The burden, epidemiology, costs and treatment for Duchenne muscular dystrophy: an evidence review

Comparison of surgical and non-surgical treatment for scoliosis in Duchenne muscular dystrophy: a systematic review and meta-analysis

INTRODUCTION

Duchenne muscular dystrophy (DMD) is a neuromuscular disease caused by dystrophin gene mutations, which not only causes severe physical and psychological damage to the patient but also imposes a considerable economic burden on society. However, whether to aggressively surgical treatment for progressive scoliosis of DMD remains a conundrum. Therefore, we aimed to systematically evaluate the efficacy and prognosis of surgical treatment for DMD-associated scoliosis.

MATERIALS AND METHODS

PubMed, Embase, The Cochrane Library, China National Knowledge Infrastructure database, Wanfang database, China Science and Technology Journal Database, and China Biomedical Literature Database were searched for literature from the time of database creation until November 2022. The inclusion parameters were as follows: number of survivors, frequency of complications, preoperative, postoperative, and final follow-up Cobb's angles. Data were analyzed using RevMan 5.4.1 and Stata 12.0.

RESULTS

Six studies were analyzed. Survival rates were higher [OR = 3.83, 95% CI (1.91, 7.66), p = 0.0001] and Cobb's angle improved [SMD, 1.79, 95% CI (150, 2.07), p < 0.00001] in the surgical group than in the non-surgical group. The non-surgical group had a lower complication rate than the surgical group did [OR = 8.75, 95% CI (1.02,75.08), p = 0.048].

CONCLUSIONS

Notably, scoliosis-correction surgery improves patient survival. Besides, scoliosis-correction surgery provides patients with more stable Cobb angle. As expected, non-surgical treatment has the advantage of reducing the occurrence of complications.

Physical activity and cardiac function in patients with Duchenne muscular dystrophy

BACKGROUND

Cardiomyopathy is the leading cause of death in patients with Duchenne muscular dystrophy. The relationship between cardiac and skeletal muscle progression is unclear. The objective of this study was to evaluate the correlation between muscle activity and cardiomyopathy. We hypothesised that cardiomyopathy and skeletal muscle activity are directly related.

METHODS

Physical activity was assessed with accelerometers worn for 7 days. Average activity (vector magnitude/min) and percentage of time in different activities were reported. Cardiac MRI was used to assess left ventricular ejection fraction, global circumferential strain (Ecc), late gadolinium enhancement, and cardiac index. Associations were assessed between physical activity and cardiac variables using a Spearman correlation.

RESULTS

Duchenne muscular dystrophy subjects (n = 46) with an average age of 13 ± 4 years had a mean left ventricular ejection fraction of 57 ± 8%. All physical activity measures showed significant correlations with left ventricular ejection fraction (rho = 0.38, p = 0.01) and left ventricular cardiac index (rho = 0.51, p < 0.001). Less active subjects had lower left ventricular ejection fraction (p = 0.10) and left ventricular cardiac index (p < 0.01). Non-ambulatory patients (n = 29) demonstrated a stronger association between physical activity and left ventricular ejection fraction (rho = 0.40, p = 0.03) while ambulatory patients demonstrated a stronger association between physical activity and left ventricular cardiac index (rho = 0.53, p = 0.03). Ecc did not associate with physical activity in either cohort.

CONCLUSION

Physical activity correlates with left ventricular ejection fraction and left ventricular cardiac index and is modified by ambulation. Future analysis should assess the temporal relationship between physical activity and cardiomyopathy.

The impact of rare diseases on the quality of life in paediatric patients: current status

Rare diseases, also known as orphan diseases, are a group of disorders that affect a small percentage of the population. Despite individually affecting a small number of people, collectively, they impact millions worldwide. This is particularly significant in paediatric patients, highlighting the global scale of the issue. This review delves into the exact prevalence of rare diseases among children and adolescents and their diverse impact on the quality of life of patients and their families. The review sheds light on the complex interplay of genetic and environmental factors contributing to these conditions and the diagnostic challenges and delays often encountered in identifying and categorising these diseases. It is noted that although there have been significant strides in the field of genomic medicine and the development of orphan drugs, effective treatments remain limited. This necessitates a comprehensive, multidisciplinary approach to management involving various specialities working closely together to provide holistic care. Furthermore, the review addresses the psychosocial and economic burdens faced by families with paediatric patients suffering from rare diseases, highlighting the urgent need for enhanced support mechanisms. Recent technological and therapeutic advancements, including genomic sequencing and personalized medicine, offer promising avenues for improving patient outcomes. Additionally, the review underscores the role of policy and advocacy in advancing research, ensuring healthcare access, and supporting affected families. It emphasises the importance of increased awareness, education, and collaboration among healthcare providers, researchers, policymakers, and patient advocacy groups. It stresses the pivotal role each group plays in improving the diagnosis, treatment, and overall quality of life for paediatric patients with rare diseases.

Automated analysis of quantitative muscle MRI and its reliability in patients with Duchenne muscular dystrophy

BACKGROUND

Quantitative muscle MRI is one of the most promising biomarkers to detect subclinical disease progression in patients with neuromuscular disorders, including Duchenne muscular dystrophy (DMD). However, its clinical application has been limited partly due to the time-intensive process of manual segmentation.

OBJECTIVE

We present a simple and fast automated approach to obtain quantitative measurement of thigh muscle fat fraction and investigate its reliability in patients with DMD.

METHODS

Clinical and radiological baseline and 6-month follow-up data of 41 ambulant patients with DMD were analysed retrospectively. Axial 2-point Dixon MR images of all thigh muscles were used to quantify mean fat fraction, while clinical outcomes were measured by the Motor Function Measure (MFM) and its D1 domain. Data obtained by automated segmentation were compared to manual segmentation and correlated with clinical outcomes. Results were also used to compare the statistical power when using automated or manual segmentation.

RESULTS

A mean increase of 3.55% in thigh muscle fat fraction at 6-month follow-up could be detected by both methods without any significant difference between them (p=0.437). The automated muscle segmentation method demonstrated a strong correlation with manually segmented data (Pearson's ρ = 0.97). Additionally, there was no statistically significant difference between the automated and manual segmentation methods in their association with clinical progression, as measured by the total MFM score and its D1 domain (p = 0.235 and p = 0.425, respectively).

CONCLUSIONS

The presented automated segmentation technique is a fast and reliable tool for assessing disease progression, particularly in the early stages of DMD. It is one of the few studies validated using manual segmentation, and with further refinement, it has the potential to become a good surrogate marker for disease progression in various neuromuscular disorders.

AOC 1044 induces exon 44 skipping and restores dystrophin protein in preclinical models of Duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD) is a severe disorder caused by mutations in the dystrophin gene, resulting in loss of functional dystrophin protein in muscle. While phosphorodiamidate morpholino oligomers (PMOs) are promising exon-skipping therapeutics aimed at restoring dystrophin expression, their effectiveness is often limited by poor muscle delivery. We developed AOC 1044, an antibody-oligonucleotide conjugate (AOC) that combines a PMO-targeting exon 44 with an antibody against the transferrin receptor (TfR1), enhancing delivery to muscle tissues for patients with DMD amenable to exon 44 skipping (DMD44). AOC 1044 induces dose-dependent exon 44 skipping and its mouse-active variant elicited dose-dependent dystrophin restoration in skeletal and cardiac muscle in a DMD mouse model. This treatment also reduced muscle damage, as evidenced by decreases in serum creatine kinase and key liver enzymes, suggesting that restored dystrophin is functionally active. In nonhuman primates, single or repeated AOC 1044 doses resulted in dose-dependent increases in PMO concentration and exon 44 skipping across a range of muscle tissues, including the heart. Collectively, these findings highlight AOC 1044 as a promising therapeutic candidate for patients with DMD44, offering improved muscle targeting and meaningful dystrophin restoration, with potential clinical benefits in reducing muscle degeneration.

