterised by means of a spline function because of its simplicity to characterise continuous variables and smooth contributions. The posterior distribution of the marginal age effects was used to assess the earliest age of deterioration of each marker.

RESULTS

Sixteen Duchenne patients and twenty-two healthy male subjects were enrolled. On overage, cardiac function measures were found for ejection fraction and longitudinal strain among different groups. Age effects on global longitudinal strain are more reliably found at ages of 6 and above, while ejection fraction starts to deteriorate at an older age. Progressive left ventricular dysfunction in Duchenne patients is one of the key issues and starts at an early age with subtle symptoms.

CONCLUSION

This cross-sectional study provides supporting evidence that global longitudinal strain is an earlier marker of disease progression than ejection fraction in Duchenne patients.

Prophylactic use of cardiac medications for delay of left ventricular dysfunction in Duchenne muscular dystrophy

BACKGROUND

Epidemiological support for prophylactic treatment of left ventricular dysfunction (LVD) in Duchenne muscular dystrophy is limited. We used retrospective, population-based surveillance data from the Muscular Dystrophy Surveillance, Tracking and Research Network to evaluate whether prophylaxis delays LVD onset.

METHODS

We analyzed 455 males born during 1982-2009. Age at first abnormal echocardiogram (ejection fraction <55% or shortening fraction <28%) determined LVD onset. Prophylaxis was defined as cardiac medication use at least 1 year prior to LVD. Corticosteroid use was also coded. Kaplan-Meier curve estimation and Cox Proportional Hazard modeling with time-varying covariates describe associations.

RESULTS

LVD was identified among 40.7%; average onset age was 14.2 years. Prophylaxis was identified for 20.2% and corticosteroids for 57.4%. Prophylaxis showed delayed LVD onset (p < .001) and lower hazard of dysfunction (adjusted hazard ratio [aHR] = 0.39, 95%CL = 0.22, 0.65) compared to untreated. Compared to no treatment, continuous corticosteroids only (aHR = 1.01, 95%CL = 0.66, 1.53) and prophylaxis only (aHR = 0.67, 95%CL = 0.25, 1.50) were not cardioprotective, but prophylaxis plus continuous corticosteroids were associated with lower hazard of dysfunction (aHR = 0.37, 95%CL = 0.15, 0.80).

CONCLUSIONS

Proactive cardiac treatment and monitoring are critical aspects of managing Duchenne muscular dystrophy. Consistent with clinical care guidelines, this study supports clinical benefit from cardiac medications initiated prior to documented LVD and suggests further benefit when combined with corticosteroids.

Draft Guidance for Industry Duchenne Muscular Dystrophy, Becker Muscular Dystrophy, and Related Dystrophinopathies - Developing Potential Treatments for the Entire Spectrum of Disease

Background

Duchenne muscular dystrophy (DMD) and related dystrophinopathies are neuromuscular conditions with great unmet medical needs that require the development of effective medical treatments.

Objective

To aid sponsors in clinical development of drugs and therapeutic biological products for treating DMD across the disease spectrum by integrating advancements, patient registries, natural history studies, and more into a comprehensive guidance.

Methods

This guidance emerged from collaboration between the FDA, the Duchenne community, and industry stakeholders. It entailed a structured approach, involving multiple committees and boards. From its inception in 2014, the guidance underwent revisions incorporating insights from gene therapy studies, cardiac function research, and innovative clinical trial designs.

Results

The guidance provides a deeper understanding of DMD and its variants, focusing on patient engagement, diagnostic criteria, natural history, biomarkers, and clinical trials. It underscores patient-focused drug development, the significance of dystrophin as a biomarker, and the pivotal role of magnetic resonance imaging in assessing disease progression. Additionally, the guidance addresses cardiomyopathy's prominence in DMD and the burgeoning field of gene therapy.

Conclusions

The updated guidance offers a comprehensive understanding of DMD, emphasizing patient-centric approaches, innovative trial designs, and the importance of biomarkers. The focus on cardiomyopathy and gene therapy signifies the evolving realm of DMD research. It acts as a crucial roadmap for sponsors, potentially leading to improved treatments for DMD.

Natural history of Duchenne muscular dystrophy in the United Kingdom: A descriptive study using the Clinical Practice Research Datalink

BACKGROUND

Duchenne muscular dystrophy (DMD) is a rare, muscle-degenerative disease predominantly affecting males. Natural history models capture the full disease pathway under current care and combine with estimates of new interventions' effects to assess cost-effectiveness by health technology decision-makers. These models require mortality estimates throughout a patient's lifetime, but rare disease datasets typically contain relatively few patients with short follow-ups. Alternative (published) sources of mortality data may therefore be required.

METHODS

The Clinical Practice Research Datalink (CPRD) was evaluated as a source of mortality and natural history data for future economic evaluations of health technologies for DMD and rare diseases in general in the UK population. This retrospective longitudinal cohort study provides flexible parametric estimates of mortality rates and survival probabilities in the current UK DMD population through primary/secondary records in the CPRD since 1990. It also investigates clinically significant milestones such as corticosteroid use, spinal surgery, and cardiomyopathy in these patients.