Visualizing ambulatory performance by age and rates of decline among patients with Duchenne muscular dystrophy

In Duchenne muscular dystrophy (DMD), age at symptom onset and rate of decline thereafter vary considerably. This study contrasted disease progression over time using the North Star Ambulatory Assessment (NSAA) in an overall sample of patients with DMD (mean age 7.1 years; baseline total NSAA score 22.2) with that of a centrally representative subgroup (mean age 6.9 years; NSAA score 24.0) defined according to median age at loss of ambulation. The average disease trajectory in the overall sample understated the more rapid rates of decline experienced by patients in the centrally representative subgroup.

A Hypothesized Therapeutic Role of (Z)-Endoxifen in Duchenne Muscular Dystrophy (DMD)

Duchenne Muscular Dystrophy (DMD) is an inherited, X-linked disorder that is progressive, debilitating, and ultimately fatal. The current therapeutic landscape offers no cures, but does include palliative treatments that delay disease progression, and there is progress on genetic therapies that have the promise to be curative. There is much room for new therapies, and foundational work with the estrogen receptor modulator tamoxifen suggests the potential of a unique spectrum of therapeutic benefit from endoxifen, a metabolite of tamoxifen. Here we describe the potential for this new DMD therapy in the context of the overall DMD therapeutic landscape.

A patient-centered qualitative evaluation of meaningful change on the NSAA and PUL in Duchenne Muscular Dystrophy

Background

Duchenne Muscular Dystrophy (DMD) is a rare X-linked genetic disorder caused by mutations in the dystrophin gene. The North Star Ambulatory Assessment (NSAA) and Performance of Upper Limb (PUL) are used to measure motor performance in ambulatory and non-ambulatory individuals, respectively. There is limited published qualitative evidence on what constitutes a meaningful change on either instrument. The aim of this study is to understand meaningful change in functional abilities as measured by the NSAA and PUL at different ability levels from the perspective of individuals with DMD, caregivers of individuals with DMD, and clinicians.

Methods

The study utilized a non-interventional, descriptive, cross-sectional qualitative design consisting of 69 semi-structured interviews, including individuals with DMD (n = 18), caregivers of individuals with DMD (n = 51), and neuromuscular physiotherapists (n = 2) to understand meaningful change on the NSAA and PUL.

Results

The results for both instruments indicated that: (i) items that are meaningful differ based on ability level; (ii) maintaining function in lower and upper limbs is the ultimate goal; (iii) meaningful change is often reported in relation to gain or loss of specific function, as opposed to number of total points on the scale; and (iv) losing one scale point corresponds to either a partial or full loss in function and activity, which has differing impacts on daily life.

Conclusion

The perception of meaningful change in DMD as measured by the NSAA is influenced by ability levels and ambulatory function, with participants describing their need to maximize certain abilities, maintain function, and retain independence. For the PUL, participants underscored the importance of maintenance of their functional abilities, and highlighted key themes related to maintaining independence in ADLs, reaching, eating/drinking, and finger function for technology use across score categories.

Asymmetric Myocardial Involvement as an Early Indicator of Cardiac Dysfunction in Pediatric Dystrophinopathies: A Study on Cardiac Magnetic Resonance (CMR) Parametric Mappings

Dystrophinopathies, such as Duchenne and Becker muscular dystrophy, frequently lead to cardiomyopathy, being its primary cause of mortality. Detecting cardiac dysfunction early is crucial, but current imaging methods lack insight into microstructural remodeling. This study aims to assess the potential of cardiac magnetic resonance (CMR) parametric mappings for early detection of myocardial involvement in dystrophinopathies and explores whether distinct involvement patterns may indicate impending dysfunction. In this prospective study, 23 dystrophinopathy patients underwent CMR with tissue mappings. To establish a basis for comparison, a control group of 173 subjects was analyzed. CMR protocols included SSFP, T2-weighted and T1-weighted sequences pre and post gadolinium, and tissue mappings for native T1 (nT1), extracellular volume (ECV), and T2 relaxation times. The difference between the left ventricular posterior wall and the interventricular septum was calculated to reveal asymmetric myocardial involvement. Significant differences in LV ejection fraction (LVEF), myocardial mass, and late gadolinium enhancement confirmed abnormalities in patients. Tissue mappings: nT1 (p < 0.001) and ECV (p = 0.002), but not T2, displayed substantial variations, suggesting sensitivity to myocardial involvement. Asymmetric myocardial involvement in nT1 (p = 0.01) and ECV (p = 0.012) between septal and LV posterior wall regions was significant. While higher mapping values didn't correlate with dysfunction, asymmetric involvement in nT1 (ρ=-0.472, p = 0.023) and ECV (ρ=-0.460, p = 0.049) exhibited a significant negative correlation with LVEF. CMR mappings show promise in early myocardial damage detection in dystrophinopathies. Although mapping values may not directly correspond to dysfunction, the negative correlation between asymmetric involvement in nT1 and ECV with LVEF suggests their potential as early biomarkers. Larger, longitudinal studies are needed for a comprehensive understanding and improved risk stratification in dystrophinopathies.

BMN 351-Induced Exon Skipping and Dystrophin Expression in Skeletal and Cardiac Muscle Lead to Preservation of Motor Function in a Mouse Model of Exon 51 Skip-Amenable Duchenne Muscular Dystrophy

Duchenne muscular dystrophy (DMD) is caused by mutations of the DMD gene that prevent the expression of functional dystrophin protein. BMN 351 is an antisense oligonucleotide (ASO) designed to induce skipping of exon 51 of dystrophin pre-mRNA and production of internally deleted but functional dystrophin. We determined whether extended-term BMN 351 dosing leads to exon skipping, dystrophin production, and improved motor function in hDMDdel52/mdx mice containing a human exon 52-deleted DMD transgene. Weekly intravenous doses of vehicle, 6 mg/kg BMN 351, or 18 mg/kg BMN 351 were administered for 25 weeks, and samples were analyzed 4 and 12 weeks post-dosing. BMN 351 produced dose-dependent exon skipping levels in the heart and quadriceps muscles, accompanied by dose-dependent increases in mean dystrophin levels of 17% to 55% 12 weeks post-dosing. Compared with vehicle-treated hDMDdel52/mdx mice, BMN 351 ameliorated DMD-related histopathologic changes in the gastrocnemius muscle and heart. Both BMN 351 doses preserved fine motor kinematics, which was worse in vehicle-treated hDMDdel52/mdx mice compared with wild-type 4 and 12 weeks post-dosing. Liver samples demonstrated findings consistent with ASO accumulation, to which mice are considered especially sensitive compared to humans and other non-clinical species. These results support further non-clinical and clinical development of BMN 351.