RESULTS

A total of 1121 male patients were included in the study, observed from 0.7 to 48.9 years. Median life expectancy was 25.64 years (95% confidence interval 24.73, 26.47), consistent with previous global estimates. This has improved to 26.47 (25.16, 27.89) years in patients born after 1990. The median ages at corticosteroid initiation, spinal surgery, ventilation, and cardiomyopathy diagnosis were 6.06 years (5.77, 6.29), 14.79 years (14.29, 15.09), 16.97 years (16.50, 18.31), and 15.26 years (14.22, 16.70), respectively.

CONCLUSIONS

Estimates of mortality in UK-based DMD patients are age-specific in a uniquely large and nationally representative sample from the CPRD.

A systematic literature review and meta-analysis of the effectiveness of vitamin D supplementation for patients with Duchenne muscular dystrophy

We conducted a systematic literature review and meta-analysis on the effectiveness of vitamin D supplementation in maintaining or restoring vitamin D levels in Duchenne muscular dystrophy. Due to a lack of randomised controlled trials, cross-sectional and retrospective and prospective cohort studies were taken as the best available evidence. Inclusion criteria included reporting mean serum vitamin D levels in a supplement-taking group. After screening 102 records; 13 were included in a narrative synthesis and eight of these in a meta-analysis. We show that current dosing regimens are preventing severe deficiency but are not effective at maintaining sufficient vitamin D levels within the Duchenne population. Despite high levels of daily vitamin D supplementation (>1000 International Units), at least 20 % of people with Duchenne remain vitamin D deficient. No significant association between dose and serum vitamin D levels was found (r2 = 0.3, p = 0.237). A meta-analysis of mean serum vitamin D levels across eight studies also revealed substantial variability in response to vitamin D supplementation and high heterogeneity (I2 = 99.59 %). These data could impact on an individual's risk and severity of osteoporosis and vertebral fractures.

Genetic Neuromuscular Disorders and Health Services Access, Utilization, and Needs in Zambia

BACKGROUND

Medical and rehabilitative advances increasingly transform management of rare genetic neuromuscular diseases (GNMDs) for children in the global north. Lack of information about GNMDs and related health care needs in sub-Saharan Africa threatens to widen pre-existing health disparities.

METHODS

This is a cross-sectional study of probands enrolling in a study of GNMDs at the University Teaching Hospital in Lusaka, Zambia, a member of the International Consortium for Genomic Medicine in Neuromuscular Disease. Probands/caregivers were interviewed about utilization of medical, rehabilitative, and other support services by a research assistant. A neuromuscular neurologist and/or physiotherapist examined each case and completed an independent questionnaire regarding health service utilization for each proband. Diagnoses were made on available clinical and electrophysiologic data. Molecular findings were unavailable at the time of this analysis.

RESULTS

Among 50 probands, 52% were male with median age 12 (absolute range 2 months to 54 years). Motor neuron diseases (n = 16; 32%), muscle disorders (n = 20; 40%), and inherited polyneuropathies (n = 5; 10%) were most common. Six (15%) cases had insufficient clinical data to classify the GNMDs. Outside of primary care, patient/caregiver-reported access to recommended health services (n = 34; 69%) was challenging. Large disparities in current utilization of health care services versus clinician-recommended services are reported.

CONCLUSIONS

Paradigms to improve access to diagnostics and therapeutic interventions are needed for GNMDs in Zambia. Multidisciplinary clinics may improve access and utilization of needed health services. Qualitative and other research focused on improving referrals, access, and quality of available health services are greatly needed.

Polysymptomatology and Polypharmacy at End of Life in Patients with Duchenne Muscular Dystrophy

OBJECTIVE

To characterize symptom frequency and symptom-directed treatment approaches in patients who died with advanced Duchenne muscular dystrophy (DMD).

STUDY DESIGN

This was a retrospective cohort study of patients in a multidisciplinary DMD program who died between January 1, 2013, and June 30, 2021. Inclusion criteria were patients who died with advanced DMD in the time period studied; exclusion criteria were low exposure to palliative care (<2 encounters). Demographic, symptom, and end-of-life data, as well as medications used for symptom management, were abstracted from the electronic medical record.

RESULTS

In total, 15 patients were eligible for analysis. The median age of death was 23 years (range 15-30 years). One (6.7%) experienced a full code at death, 8 (53.3%) had do-not-resuscitate orders, and 4 (26.7%) had limited do-not-resuscitate orders. Mean palliative care exposure was 1280 days. All 15 (100%) had pain and dyspnea; 14 (93.3%) anorexia, constipation, and sleep difficulty; 13 (86.7%) wounds; and 12 (80%) anxiety and nausea/vomiting. Multiple medications and drug classes were used to target symptoms.

CONCLUSIONS

We found significant polysymptomatology and polypharmacy in patients who died with advanced DMD. Clinicians who care for patients with advanced DMD should clarify goals of care and document advance care planning. Given the complexity of multisystem disease progression, palliative care should provide subspecialty pain management and assist with psychosocial burdens.

Role of CRISPR/Cas9 in the treatment of Duchenne muscular dystrophy and its delivery strategies

Duchenne muscular dystrophy (DMD) is a neuromuscular disorder brought on by mutations in the DMD gene, which prevent muscle cells from expressing the dystrophin protein. CRISPR/Cas9 technology has evolved as potential option to treat DMD due to its ability to permanently skip exons, restoring the disrupted DMD reading frame and leading to dystrophin restoration. Even though, having potential to treat DMD, the delivery, safety and efficacy of this technology is still challenging. Several delivery methods, including viral vectors, nanoparticles, and electroporation, have been explored to deliver CRISPR/Cas9 to the targeted cells. Despite the potential of CRISPR/Cas9 technology in the treatment of DMD, several limitations need to be addressed. The off-target effects of CRISPR/Cas9 are a major concern that needs to be addressed to avoid unintended mutations. The delivery of CRISPR/Cas9 to the target cells and the immune response due to the viral vectors used for delivery are a few other limitations. The clinical trials of CRISPR/Cas9 for DMD provide valuable insights into the safety and efficacy of this technology in humans and the limitations that need to be known. Therefore, in this review we insightfully discussed the challenges and limitations of CRISPR/Cas9 in the treatment of DMD and delivery strategies used, and the ongoing efforts to overcome these challenges and restore dystrophin expression in DMD patients in the ongoing trials.

Multidisciplinary Clinics in Neuromuscular Medicine

ABSTRACT

Multidisciplinary care is comprehensive, coordinated clinical care across medical disciplines and allied health professions. Neuromuscular disorders, such as amyotrophic lateral sclerosis and muscular dystrophies, are often associated with disabling weakness and extramuscular symptoms and may benefit from care in a model that consolidates numerous clinic visits into a single more efficient multidisciplinary clinic visit. The goal of the neuromuscular multidisciplinary care model is to improve patient outcomes, patient satisfaction, quality of life, access to medications and equipment, and survival. Although the costs of running a multidisciplinary clinic are high, they are likely associated with cost savings from the patient's perspective. Several barriers to acceptance of multidisciplinary clinics include the distance needed to travel to the clinic and the duration of the clinic visit. Telehealth multidisciplinary clinic visits may address some of these concerns. Further study is needed to understand the value of multidisciplinary clinics and is a necessary step toward creating a sustainable model.

Gastrointestinal and nutritional care in pediatric neuromuscular disorders

Neuromuscular diseases (NMDs) affect the development and growth of the neuromuscular system in children. The pathology can occur anywhere along the neuromuscular pathway, from the brain to the nerves to the muscle fibers. These diseases have a profound impact on the quality of life not only of children but also of their families. The predominant manifestation in NMDs is hypotonia, which leads to muscle weakness and fatigue, reduced mobility, and decreased physical performance. However, multiple organ systems can be affected, with resulting orthopedic, cardiac, infectious, respiratory, and nutritional problems. Children with NMD present an increased risk for several dietary and feeding difficulties because of their neuromuscular diagnosis, presentation, and severity. These problems include chronic gastrointestinal issues (constipation, dysphagia, gastroesophageal reflux, and diarrhea), dysphagia, malnutrition, and body composition alterations. As a result, compared to the overall pediatric population, infants and children with NMD are more likely to be malnourished, ranging from failure to thrive to overweight or obesity. Disease-specific guidelines vary in level of detail and recommendations for dietary management. Overall, nutritional data available are sparse, with the exception of Duchenne muscular dystrophy, spinal muscular atrophy, and congenital muscular dystrophy. The purpose of this review is to describe the spectrum of nutritional challenges in children with NMD and to summarize the main dietary and gastrointestinal recommendations for each neuromuscular disorder to provide guidance for daily clinical practice.

Identification of wheelchair seating criteria in adults with neuromuscular diseases: A Delphi study

BACKGROUND

Adults with neuromuscular diseases like spinal muscular atrophy or Duchenne muscular dystrophy require full-time use of a wheelchair (WC) and perform all activities of daily living in a sitting position. Optimal configuration of the WC and seating system is essential to maintain the health and quality of life of users. However, few recommendations for configuration exist. The aim of this study was to identify and select 10 WC seating criteria that ensure an optimal sitting posture for health and quality of life.

METHODS

A four round Delphi method was used to collect the opinions of WC users and health professionals (HP), separately. First, the HP were asked if they believed that different criteria would apply to each disease. Then the HP and SMA II and DMD WC user experts responded to electronic surveys in 4 rounds.

RESULTS

Overall, 74 experts took part: 31 HP, 21 WC users with SMA II and 22 WC users with DMD. In total, 52% of HP believed that different criteria would apply to each disease. Ten criteria were identified by the HP for SMA II and 10 for DMD. Of the 40 criteria selected, 30 (75%) were common to each panel. Six topics were similar across panels: comfort, access to the joystick, prevention of pain, stability, pressure management and power seat functions. However, power seat functions did not reach consensus between HP and WC users (30-33% of agreement for HP and 93-100% for the WC user panels, p < 0.001).

CONCLUSION

Adults with SMA II and DMD had similar WC seating needs. Therefore, the same recommendations can be applied to these groups. Further research is necessary to understand the impact of cost on the prescription of power seat functions by health professionals.