Targeting a Novel Site in Exon 51 with Antisense Oligonucleotides Induces Enhanced Exon Skipping in a Mouse Model of Duchenne Muscular Dystrophy

Exon skipping with antisense oligonucleotides (ASOs) can correct disease-causing mutations of Duchenne muscular dystrophy (DMD) through RNA-targeted splice correction. This correction restores the reading frame and supports expression of near full-length dystrophin. First-generation exon 51-skipping ASOs targeted the same binding site, with limited clinical efficacy. We characterized a novel binding site within exon 51 that induced highly efficient exon skipping. A precursor ASO (AON-C12) and clinical ASO (BMN 351) were designed using 2'-O-methyl-modified phosphorothioate (2'OMePS) RNA and locked nucleic acids. hDMDdel52/mdx mice were given AON-C12 or BMN 351 for 13 weeks and evaluated for molecular and phenotypic correction of dystrophin deficiency. BMN 351 treatment induced durable, dose-dependent levels of exon skipping and dystrophin production in all muscles evaluated. In the heart, 8 weeks after the last BMN 351 dose at 18 mg/kg, exon-skipped transcripts remained at 44.3% of total, and dystrophin levels were 21.8% of wild type. BMN 351 reached higher tissue concentrations and percent exon skipping in the heart than a clinically relevant peptide-conjugated phosphorodiamidate morpholino oligomer comparator. BMN 351 also improved gait scores and clinical and anatomical muscle pathology parameters compared with vehicle-treated hDMDdel52/mdx mice. The pharmacologic activity and safety of BMN 351 warrant further nonclinical and clinical development.

The latest developments in synthetic approaches to Duchenne muscular dystrophy

INTRODUCTION

Duchenne muscular dystrophy (DMD) is a rare X-linked genetic disorder caused by mutations in the dystrophin gene, leading to an almost complete absence of dystrophin, which is essential for muscle cell structure and function. This resulting muscle deterioration and fibrosis, eventually causes respiratory failure and cardiomyopathy. While there is currently no cure, existing therapies aim to prolong survival and alleviate symptoms.

AREAS COVERED

This paper reviews current and emerging therapies for DMD, focusing on their safety and efficacy. Although corticosteroids remain the standard treatment, newly approved drugs such as exon-skipping therapies, vamorolone, delandistrogene moxeparvovec, and givinostat provide new treatment options. Additionally, future therapies, including gene therapy, stem cell treatments, and anti-fibrotic agents, show promise for clinical application.

EXPERT OPINION

Advancements in DMD treatments have expanded patient options. While gene therapy offers potential for correcting the genetic defect and alleviating symptoms, corticosteroids remain the most cost-effective and well-researched treatment. This is partly due to the lack of compelling long-term safety and efficacy data for gene therapies. The accelerated FDA review process has enabled faster approval of new medications; however many have provided minimal clinical benefit to patients. Despite these challenges, continued drug development and innovative research offer hope to patients.

Upper body gait deviations in children with Duchenne muscular dystrophy

BACKGROUND

Duchenne muscular dystrophy is primarily a disease of progressive muscle degeneration affecting the whole body. It is important to preserve the patients' walking ability as long as possible. Inconclusive information on Duchenne muscular dystrophy gait pattern is available for the lower body and missing for the upper body. This study aimed to objectively investigate upper body gait deviations in a group of patients with Duchenne muscular dystrophy compared to typically developing peers.

METHODS

Kinematic data of twelve boys with Duchenne muscular dystrophy that underwent three-dimensional full-body gait analysis were investigated retrospectively. Data were compared to sixteen healthy children of same age at similar walking speed. Statistical tests included the student independent t-test (with Holm-Bonferroni correction), Hedges'g for effect size, and statistical non-parametric mapping two-sample t-test (with Bonferroni correction).

FINDINGS

Duchenne muscular dystrophy compared to the healthy group: In the sagittal plane, the thorax segment was more posteriorly tilted. In addition, the relative angle between pelvis and thorax segment showed more backwards lean with increased shoulder extension. In the frontal plane, the patients walked with increased shoulder abduction and took wider strides. In the transverse plane, thorax rotation was not different between groups. Thorax range of motion was increased in all three planes.

INTERPRETATION

Including the upper body gait kinematics, especially of the trunk, adds valuable objective information on the understanding of the Duchenne muscular dystrophy gait pattern. Our findings contribute to improved understanding of full-body gait compensations in this patient group.

A Dual Diagnosis of Okur-Chung Neurodevelopmental Syndrome and Becker Muscular Dystrophy: Inquiry Into the Lower Limits of Neurodevelopmental Functioning Attributable to Muscular Dystrophy

PURPOSE

This case discusses the limits of neurodevelopmental functioning attributable to Duchenne's Muscular Dystrophy (DMD) dysfunction.

METHOD

A 3-year-old male presented with global developmental delay, growth failure, and dysmorphic facial features. An SNP microarray revealed an interstitial duplication in exon 55 of DMD suggestive of Becker Muscular Dystrophy (BMD), but his degree of delays led to follow-up exome sequencing revealing a pathogenic CSNK2A1 variant diagnostic for Okur-Chung Neurodevelopmental Syndrome.

FINDINGS

Large cohorts predict a full-scale IQ (FSIQ) of 88.3 ± 13.9 among all patients with BMD and 86.1 ± 15.0 among all patients with DMD, while variants impacting the brain dystrophin isoform Dp140 are associated with FSIQ of 77.7 ± 10.8 in BMD and 78.8 ± 18.6 in DMD.

CONCLUSION

An FSIQ one standard deviation below these expected ranges should prompt screening for alternative causes of neurodevelopmental delays, and an FSIQ two standard deviations below these ranges should prompt broad-spectrum genetic testing.

Phase 1/2 trial of brogidirsen: Dual-targeting antisense oligonucleotides for exon 44 skipping in Duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD) is a severe muscle disorder caused by mutations in the DMD gene, leading to dystrophin deficiency. Antisense oligonucleotide (ASO)-mediated exon skipping offers potential by partially restoring dystrophin, though current therapies remain mutation specific with limited efficacy. To overcome those limitations, we developed brogidirsen, a dual-targeting ASO composed of two directly connected 12-mer sequences targeting exon 44 using phosphorodiamidate morpholino oligomers. An open-label, dose-escalation, phase 1/2 trial assessed the safety, pharmacokinetics, and efficacy of brogidirsen in six ambulant patients with DMD amenable to exon 44 skipping. Following dose escalation, extended 24-week treatment with 40 mg/kg and 80 mg/kg yielded dose-dependent increases in dystrophin (16.63% and 24.47% of normal). Functional assessments indicated motor stabilization, and plasma proteomics revealed reductions in peptidyl arginine deiminase 2 (PADI2), titin (TTN), and myomesin 2 (MYOM2), highlighting potential biomarkers. Brogidirsen's efficacy was supported in vitro using urine-derived cells from patients with DMD. These promising results warrant a subsequent trial for DMD. This study was registered at ClinicalTrials.gov (NCT04129294).

The Effect of Genotype Differences on Cardiac Involvement in Cases Diagnosed with Duchenne Muscular Dystrophy

AIM

 Duchenne muscular dystrophy (DMD) is the most frequently seen muscular disease in childhood. Cardiac involvement is extremely important in terms of morbidity and mortality in these patients. Different studies have shown that mutations occurring in various exons are cardioprotective or increase cardiac involvement in DMD cases. The aim of this study was to examine the effect of genotype differences on cardiac involvement in patients diagnosed with DMD with genetic analysis.

MATERIAL AND METHOD

 A retrospective analysis of DMD patients followed up in the Muscle Diseases Centre of Health Sciences University Izmir Tepecik Training and Research Hospital was done.