Real-world evidence of eteplirsen treatment effects in patients with Duchenne muscular dystrophy in the USA

Aim: To evaluate treatment effects of eteplirsen among patients with Duchenne muscular dystrophy. Methods: Using real-world claims and electronic medical record data, this retrospective comparative analysis assessed eteplirsen-treated and control cohorts matched by age, disease progression state, and pre-index period healthcare resource utilization. Poisson regression was used to evaluate eteplirsen effects on healthcare resource utilization outcomes. Results: Eteplirsen was associated with statistically significant reductions in rates of hospital encounters (31%), emergency room visits (31%), need for pulmonary management (33%), cardiac management (21%), tracheostomy (86%), and assisted ventilation (39%) versus the control group. Other assessed outcomes favored eteplirsen numerically but did not all reach statistical significance. Conclusion: Eteplirsen-treated patients had reduced rates of multiple healthcare resource utilization measures versus matched controls.

The role of lung volume recruitment therapy in neuromuscular disease: a narrative review

Respiratory muscle weakness results in substantial discomfort, disability, and ultimately death in many neuromuscular diseases. Respiratory system impairment manifests as shallow breathing, poor cough and associated difficulty clearing mucus, respiratory tract infections, hypoventilation, sleep-disordered breathing, and chronic ventilatory failure. Ventilatory support (i.e., non-invasive ventilation) is an established and key treatment for the latter. As survival outcomes improve for people living with many neuromuscular diseases, there is a shift towards more proactive and preventative chronic disease multidisciplinary care models that aim to manage symptoms, improve morbidity, and reduce mortality. Clinical care guidelines typically recommend therapies to improve cough effectiveness and mobilise mucus, with the aim of averting acute respiratory compromise or respiratory tract infections. Moreover, preventing recurrent infective episodes may prevent secondary parenchymal pathology and further lung function decline. Regular use of techniques that augment lung volume has similarly been recommended (volume recruitment). It has been speculated that enhancing lung inflation in people with respiratory muscle weakness when well may improve respiratory system "flexibility", mitigate restrictive chest wall disease, and slow lung volume decline. Unfortunately, clinical care guidelines are based largely on clinical rationale and consensus opinion rather than level A evidence. This narrative review outlines the physiological changes that occur in people with neuromuscular disease and how these changes impact on breathing, cough, and respiratory tract infections. The biological rationale for lung volume recruitment is provided, and the clinical trials that examine the immediate, short-term, and longer-term outcomes of lung volume recruitment in paediatric and adult neuromuscular diseases are presented and the results synthesised.

Duchenne muscular dystrophy in Italy: A systematic review of epidemiology, quality of life, treatment adherence, and economic impact

OBJECTIVE

This systematic review aims to update the evidence on Duchenne muscular dystrophy (DMD) in Italy, describing the epidemiology, quality of life (QoL) of patients and caregivers, treatment adherence, and economic impact of DMD.

METHODS

Systematic searches were conducted in PubMed, Embase and Web of Science up to January 2023. Literature selection process, data extraction and quality assessment were performed by two independent reviewers. Study protocol was registered in PROSPERO (CRD42021245196).

RESULTS

Thirteen studies were included. The prevalence of DMD in the general population is 1.7-3.4 cases per 100,000, while the birth prevalence is 21.7-28.2 per 100,000 live male births. The QoL of DMD patients and caregivers is lower than that of healthy subjects, and the burden for caregivers of DMD children is higher than that of caregivers of children with other neuromuscular disorders. The compliance of real-world DMD care to clinical guidelines recommendations in Italy is lower than in other European countries. The annual cost of illness for DMD in Italy is € 35,000-46,000 per capita while, adding intangible costs, the total cost amounts to € 70,000.

CONCLUSION

Although it is a rare disease, DMD represents a significant burden in terms of quality of life of patients and their caregivers, and economic impact.

Duchenne muscular dystrophy: disease mechanism and therapeutic strategies

Duchenne muscular dystrophy (DMD) is a severe, progressive, and ultimately fatal disease of skeletal muscle wasting, respiratory insufficiency, and cardiomyopathy. The identification of the dystrophin gene as central to DMD pathogenesis has led to the understanding of the muscle membrane and the proteins involved in membrane stability as the focal point of the disease. The lessons learned from decades of research in human genetics, biochemistry, and physiology have culminated in establishing the myriad functionalities of dystrophin in striated muscle biology. Here, we review the pathophysiological basis of DMD and discuss recent progress toward the development of therapeutic strategies for DMD that are currently close to or are in human clinical trials. The first section of the review focuses on DMD and the mechanisms contributing to membrane instability, inflammation, and fibrosis. The second section discusses therapeutic strategies currently used to treat DMD. This includes a focus on outlining the strengths and limitations of approaches directed at correcting the genetic defect through dystrophin gene replacement, modification, repair, and/or a range of dystrophin-independent approaches. The final section highlights the different therapeutic strategies for DMD currently in clinical trials.

The Importance of Implementing a Transition Strategy for Patients with Muscular Dystrophy: From Child to Adult-Insights from a Tertiary Centre for Rare Neurological Diseases

Progress in the field of muscular dystrophy (MD) using a multidisciplinary approach based on international standards of care has led to a significant increase in the life expectancy of patients. The challenge of transitioning from pediatric to adult healthcare has been acknowledged for over a decade, yet it continues to be a last-minute concern. Currently, there is no established consensus on how to evaluate the effectiveness of the transition process. Our study aimed to identify how well patients are prepared for the transition and to determine their needs. We conducted a descriptive, cross-sectional study on 15 patients aged 14 to 21 years. The patients completed a sociodemographic and a Transition Readiness Assessment Questionnaire (TRAQ). We also analyzed the comorbidities of these patients. Our study revealed that only 46.7% of the patients had engaged in a conversation with a medical professional, namely, a child neurologist, about transitioning. A total of 60% of the participants expressed having confidence in their self-care ability. However, the median TRAQ score of 3.6 shows that these patients overestimate themselves. We emphasize the necessity for a slow, personalized transition led by a multidisciplinary team to ensure the continuity of state-of-the-art care from pediatric to adult healthcare services and the achievement of the highest possible quality of life for these patients.

[Molecular therapies: present and future in neuromuscular diseases]

BACKGROUND

The possibilities in the field of molecular therapies of neuromuscular diseases have rapidly developed in recent years. First compounds are already available in clinical practice and numerous other substances are in advanced phases of clinical trials. This article gives an exemplary overview of the current state of clinical research in molecular therapies of neuromuscular diseases. It also gives a view into the near future of the clinical application, including the challenges.

DISCUSSION

Using Duchenne muscular dystrophy (DMD) and myotubular myopathy as examples, the principles of gene addition in monogenetic skeletal muscle diseases, which are already manifested in childhood are described. In addition to initial successes, the challenges and setbacks hindering the approval and regular clinical application of further compounds are demonstrated. Furthermore, the state of current clinical research in Becker-Kiener muscular dystrophy (BMD) and the numerous forms of limb-girdle muscular dystrophy (LGMD) are summarized. Numerous new therapeutic approaches and a corresponding outlook are also shown for facioscapulohumeral muscular dystrophy (FSHD), Pompe disease, and myotonic dystrophy.

CONCLUSION

Clinical research in the field of molecular therapy of neuromuscular diseases is one of the pacesetters of modern precision medicine; however, challenges need to be seen, jointly addressed and overcome in the future.

Microalgae Produce Antioxidant Molecules with Potential Preventive Effects on Mitochondrial Functions and Skeletal Muscular Oxidative Stress

In recent years, microalgae have become a source of molecules for a healthy life. Their composition of carbohydrates, peptides, lipids, vitamins and carotenoids makes them a promising new source of antioxidant molecules. Skeletal muscle is a tissue that requires constant remodeling via protein turnover, and its regular functioning consumes energy in the form of adenosine triphosphate (ATP), which is produced by mitochondria. Under conditions of traumatic exercise or muscular diseases, a high production of reactive oxygen species (ROS) at the origin of oxidative stress (OS) will lead to inflammation and muscle atrophy, with life-long consequences. In this review, we describe the potential antioxidant effects of microalgae and their biomolecules on mitochondrial functions and skeletal muscular oxidative stress during exercises or in musculoskeletal diseases, as in sarcopenia, chronic obstructive pulmonary disease (COPD) and Duchenne muscular dystrophy (DMD), through the increase in and regulation of antioxidant pathways and protein synthesis.

Safety and effectiveness of ataluren in patients with nonsense mutation DMD in the STRIDE Registry compared with the CINRG Duchenne Natural History Study (2015-2022): 2022 interim analysis

OBJECTIVE

Strategic Targeting of Registries and International Database of Excellence (STRIDE) is an ongoing, international, multicenter registry of real-world ataluren use in individuals with nonsense mutation Duchenne muscular dystrophy (nmDMD) in clinical practice. This updated interim report (data cut-off: January 31, 2022), describes STRIDE patient characteristics and ataluren safety data, as well as the effectiveness of ataluren plus standard of care (SoC) in STRIDE versus SoC alone in the Cooperative International Neuromuscular Research Group (CINRG) Duchenne Natural History Study (DNHS).

METHODS

Patients are followed up from enrollment for at least 5 years or until study withdrawal. Propensity score matching was performed to identify STRIDE and CINRG DNHS patients who were comparable in established predictors of disease progression.

RESULTS

As of January 31, 2022, 307 patients were enrolled from 14 countries. Mean (standard deviation [SD]) ages at first symptoms and at genetic diagnosis were 2.9 (1.7) years and 4.5 (3.7) years, respectively. Mean (SD) duration of ataluren exposure was 1671 (56.8) days. Ataluren had a favorable safety profile; most treatment-emergent adverse events were mild or moderate and unrelated to ataluren. Kaplan-Meier analyses demonstrated that ataluren plus SoC significantly delayed age at loss of ambulation by 4 years (p < 0.0001) and age at decline to %-predicted forced vital capacity of < 60% and < 50% by 1.8 years (p = 0.0021) and 2.3 years (p = 0.0207), respectively, compared with SoC alone.

CONCLUSION

Long-term, real-world treatment with ataluren plus SoC delays several disease progression milestones in individuals with nmDMD. NCT02369731; registration date: February 24, 2015.

Growth hormone secretagogues modulate inflammation and fibrosis in mdx mouse model of Duchenne muscular dystrophy

Introduction

Growth hormone secretagogues (GHSs) exert multiple actions, being able to activate GHS-receptor 1a, control inflammation and metabolism, to enhance GH/insulin-like growth factor-1 (IGF-1)-mediated myogenesis, and to inhibit angiotensin-converting enzyme. These mechanisms are of interest for potentially targeting multiple steps of pathogenic cascade in Duchenne muscular dystrophy (DMD).