RESULTS

 Evaluation was made of 120 male DMD patients with a mean age of 9.66 ± 5.10 years. According to the genetic analysis results, 76.7% deletions, 15.8% mutations, and 7.5% duplications were determined. Of the mutations determined, 65.8% were between exons 44 and 54, 17.5% between exons 1 and 18, and 9.2% between exons 19 and 43, 5.8% were non-sense mutations, and 1.7% were on exons >54. In the cases determined with cardiac involvement, the mean age of onset was 11.87 ± 3.11 years. When ejection fraction (EF) <56% or fractional shortening (FS) <28% was accepted as systolic dysfunction cardiac effect, 12.5% of the cases were determined with cardiac involvement. Of the cases determined with cardiac effects, 86.7% were aged >10 years. Electrocardiography was evaluated as normal in 54.5%, sinus tachycardia in 24.2%, short PR in 15.2%, and right and left ventricle hypertrophy in 8.1%. No statistically significant difference was determined in mutation types and location according to the age of cardiac involvement. The left ventricle (LV) posterior wall thickness value determined in the exon 44-54 group was higher than in DMD cases with other mutations. Although not statistically significant, an important result was that the LV posterior wall and IVSed values were evaluated to be high.

CONCLUSION

 The current study results and findings in literature have not found a clear relationship between genotypes and cardiac involvement in DMD cases.

Height development and multiple bone health indicators in children aged 2-12 years with Duchenne muscular dystrophy (DMD)

INTRODUCTION

Short stature is a frequent complication of DMD, and its pathomechanisms and influencing factors are specific to this disease and the idiosyncratic treatment for DMD.

PURPOSE

To establish the height growth curve of early DMD, and evaluate the potential influencing markers on height growth, provide further evidence for pathological mechanism, height growth management and bone health in DMD.

METHODS

A retrospective, cross-sectional study of 348 participants with DMD aged 2-12 years was conducted at West China Second Hospital of Sichuan University from January 2023 to October 2023.

RESULTS

The growth curve for 2-12 years old boys with DMD indicates a slower growth rate compared to the average population. At age two, children with DMD have a similar height to their peers, but gradually falls behind afterwards. Short stature was observed in children with DMD before and after GC exposure, and prolonged GC use exacerbated the retardation. BMI (β = -0.47, p = 0.007), BMD (β = -0.005, p = 0.014), β-CTX (β = 0.001, p = 0.002), delayed BA (β = 0.417, p < .001), GC duration (β = -0.006, p = 0.047) were independent influencing factors of height. Relevant bone health markers showed different sequential changing patterns.

CONCLUSION

The high proportion and progression of short stature are associated with the broad bone health status. Different bone indicators have different sensitivities and specificities and need to be considered together for clinical monitoring of bone health. This study provides evidence for the early monitoring of height development and relevant factors as part of bone health management in DMD, to minimize the occurrence of bone-related complications later in life.

Factors associated with lower forced vital capacity in children and adults with Duchenne muscular dystrophy using non-invasive ventilation: a multicenter analysis

BACKGROUND

Reduced forced vital capacity (FVC) is associated with morbidity and mortality in individuals with Duchenne muscular dystrophy (DMD). Non-invasive ventilation (NIV) is often prescribed for the treatment of sleep-disordered breathing (SDB), and chronic respiratory insufficiency. Despite the common practice of initiating NIV later in the progression of DMD, the factors influencing FVC subsequent to the commencement of NIV remain unclear.

OBJECTIVE

To evaluate the demographic, clinical and socioeconomic determinants of FVC% predicted across several cohorts of DMD children and adults prescribed NIV.

METHODS

A multicenter retrospective review of individuals with DMD prescribed NIV was performed between February 2016 to October 2020. Patients were identified from three sites: The Hospital for Sick Children, Canada; Rady Children's Hospital San Diego, USA; and University of California San Diego Health, USA. Multivariate regression analysis was performed to determine factors that influence FVC.

RESULTS

Fifty-nine male patients with DMD prescribed NIV (mean ± SD for age and BMI was 20.1 ± 6.7 years and 23.8 ± 8.8 kg/m2) were included. Following multivariate analysis, a lower FVC% predicted was associated with older age (β = -1.44, p = 0.001), presence of scoliosis (β = -16.94, p = 0.002), absent deflazacort prescription (β = 14.43, p = 0.009), and use of in-ex sufflator (β = -39.73, p < 0.001), respectively.

CONCLUSION

In our study, several factors were associated with reduced FVC% predicted in a DMD population using NIV. Future, prospective, longitudinal studies are imperative to comprehend the trajectory of FVC% predicted over time in individuals with DMD using NIV.

Histone deacetylase inhibition with givinostat: a multi-targeted mode of action with the potential to halt the pathological cascade of Duchenne muscular dystrophy

Muscle repair and regeneration are complex processes. In Duchenne muscular dystrophy (DMD), these processes are disrupted by the loss of functional dystrophin, a key part of the transmembrane dystrophin-associated glycoprotein complex that stabilizes myofibers, indirectly leading to progressive muscle wasting, subsequent loss of ambulation, respiratory and cardiac insufficiency, and premature death. As part of the DMD pathology, histone deacetylase (HDAC) activity is constitutively increased, leading to epigenetic changes and inhibition of muscle regeneration factors, chronic inflammation, fibrosis, and adipogenesis. HDAC inhibition has consequently been investigated as a therapeutic approach for muscular dystrophies that, significantly, works independently from specific genetic mutations, making it potentially suitable for all patients with DMD. This review discusses how HDAC inhibition addresses DMD pathophysiology in a multi-targeted mode of action and summarizes the recent evidence on the rationale for HDAC inhibition with givinostat, which is now approved by the United States Food and Drug Administration for the treatment of DMD in patients aged 6 years and older.

Transition of patients with Duchenne muscular dystrophy from paediatric to adult care: An international Delphi consensus study

BACKGROUND

Duchenne muscular dystrophy (DMD) is a rare neuromuscular disorder characterized by a progressive decline in muscle function, leading to loss of ambulation, respiratory and cardiac failure, and ultimately death. Improvements in DMD management have increased patient life expectancy; therefore, there is a growing requirement for patients to transfer from paediatric to adult care services. There is also a need for clear recommendations to guide this process.

AIM

To establish international consensus guidelines regarding best practices for transitioning patients with DMD from paediatric to adult care and ensuring continuity of treatment.

METHODS

Consensus statements were developed using the Delphi process and scored using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system. The initiative was led by a steering committee (one non-voting chair and two voting members) who recruited 15 expert panellists to form the consensus group. Following an initial systematic literature search, the consensus group voted in three voting rounds. Round 1 (free-text responses to questions) and Round 2 (importance ranking of statements) were completed using an online survey. Round 3 (voting on final consensus statements) took place during a virtual consensus meeting.

CONSENSUS STATEMENTS

Consensus was reached on 48 statements covering the topics of transition planning, the transition process, post-transfer management, communicating with young people with DMD and supporting them with the transition to adult life.

CONCLUSION

These consensus statements provide guidelines for improving transition practices for young people with DMD and promoting continued care at a comparable standard in adulthood.

Comprehensive multidisciplinary care for adult Duchenne muscular dystrophy in South Korea

BACKGROUND

With advancements in cardiorespiratory care, the lifespan of patients with Duchenne Muscular Dystrophy (DMD) has significantly increased, shifting the focus from merely extending life to enhancing quality of life and managing complications effectively. However, there is a lack of interest in the management of adult DMD, highlighting a gap in holistic care approaches for this aging population.

OBJECTIVE

This study aims to assess the current state of care for adult DMD patients in South Korea, focusing on multidisciplinary management and identifying key areas for improvement.

METHODS

We retrospectively reviewed the medical records of 168 adult DMD patients who visited the Pulmonary Rehabilitation Center at [blinded for review] from 2022 to 2023. Demographic data, ventilatory support status, cardiac function, gastrointestinal, renal, and skeletal health were analyzed.