Methods

Here, we aimed to provide preclinical evidence for potential benefits of GHSs in DMD, via a multidisciplinary in vivo and ex vivo comparison in mdx mice, of two ad hoc synthesized compounds (EP80317 and JMV2894), with a wide but different profile. 4-week-old mdx mice were treated for 8 weeks with EP80317 or JMV2894 (320 µg/kg/d, s.c.).

Results

In vivo, both GHSs increased mice forelimb force (recovery score, RS towards WT: 20% for EP80317 and 32% for JMV2894 at week 8). In parallel, GHSs also reduced diaphragm (DIA) and gastrocnemius (GC) ultrasound echodensity, a fibrosis-related parameter (RS: ranging between 26% and 75%). Ex vivo, both drugs ameliorated DIA isometric force and calcium-related indices (e.g., RS: 40% for tetanic force). Histological analysis highlighted a relevant reduction of fibrosis in GC and DIA muscles of treated mice, paralleled by a decrease in gene expression of TGF-β1 and Col1a1. Also, decreased levels of pro-inflammatory genes (IL-6, CD68), accompanied by an increment in Sirt-1, PGC-1α and MEF2c expression, were observed in response to treatments, suggesting an overall improvement of myofiber metabolism. No detectable transcript levels of GHS receptor-1a, nor an increase of circulating IGF-1 were found, suggesting the presence of a novel receptor-independent mechanism in skeletal muscle. Preliminary docking studies revealed a potential binding capability of JMV2894 on metalloproteases involved in extracellular matrix remodeling and cytokine production, such as ADAMTS-5 and MMP-9, overactivated in DMD.

Discussion

Our results support the interest of GHSs as modulators of pathology progression in mdx mice, disclosing a direct anti-fibrotic action that may prove beneficial to contrast pathological remodeling.

A systematic review and qualitative synthesis of the experiences of parents of individuals living with Duchenne muscular dystrophy

PURPOSE

Some parents of children with DMD find their role challenging, affecting quality of life. To inform support methods, we aimed to understand the lived experiences of parents and how these interact with disease progression.

MATERIALS AND METHODS

PRISMA informed protocol development. Qualitative and mixed methods studies were included. Four databases were searched and study quality was assessed using a standardised measure. Extracted data were analysed using thematic synthesis.

RESULTS

26 studies were included, comprising 362 parents. Seven descriptive themes were apparent: "Diagnostic Experiences", "Coping with the Caregiver Role", "Illness Trajectory and Associated Interventions", "Family Communication", "Network of Support", "Navigating Systems" and "Transition Experiences". Four analytical themes were then derived: "The Cyclical Nature of Grief", "Lifelong Expert in the Needs and Experiences of an Individual with DMD", "Navigating Deviation from Typical Life Course" and "Uncertainty as Ever Present".

CONCLUSION

The extant evidence suggests that the experience of parenting a child with DMD is often characterised by: a cycle of grief that begins at diagnosis, which runs parallel to the development of expertise in caregiving; within this parents notice deviations from their child's and their own expected life course and adjust to the emotions and uncertainty that this can bring.IMPLICATIONS FOR REHABILITATIONProfessionals should be cognisant to the complex grief process associated with DMD, which occurs from diagnosis onwards.There should be continued support for parents following bereavement.Peer support groups may also offer parents ways to maintain well-being.The necessity for parents to function effectively within an uncertain context that induces challenging emotions suggests a role for psychological therapies.

Efficacy and Safety of Viltolarsen in Boys With Duchenne Muscular Dystrophy: Results From the Phase 2, Open-Label, 4-Year Extension Study

Background: Duchenne muscular dystrophy (DMD) is caused by DMD gene mutations, resulting in absence of functional dystrophin protein. Viltolarsen, an exon 53 skipping therapy, significantly increased dystrophin levels in patients with DMD. Presented here are completed study results of >4 years of functional outcomes in viltolarsen-treated patients compared to a historical control group (Cooperative International Neuromuscular Research Group Duchenne Natural History Study [CINRG DNHS]). Objective: To evaluate the efficacy and safety of viltolarsen for an additional 192 weeks in boys with DMD. Methods: This phase 2, open-label, 192-week long-term extension (LTE) study (NCT03167255) evaluated the efficacy and safety of viltolarsen in participants aged 4 to <10 years at baseline with DMD amenable to exon 53 skipping. All 16 participants from the initial 24-week study enrolled into this LTE. Timed function tests were compared to the CINRG DNHS group. All participants received glucocorticoid treatment. The primary efficacy outcome was time to stand from supine (TTSTAND). Secondary efficacy outcomes included additional timed function tests. Safety was continuously assessed. Results: For the primary efficacy outcome (TTSTAND), viltolarsen-treated patients showed stabilization of motor function over the first two years and significant slowing of disease progression over the following two years compared with the CINRG DNHS control group which declined. Viltolarsen was well tolerated, with most reported treatment-emergent adverse events being mild or moderate. No participants discontinued drug during the study. Conclusions: Based on the results of this 4-year LTE, viltolarsen can be an important treatment strategy for DMD patients amenable to exon 53 skipping.

'Our time is precious': An exploration of parental feeding behaviours for boys with Duchenne muscular dystrophy

INTRODUCTION

Due to the increased risk of obesity for boys with Duchenne muscular dystrophy (DMD), recent guidelines recommend that dietary intake is carefully managed. Parents play an important role in the development of their child's eating behaviours and patterns. However, despite what is known about the increased risk of obesity for children with DMD, little is known about parental feeding behaviours in this population. The objective of this study was to qualitatively explore the experiences of parents of children with DMD around their child's weight management and understand what influences their feeding behaviours.

METHODS

This paper reports a secondary data analysis. Semi-structured, individual interviews were conducted and analysed using qualitative description.

RESULTS

Thirteen parents were interviewed for the study. Three themes were developed: (1) parent responses to healthcare provider interactions, (2) mixed emotions contributing to feeding approach and (3) variable parenting feeding styles. Within the third theme, two subthemes arose including (1) control and preoccupation and (2) striking a balance.

CONCLUSION

Given the potential impact of higher weights on the progression of DMD, it is important that healthcare providers explore feeding behaviours with families. However, it is essential that healthcare providers consider the impact of these conversations on parents, as well as the broader issues that may place additional pressure on the lives of families.

Heteroaromatic Diazirines Are Essential Building Blocks for Material and Medicinal Chemistry

In materials (polymer) science and medicinal chemistry, heteroaromatic derivatives play the role of the central skeleton in development of novel devices and discovery of new drugs. On the other hand, (3-trifluoromethyl)phenyldiazirine (TPD) is a crucial chemical method for understanding biological processes such as ligand-receptor, nucleic acid-protein, lipid-protein, and protein-protein interactions. In particular, use of TPD has increased in recent materials science to create novel electric and polymer devices with comparative ease and reduced costs. Therefore, a combination of heteroaromatics and (3-trifluoromethyl)diazirine is a promising option for creating better materials and elucidating the unknown mechanisms of action of bioactive heteroaromatic compounds. In this review, a comprehensive synthesis of (3-trifluoromethyl)diazirine-substituted heteroaromatics is described.

Coexistence of a Heterozygous Caveolin-3 Deletion and a Novel Dystrophin Gene Mutation in a Duchenne Muscular Dystrophy Patient

Inherited muscular abnormalities are debilitating disorders that greatly diminish the quality of life in affected individuals. Mutations in proteins such as dystrophin and caveolin, which together with other proteins form structural connections between the cytoskeleton and the extracellular matrix, are frequently the culprit of muscular dystrophies. In this case report, we describe a patient with a novel pathogenic dystrophin mutation co-existing with a caveolin-3 deletion. While genetically composed of this unique combination, the patient phenotypically presented with a primary clinical manifestation of Duchenne muscular dystrophy (DMD) in contrast to other cases of dual mutations in dystrophin and dystrophin-associated proteins.

Perks of Rehabilitation in Improving Motor Function in a Nine-Year-Old Male With Duchenne Muscular Dystrophy: A Case Report

Duchenne muscular dystrophy (DMD) is a progressive disorder. It is the most typical X-linked muscular dystrophy in children. It primarily affects males and is characterized by motor delays, muscle weakness, respiratory impairment, and loss of ambulation. A case study of a nine-year-old male diagnosed with DMD is presented. The patient had difficulty walking since the age of four and had a proximal lower extremity weakness on both sides previously with a reduced range of motion (ROM). For the last 15 days, the patient is unable to walk and has hypotonia in both lower limbs. The diagnostic Gowers sign was positive. Balance and mobility were affected. Treatment of this patient is focused mostly on maintaining the range of motion (ROM), respiratory training, and balance.

Current care practices for patients with Duchenne muscular dystrophy in China

BACKGROUND

The coronavirus disease (COVID-19) pandemic has presented challenges in the care of patients with chronic diseases. We identified the challenges faced by Chinese patients with Duchenne muscular dystrophy (DMD) during the pandemic.

METHODS

An online cross-sectional survey was conducted between March 27 and June 30, 2021.

RESULTS

Of the 2105 valid questionnaire responses, 2,056 patients were from non-lockdown areas. In these areas, 42.8% reduced outside daily activities, 49.4% reduced rehabilitation service use, 39.7% postponed regular follow-ups, and 40.8% reported accelerated motor function decline. These figures generally increased for patients from lockdown areas-67.3% reduced outside daily activities, 44.9% reduced rehabilitation service use, 79.6% postponed regular follow-ups, and 55.1% reported accelerated motor function decline. Ambulation loss was most commonly reported in September and March before 2020; however, this trend was absent in 2020. Regarding the informed prices of disease-modifying drugs in Europe and the United States, 86.7% could afford a maximum of one-twentieth of the prices, 8.0% could afford one-tenth of the prices, and only 0.6% of the patients could afford the full prices.

CONCLUSIONS

Implementation of standardized care for DMD in China is consistent with global practices, and the COVID-19 pandemic has affected the care of patients with chronic diseases worldwide, particularly in lockdown areas. Telemedicine is an effective model for providing healthcare to such patients. Healthcare workers should assist patients and establish more robust chronic disease management systems. Collaboration between governmental and non-governmental entities could address the cost of disease-modifying drugs in China and other developing countries.