RESULTS

Of the patients, 93.8% required non-invasive ventilatory support, while 6.2% used invasive ventilation. Cardiac medications were prescribed to 82.1% of patients, with beta-blockers being the most common. Renal dysfunction was found in 10.1% of patients, with one patient requiring dialysis. A significant portion (54.8%) were on anti-constipation medications due to gastrointestinal issues, and 41.7% of patients had undergone scoliosis correction surgery. Bone mineral density was significantly reduced in most patients, with an average Z-score of -3.3.

CONCLUSIONS

This study emphasizes the need for improved care protocols that enhance lifespan and quality of life and manage complications for patients with DMD. This study advocates a shift in healthcare strategies toward a more integrated and holistic care model for adult patients with DMD.

Brain glucose metabolism as a neuronal substrate of the abnormal behavioral response to stress in the mdx mouse, a model of Duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD) is associated with a range of cognitive and behavioral problems. Brain-related comorbidities show clinical heterogeneity depending on the position of the mutation within the multi-promoter dystrophin (DMD) gene, likely due to the differential impact of mutations on the expression of distinct brain dystrophins. A deficiency of the full-length brain dystrophin, Dp427, has been associated with enhanced stress reactivity, characterized by abnormal fear responses in both patients and mdx mouse model. However, the neural substrates of this phenotype are still unknown. Here, we undertook the first functional imaging study of the mdx mouse brain, following expression of the typical unconditioned fear response expressed by mdx mice after a short scruff restraint and one week later after recovery from stress. We compared the brain glucose metabolism in 12 brain structures of mdx and WT littermate male mice using [18F]FDG PET imaging. Restraint-stress induced a global decrease in [18F]FDG uptake in mdx mice, while no difference was found between genotypes when mice were tested one week later under non-stressful conditions. A subset of brain structures were particularly affected by stress in mdx mice, and we identified abnormal correlations between fear responses and metabolism in specific structures, and altered co-activation of the hypothalamus with several subcortical structures. Our data support the hypothesis that enhanced stress reactivity due to loss of brain Dp427 relies on abnormal activation of the brain fear circuit and deregulation of a hypothalamus-dependent pathway.

Triumphs, Trials, and Future Considerations in Genetic Therapies for Hereditary Neuromuscular Diseases

Neuromuscular diseases include conditions that affect the spinal motor neurons, peripheral nerves, neuromuscular junctions, and muscles, and they can result from acquired and inherited causes. The number of genetic therapies targeting the inherited causes of neuromuscular diseases has surged in the last decade. This review aims to highlight the current state of genetic therapies within the framework of precision medicine, focusing on the achievements and the gaps that remain. A major emphasis is on spinal muscular atrophy, Duchenne muscular dystrophy, and amyotrophic lateral sclerosis, as these neuromuscular diseases have seen tremendous recent advancements. We will also discuss the future considerations necessary to accelerate the development of next-generation genetic therapies and enhance therapeutic outcomes for patients with neuromuscular diseases.

Optimizing DMD management in Asia: Current challenges and future directions

BACKGROUND

Since 1970, advances in Duchenne muscular dystrophy (DMD) management have significantly extended the patients' life expectancy. However, DMD remains universally fatal.

OBJECTIVE

To understand the current DMD management standards and practices in Asia and to evaluate inconsistencies, unmet needs, and future directions for DMD patient management in the region.

METHODS

Clinical experts from Hong Kong, Singapore, and Taiwan convened in September 2023 to discuss DMD diagnosis, assessment, treatment, and management best practices. A pre-meeting survey was also administered to explore professional perspectives and practices and refine the discussion focus.

RESULTS

Genetic profiling has become the pivotal diagnostic tool and has been universally adopted by experts. Steroid therapy is recognized as the cornerstone of DMD care. However, there are various opinions regarding the timing of its initiation and whether it should be continued after the loss of ambulation. Gene therapy has the potential to significantly improve outcomes in patients with DMD. However, its adoption is hampered by high costs, the potential for serious adverse events, and difficulties with patient selection. Governments and manufacturers must work together to improve its affordability. Establishing a centralized DMD registry garnered strong support from the experts as it promised to provide insights into unique DMD subtypes, standardize treatment protocols, and facilitate the conduct of clinical trials. Furthermore, the introduction of gene therapy has highlighted the need for generating long-term safety and effectiveness data in patients with DMD. Lastly, a centralized patient registry can be used to inform policy decisions.

CONCLUSIONS

DMD care in Asia is characterized by substantial heterogeneity, with financial and reimbursement issues playing a major role in management decisions. A centralized patient registry has the potential to address these concerns by providing a valuable source of information.

Lessons learned from the RE(ACT) conference on medical devices for rare diseases

The field of rare disease therapeutics has witnessed significant growth in recent years, highlighting the need for diverse therapeutic approaches to cater to the unique needs of individuals with rare diseases. Rare disease therapies encompass a broad spectrum of interventions, including orphan medicinal products, orphan medical devices, rehabilitative therapies, and digital therapeutics, with the lines between these categories blurring. This paper covers the session of the RE (ACT)-IRDiRC Conference 2023 and delves into the landscape of orphan medical device research and development, shedding light on the challenges and opportunities in this burgeoning field. It provides a short overview of the different international legislations in the field. In addition, it highlights several exemplary orphan medical devices. The first example is an exoskeleton for boys with Duchenne Muscular Dystrophy, enabling them to maintain arm functionality and independence. Another example presented was an EEG device linked to an app detecting seizures in rare epilepsy conditions, which alerts caregivers to seizures in real-time but also facilitates objective seizure reporting for clinicians, aiding in diagnosis and treatment optimization. It also showcases the role of gamification and enabling technologies in addressing rare diseases, by showing a game designed for children with cystic fibrosis, and a telemedicine system for rehabilitation therapy. Both solutions aim to improve patients' understanding of their conditions and enhance their self-management. In conclusion, this paper underscores the critical need for patient-centric orphan and pediatric medical devices to provide therapeutic options for individuals with rare diseases. It highlights the impact of existing devices on enhancing the quality of life for rare disease patients and emphasizes the necessity for greater incentives and support for research and development in this field.

Long-Term Survival and Myocardial Function Following Systemic Delivery of Delandistrogene Moxeparvovec in DMDMDX Rats

Delandistrogene moxeparvovec is a gene transfer therapy for Duchenne muscular dystrophy (DMD) that uses an adeno-associated viral vector to deliver a micro-dystrophin transgene to skeletal and cardiac muscle. This study evaluated the long-term survival and cardiac efficacy of delandistrogene moxeparvovec in a DMD-mutated (DMDMDX) rat model of DMD-related cardiomyopathy. DMDMDX male rats, aged 21-42 days, were injected with 1.33 × 1014 viral genomes/kilogram (vg/kg) delandistrogene moxeparvovec and followed for 12, 24, and 52 weeks. Ambulation was recorded via the Photobeam Activity System, whereas echocardiograms, cardiomyocyte contractility, calcium handling, and histological analysis of fibrosis were used to evaluate cardiac disease at 12-, 24-, and 52-weeks post-treatment. A separate cohort of rats was used to assess the impact of delandistrogene moxeparvovec on survival. Treatment with delandistrogene moxeparvovec extended median survival in DMDMDX rats to >25 months versus the 13-month median survival in saline-control-treated DMDMDX rats. Compared with saline control, delandistrogene moxeparvovec therapy elicited statistically significant improvements across cardiac parameters approaching wild-type values with additional benefits in mobility, histopathology, and fibrosis observed. Transgene expression was maintained up to >25 months and micro-dystrophin expression was broadly distributed across skeletal and cardiac muscle. Taken together, these findings demonstrate long-term cardiac efficacy and improved survival following delandistrogene moxeparvovec treatment in DMDMDX rats.