In vivo restoration of dystrophin expression in mdx mice using intra-muscular and intra-arterial injections of hydrogel microsphere carriers of exon skipping antisense oligonucleotides

Duchenne muscular dystrophy (DMD) is a genetic disease caused by a mutation in the X-linked Dytrophin gene preventing the expression of the functional protein. Exon skipping therapy using antisense oligonucleotides (AONs) is a promising therapeutic strategy for DMD. While benefits of AON therapy have been demonstrated, some challenges remain before this strategy can be applied more comprehensively to DMD patients. These include instability of AONs due to low nuclease resistance and poor tissue uptake. Delivery systems have been examined to improve the availability and stability of oligonucleotide drugs, including polymeric carriers. Previously, we showed the potential of a hydrogel-based polymeric carrier in the form of injectable PEG-fibrinogen (PF) microspheres for delivery of chemically modified 2'-O-methyl phosphorothioate (2OMePs) AONs. The PF microspheres proved to be cytocompatible and provided sustained release of the AONs for several weeks, causing increased cellular uptake in mdx dystrophic mouse cells. Here, we further investigated this delivery strategy by examining in vivo efficacy of this approach. The 2OMePS/PEI polyplexes loaded in PF microspheres were delivered by intramuscular (IM) or intra-femoral (IF) injections. We examined the carrier biodegradation profiles, AON uptake efficiency, dystrophin restoration, and muscle histopathology. Both administration routes enhanced dystrophin restoration and improved the histopathology of the mdx mice muscles. The IF administration of the microspheres improved the efficacy of the 2OMePS AONs over the IM administration. This was demonstrated by a higher exon skipping percentage and a smaller percentage of centered nucleus fibers (CNF) found in H&E-stained muscles. The restoration of dystrophin expression found for both IM and IF treatments revealed a reduced dystrophic phenotype of the treated muscles. The study concludes that injectable PF microspheres can be used as a carrier system to improve the overall therapeutic outcomes of exon skipping-based therapy for treating DMD.

Cardiac and Pulmonary Management Status of Duchenne Muscular Dystrophy in South Korea Based on Data From the National Health Insurance Database

Background and Purpose

The purpose of this study was to determine the cardiac and pulmonary management status of patients with Duchenne muscular dystrophy (DMD) in South Korea based on the Korean National Health Insurance database.

Methods

This study used data of patients with code G71.0 in the National Health Information database, and also those with the special case of code V012. Cardiac function was assessed based on whether echocardiography and 24-h electrocardiography were performed, as well as the frequency of these investigations. Furthermore, information on the use of angiotensin-converting enzyme inhibitors (ACEi), angiotensin II receptor blockers (ARB), and beta blockers (BB) in the drug benefit list was checked. Medical charge records were also checked regarding the prescription of respiratory functional assessments and treatments.

Results

The diagnostic criteria were met by 479 patients, with 41% of these patients receiving a cardiac evaluation, 29.8% being prescribed ACEi at 14.4±3.7 years of age, 59.5% undergoing pulmonary function tests, and 42.1% received pulmonary rehabilitation. The age at receiving ventilator support was 19.4±2.7 years. The frequency of cardiac and respiratory function tests increased with age, but the interval between tests was longer than the recent DMD care recommendations. The trend of taking ACEi, ARB, and BB for cardiac management in South Korea did not change during the study analysis period.

Conclusions

The findings of this study will contribute to recognizing the current status and the importance of applying an anticipatory approach to cardiopulmonary function in DMD patients.

Bioenergetic and Metabolic Impairments in Induced Pluripotent Stem Cell-Derived Cardiomyocytes Generated from Duchenne Muscular Dystrophy Patients

Duchenne muscular dystrophy (DMD) is caused by mutations in the dystrophin gene and dilated cardiomyopathy (DCM) is a major cause of morbidity and mortality in DMD patients. We tested the hypothesis that DCM is caused by metabolic impairments by employing induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) generated from four DMD patients; an adult male, an adult female, a 7-year-old (7y) male and a 13-year-old (13y) male, all compared to two healthy volunteers. To test the hypothesis, we measured the bioenergetics, metabolomics, electrophysiology, mitochondrial morphology and mitochondrial activity of CMs, using respirometry, LC–MS, patch clamp, electron microscopy (EM) and confocal microscopy methods. We found that: (1) adult DMD CMs exhibited impaired energy metabolism and abnormal mitochondrial structure and function. (2) The 7y CMs demonstrated arrhythmia-free spontaneous firing along with “healthy-like” metabolic status, normal mitochondrial morphology and activity. In contrast, the 13y CMs were mildly arrhythmogenic and showed adult DMD-like bioenergetics deficiencies. (3) In DMD adult CMs, mitochondrial activities were attenuated by 45–48%, whereas the 7y CM activity was similar to that of healthy CMs. (4) In DMD CMs, but not in 7y CMs, there was a 75% decrease in the mitochondrial ATP production rate compared to healthy iPSC-CMs. In summary, DMD iPSC-CMs exhibit bioenergetic and metabolic impairments that are associated with rhythm disturbances corresponding to the patient’s phenotype, thereby constituting novel targets for alleviating cardiomyopathy in DMD patients.