Safety and effectiveness of ataluren in patients with Duchenne muscular dystrophy: single-center experience from Saudi Arabia

OBJECTIVE

Duchenne muscular dystrophy (DMD) is a rare X-linked neurodegenerative disorder caused by mutations in the DMD gene. This study examined the efficacy and safety of ataluren, the first oral treatment for DMD with nonsense mutations (nmDMD), in patients in the Middle East.

METHODS

This retrospective longitudinal study assessed the outcomes of seven boys with nmDMD who received treatment with ataluren and follow-up at a single center since 2016.

RESULTS

The median patient age at treatment initiation was 8.04 years (range: 3.3-9.92), and the median duration of exposure was 3.95 years (interquartile range = 4.42 years). Five patients were still ambulatory at the last follow-up. Ataluren was more effective in individuals with baseline 6-min walking distance (6MWD) ≥300 m, as these patients had smaller declines in 6MWD and North Star Ambulatory Assessment scores. Pulmonary function was well preserved in all patients, with no patients having forced vital capacity <60% at their last follow-up. Six patients maintained normal cardiac function, whereas one patient developed heart failure before starting ataluren treatment.

CONCLUSIONS

Our results demonstrated both the efficacy and safety of ataluren. Early initiation of ataluren treatment delayed the loss of ambulation and cardiorespiratory milestones.

Research hotspots and trends for Duchenne muscular dystrophy: a machine learning bibliometric analysis from 2004 to 2023

Aims

The aim of this study was to conduct a bibliometric analysis of the relevant literature on Duchenne muscular dystrophy (DMD) to ascertain its current status, identify key areas of research and demonstrate the evolution of the field.

Methods

The analysis sourced documents from the Science Citation Index Expanded in the Web of Science core collection, utilizing CiteSpace software and an online bibliometric platform to analyze collaborative networks among authors, institutions and countries, and to map out the research landscape through journal and reference evaluations. Keyword analyses, including clustering and emergent term identification, were conducted, alongside the development of knowledge maps.

Results

The study included 9,277 documents, indicating a rising publication trend in the field. The Institut National de la Santé et de la Recherche Médicale emerged as the top publishing institution, with Francesco Muntoni as the most prolific author. The United States dominated in publication output, showcasing significant leadership. The keyword analysis highlighted 786 key emergent terms, primarily focusing on the mechanisms, diagnostics and treatment approaches in DMD.

Conclusion

The field of DMD research is experiencing robust growth, drawing keen interest globally. A thorough analysis of current research and trends is essential for advancing knowledge and therapeutic strategies in this domain.

A computational tool to optimize clinical trial parameter selection in Duchenne muscular dystrophy: A practical guide and case studies

Duchenne muscular dystrophy (DMD), a rare pediatric disease, presents numerous challenges when designing clinical trials, mainly due to the scarcity of available trial participants and the heterogeneity of disease progression. A quantitative clinical trial simulator (CTS) has been developed based on previously published five disease progression models describing each of the longitudinal changes in the velocity at which individuals can complete specified timed functional tests, frequently used as clinical trial efficacy endpoints (supine-stand, 4-stair climb, and 10 m walk/run test or 30-foot walk/run test), as well as each of the longitudinal changes in forced vital capacity and North Star Ambulatory Assessment total score. The model-based CTS allows researchers to optimize the selection of numerous trial parameters for designing trials for the five functional measures commonly used as endpoints in DMD clinical trials. This case report serves as a demonstration of the tool's functionality while providing an easy-to-follow guide for users to reference when preparing simulations of their own design. Two case studies, using input selection based on previous DMD clinical trials, provide realistic examples of how the tool can help optimize clinical trial design without the risk of decreasing statistical significance. This optimization allows researchers to mitigate the risk of designing trials that may be longer, larger, or more inclusive/exclusive than necessary.

An Updated Analysis of Exon-Skipping Applicability for Duchenne Muscular Dystrophy Using the UMD-DMD Database

BACKGROUND/OBJECTIVES

Antisense oligonucleotide (ASO)-mediated exon-skipping is an effective approach to restore the disrupted reading frame of the dystrophin gene for the treatment of Duchenne muscular dystrophy (DMD). Currently, four FDA-approved ASOs can target three different exons, but these therapies are mutation-specific and only benefit a subset of patients. Understanding the broad applicability of exon-skipping approaches is essential for prioritizing the development of additional therapies with the greatest potential impact on the DMD population. This review offers an updated analysis of all theoretical exon-skipping strategies and their applicability across the patient population, with a specific focus on DMD-associated mutations documented in the UMD-DMD database. Unlike previous studies, this approach leverages the inclusion of phenotypic data for each mutation, providing a more comprehensive and clinically relevant perspective.

METHODS

The theoretical applicability of all single and double exon-skipping strategies, along with multi exon-skipping strategies targeting exons 3-9 and 45-55, was evaluated for all DMD mutations reported in the UMD-DMD database.

RESULTS

Single and double exon-skipping approaches were applicable for 92.8% of large deletions, 93.7% of small lesions, 72.4% of duplications, and 90.3% of all mutations analyzed. Exon 51 was the most relevant target and was applicable for 10.6% of all mutations and 17.2% of large deletions. Additionally, two multi-exon-skipping approaches, targeting exons 45-55 and 3-9, were relevant for 70.6% of large deletions and 19.2% of small lesions.

CONCLUSIONS

Current FDA-approved ASOs were applicable to 27% of the UMD-DMD population analyzed, leaving a significant portion of patients without access to exon-skipping therapies. The clinical translation of alternative approaches is critical to expanding the accessibility of these therapies for the DMD population.

Neurocognitive functioning among children and young people with Duchenne Muscular Dystrophy: A systematic review and meta-analysis

Objective: The neurocognitive aspects of DMD have received less attention than the physiological sequalae. This study conducted a systematic review and meta-analysis of available literature on the neurocognitive profile of children and young people with DMD. Method: Five databases (EMBASE, Medline, PsycInfo, Scopus and Web of Science) and the grey literature was searched on 27th January 2023. Eligible articles were available in English and reported neurocognitive outcomes. Neurocognitive domains reported in a comparable way across a minimum of three studies were included. The neurocognitive domains of Full-Scale IQ (FSIQ), Verbal IQ (VIQ), Performance IQ (PIQ) and Working memory (WMI) derived from Wechsler scales and receptive vocabulary ability derived from the Peabody Picture Verbal Test (PPVT) were included. A single mean meta-analysis was completed. Results: Relevant data was extracted and presented for 38 eligible studies; 2 of which are from grey literature. Results suggest children with DMD perform around 1SD below non-clinical norms for FSIQ, PIQ, VIQ and WMI. Unlike VIQ, scores derived from the PPVT were within the non-clinical norms. Studies were of moderate - high quality, there was significant heterogeneity and no publication bias. Conclusion: A systematic review of working memory has not previously been completed, it appears that children with DMD perform around 1SD below the mean, like FSIQ, PIQVIQ and WMI. The PPVT is a measure of receptive verbal ability and caution is recommended around the interchangeability of PPVT scores and the wider construct of verbal intelligence.

Clinical Evidence Supporting FDA Approval of Gene and RNA Therapies for Rare Inherited Conditions

BACKGROUND

Gene and RNA therapies have potential to transform the treatment of rare inherited diseases, but there are concerns about the evidence supporting their use and high costs.

OBJECTIVE

We analyze the evidence supporting Food and Drug Administration (FDA) approval of gene and RNA therapies for rare inherited diseases and discuss implications for clinical practice and policy.

METHODS

We conducted a qualitative analysis of FDA documents outlining the basis of approval for gene and RNA therapies approved for rare inherited diseases between 2016 and 2023. For each drug, we gathered five characteristics of the evidence supporting FDA approval (no phase 3 trial, nonrandomized, no clinical endpoint, lack of demonstrated benefit, and significant protocol deviation) and four characteristics of the FDA approval process (prior rejection or complete response, negative committee vote, discrepancy between label and trial population, and boxed warning). The main outcome was the number of drugs with each characteristic.

RESULTS

Between 2016 and 2023, 19 gene and RNA therapies received FDA approval to treat rare inherited diseases. The most common limitations in the evidence supporting approval of these drugs were nonrandomized studies (8/19, 42%), no clinical endpoint (7/19, 37%), lack of demonstrated benefit or inconsistent results (4/19, 21%), and no phase 3 trial (4/19, 21%). Half (3/6) of accelerated approvals and 57% (5/9) of drugs with breakthrough designation had nonrandomized trials, and gene therapies with one-time dosing were overrepresented (5/7, 71%) among the drugs with nonrandomized trials. Five of six accelerated approvals (83%) and five of nine pediatric drugs (56%), most of which were indicated for Duchenne muscular dystrophy, had no clinical endpoint. Four of nine (44%) pediatric drugs and four of six (67%) accelerated approvals failed to demonstrate benefit compared with none of the nonpediatric drugs and none of the traditional approvals. Five drugs, which all had different indications and represented a mix of RNA and gene therapies, did not have any of these evidence characteristics. Among drugs that received prior rejections or negative committee opinions, all four had nonrandomized trials and lacked a clinical endpoint, and 75% (3/4) lacked demonstrated benefit. Five of nine (56%) pediatric drugs were indicated for broader age groups according to the drug label compared with the trial populations. Of the three drugs with boxed warnings, two had pediatric indications and nonrandomized studies, and one had no phase 3 trial.

CONCLUSIONS

Issues related to trial design, outcome, and data integrity in the evidence supporting FDA approval of rare inherited disease gene and RNA therapies raise questions about whether this evidence is adequate to inform prescribing decisions. Gene and RNA therapies with accelerated approval and pediatric indications were overrepresented among drugs lacking clinical endpoints or demonstrated benefit and should be the focus of efforts to reduce uncertainty in the evidence.

Characterization of patients with Duchenne muscular dystrophy across previously developed health states

Project HERCULES has developed a natural history model (NHM) of disease progression in Duchenne muscular dystrophy (DMD) that comprises eight ordered health states (two ambulatory states, one transfer state indicating increased caregiver burden in which patients cannot walk/run 10m or rise from floor but can still support their own weight, and five non-ambulatory states). The current study used data from nine sources (clinical trial placebo arms, one real-world dataset, and three natural history datasets) to further characterize patients with DMD according to these health states. The study included 1,173 patients across 5,306‬ visits. Patients were on average older and exhibited worse ambulatory, pulmonary, upper limb, and cardiac functions with each successive health state. Mean±SE ages increased monotonically across health states, starting with 8.47±0.07 for early ambulatory, 10.86±0.13 for late ambulatory, 11.65±0.35 for transfer state, and ranging from 13.17±0.32 to 16.84±0.37 for the non-ambulatory states. North Star Ambulatory Assessment (NSAA) total score, which measures motor function and ranges from 34 (best) to 0 (worst), was 23.7 (interquartile range [IQR]: 20-30) for early ambulatory patients, 12.7 (IQR: 9-16) for late ambulatory patients, and 3.9 (IQR: 2-5) for transfer patients. Pulmonary function as measured by mean±SE of forced vital capacity percent predicted (FVC%p) was 94.5±0.8 for early ambulatory, 89.1±1.4 for late ambulatory, and 80.2±2.8 for transfer states, and decreased from 77.2±1.7 to 20.6±1.6 across the five non-ambulatory health states. In summary, these findings further characterize health states and their interpretation in economic modeling and decision-making in DMD management.

Fostering tissue engineering and regenerative medicine to treat musculoskeletal disorders in bone and muscle

The musculoskeletal system, which is vital for movement, support, and protection, can be impaired by disorders such as osteoporosis, osteoarthritis, and muscular dystrophy. This review focuses on the advances in tissue engineering and regenerative medicine, specifically aimed at alleviating these disorders. It explores the roles of cell therapy, particularly Mesenchymal Stem Cells (MSCs) and Adipose-Derived Stem Cells (ADSCs), biomaterials, and biomolecules/external stimulations in fostering bone and muscle regeneration. The current research underscores the potential of MSCs and ADSCs despite the persistent challenges of cell scarcity, inconsistent outcomes, and safety concerns. Moreover, integrating exogenous materials such as scaffolds and external stimuli like electrical stimulation and growth factors shows promise in enhancing musculoskeletal regeneration. This review emphasizes the need for comprehensive studies and adopting innovative techniques together to refine and advance these multi-therapeutic strategies, ultimately benefiting patients with musculoskeletal disorders.

Utilization of Multi-Parametric Quantitative Magnetic Resonance Imaging in the Early Diagnosis of Duchenne Muscular Dystrophy

BACKGROUND

It is challenging to diagnose suspected Duchenne muscular dystrophy (DMD) patients in the very early stage of the disease. More evidence is needed to demonstrate the potential of quantitative MRI (qMRI) in precisely identifying patients before substantial physical decline occurs.

PURPOSE

To assess the early diagnostic performance of multi-parametric qMRI for DMD patients, and the ability to identify DMD patients with mild functional decline.

STUDY TYPE

Prospective.

SUBJECTS

One hundred and forty DMD subjects (9.0 ± 2.2 years old), 24 male healthy controls (HCs) (9.2 ± 2.5 years old).

FIELD STRENGTH/SEQUENCE

3.0 T/3-point Dixon, T1-mapping, and T2-mapping.

ASSESSMENT

qMRI measurements (fat fraction [FF], T1, and T2) of 11 thigh muscles (rectus femoris [RF], vastus lateralis [VL], vastus intermedius, vastus medialis, gracilis, sartorius, adductor longus, adductor magnus [AM], semitendinosus, semimembranosus, biceps femoris long head [BFLH]) on the right side were conducted. NorthStar ambulatory assessment (NSAA) score used to evaluate the function of DMD patients and divided them into three subgroups: mild (76-100 score), moderate (51-75 score), and severe (0-50 score) functional decline.

STATISTICAL TESTS

Independent t-test, ANOVA analysis, and receiver operating characteristic (ROC) curves. A P-value <0.05 was considered statistically significant.

RESULTS

Compared with HCs, FF and T2 were significantly higher in the group of all DMD patients, while T1 was significantly lower. The combination of T1 and T2 in RF, VL, AM, and BFLH achieved excellent area under curve (AUCs) (0.967-0.992) in differentiating five DMD patients without abnormal fat infiltration from HCs. Overall, T2 reached higher AUCs than FF and T1 in distinguishing DMD with mild functional decline from HCs, whereas FF achieved higher AUCs than T1 and T2 in distinguishing three DMD subgroups with functional decline.

DATA CONCLUSION

Multi-parametric qMRI demonstrate effective diagnostic capabilities for DMD patients in the early stage of the disease, and can identify patients with mild physical decline.

LEVEL OF EVIDENCE

2 TECHNICAL EFFICACY: Stage 3.

Cataloging health state utility estimates for Duchenne muscular dystrophy and related conditions

BACKGROUND

Duchenne muscular dystrophy (DMD) is a genetic disease resulting in progressive muscle weakness, loss of ambulation, and cardiorespiratory complications. Direct estimation of health-related quality of life for patients with DMD is challenging, highlighting the need for proxy measures. This study aims to catalog and compare existing published health state utility estimates for DMD and related conditions.

METHODS

Using two search strategies, relevant utilities were extracted from the Tufts Cost-Effectiveness Analysis Registry, including health states, utility estimates, and study and patient characteristics. Analysis One identified health states with comparable utility estimates to a set of published US patient population utility estimates for DMD. A minimal clinically important difference of ± 0.03 was applied to each DMD utility estimate to establish a range, and the registry was searched to identify other health states with associated utilities that fell within each range. Analysis Two used pre-defined search terms to identify health states clinically similar to DMD. Mapping was based on the degree of clinical similarity.

RESULTS

Analysis One identified 4,308 unique utilities across 2,322 cost-effectiveness publications. The health states captured a wide range of acute and chronic conditions; 34% of utility records were extrapolated for US populations (n = 1,451); 1% were related to pediatric populations (n = 61). Analysis Two identified 153 utilities with health states clinically similar to DMD. The median utility estimates varied among identified health states. Health states similar to the early non-ambulatory DMD phase exhibited the greatest difference between the median estimate of the sample (0.39) and the existing estimate from published literature (0.21).

CONCLUSIONS

When available estimates are limited, using novel search strategies to identify utilities of clinically similar conditions could be an approach for overcoming the information gap. However, it requires careful evaluation of the utility instruments, tariffs, and raters (proxy or self).

Gene therapy for Duchenne Muscular Dystrophy: assessing the readiness of Italian centres of expertise

Objectives

Duchenne muscular dystrophy (DMD) is a heritable disorder that causes a rapid and progressive loss of ambulatory skills. There is no curative therapy for this pathology, that is currently managed with a combination of physiotherapy and pharmacological interventions limiting the progression of the disease (e.g. corticosteroids, cardiac medications). However, a new opportunity is represented by gene therapy, a promising treatment that, however, requires significant expertise during the whole delivery of care and a solid organisational infrastructure. An organisational strategy that could effectively support its delivery to DMD patients in Italy is the hub-and-spoke model. However, an accurate portrait of the present network of DMD centres of expertise in Italy and of their readiness in the delivery of gene therapy is paramount, to facilitate access to this experimental medicine in the future.

Methods

In this context, the present study aimed to map the DMD centres of expertise in Italy and later evaluate their preparedness in terms of gene therapy delivery. For this purpose, a series of items was proposed to 30 centres in Italy, of which 20 responded.

Results

After assessing the readiness of the involved centres in terms of patient preparation, therapy infusion, close surveillance, and long-term follow-up, we proposed a suitable organizational model, namely a flexible hub-and-spoke model, for the delivery of gene therapy in the Italian DMD network and solutions to tackle the challenges emerged from the survey.

Conclusion

Overall, the present study detected an adequate readiness of the Italian DMD centres of expertise, despite observing a significant room for improvement in digital infrastructures, culture, and training.

Subspecialty Health Care Utilization in Pediatric Patients With Muscular Dystrophy in the United States

Background and Objectives

Standards of care exist to optimize outcomes in Duchenne and Becker muscular dystrophy (DBMD), caused by alterations in the DMD gene; however, there are limited data regarding health care access in these patients. This study aims to characterize outpatient subspecialty care utilization in pediatric patients with DBMD.

Methods

This retrospective cohort study used administrative claims data from IBM MarketScan Medicaid and Commercial Claims and Encounters Research Databases (2013-2018). Male patients 1-18 years with an ICD-9/10 diagnosis code for hereditary progressive muscular dystrophy between January 1, 2013, and December 31, 2017, were included. Participants were stratified into 3 age cohorts: 1-6 years, 7-12 years, and 13-18 years. The primary outcome was rate of annual neurology visits. Secondary outcomes included annual follow-up rates in other subspecialties and proportion of days covered (PDC) by corticosteroids.

Results

A total of 1,386 patients met inclusion-347 (25.0%) age 1-6 years, 502 (36.2%) age 7-12 years, and 537 (38.7%) age 13-18 years. Heart failure, respiratory failure, and technology dependence increased with age (p for all<0.05). The rate of neurology visits per person-year was 0.36 and did not differ by age. Corticosteroid use was low; 30% of person-years (1452/4829) had a PDC ≥20%. Medicaid insurance was independently associated with a lower likelihood of annual neurology follow-up (OR 0.23; 95% CI 0.18-0.28).

Discussion

The rate of annual neurology follow-up and corticosteroid use in patients with DBMD is low. Medicaid insurance status was independently associated with a decreased likelihood of neurology follow-up, while age was not, suggesting that factors other than disease severity influence neurology care access. Identifying barriers to regular follow-up is critical in improving outcomes for patients with DBMD.

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.

Eteplirsen Treatment for Duchenne Muscular Dystrophy: A Qualitative Patient Experience Study

INTRODUCTION

Duchenne muscular dystrophy (DMD) is characterized by rapid functional decline. Current available treatment options aim to delay disease progression or stabilize physical function. To aid in healthcare providers' understanding of the symptoms of disease that impact patients' experience, this study explored children's physical functioning, activities of daily living (ADLs), and health-related quality of life (HRQoL) after receiving eteplirsen, a weekly infusion indicated for individuals with DMD with exon 51 skip-amenable mutations.

METHODS

Fifteen caregivers of male individuals with DMD participated in a 60-min, semi-structured interview. Open-ended questioning explored changes in the children's condition or maintenance in abilities since eteplirsen initiation.

RESULTS

Children with DMD (age 7-15 years [mean 10.9]; steroid treatment at interview, n = 8; time since eteplirsen initiation 3-24 months [mean 14.9]) were described by caregivers as ambulatory (n = 9) and non-ambulatory (n = 6). Caregivers of ambulatory children reported improvements or maintenance of walking ability (n = 7/9), running (n = 6/9), and using stairs (n = 4/9). Continued decline in using stairs was reported by two caregivers. In upper-limb functioning, improvements or maintenances in fine-motor movements were reported by nearly half of all caregivers (n = 7/15), with one caregiver noting a continued decline. Subsequent improvements or maintenances in ADLs were described. Improvements or maintenances in fatigue (n = 9/15), muscle weakness (n = 7/15), and pain (n = 6/15) were reported, although some caregivers described a continued decline (n = 3/15 fatigue, n = 1/15 muscle weakness, n = 2/15 pain). Importantly, most caregivers who reported maintenances in ability perceived this as a positive outcome (n = 6/9).

CONCLUSION

This exploratory study indicated that most caregivers perceived improvements or maintenances in aspects of their child's physical functioning, ADLs, and HRQoL since eteplirsen initiation, which they perceived to be a positive outcome.

Duchenne muscular dystrophy in Saudi Arabia: a review of the current literature

In the past three decades, significant improvements have occurred in the study of Duchenne muscular dystrophy (DMD). DMD is a rare, severe neuromuscular disease that causes death due to cardiovascular and respiratory complications among affected boys. Since the 1980s, ongoing preclinical and clinical studies have been conducted to explore the disease in depth and discover potential therapeutic strategies. In Saudi Arabia, it is unclear whether health services and research efforts are keeping pace with global achievements. Therefore, this review aims to explore the diagnostic and management strategies and research efforts in Saudi Arabia over the past three decades. I searched the PubMed/Medline, Scopus, and Web of Science databases and included all published articles on the epidemiology, genetics, diagnosis, and management of DMD/BMD in this review. The findings suggest a lack of local standardized diagnostic strategies, a poor understanding of epidemiology and common pathogenic variants, and a critical need for preclinical and clinical research. At the time of writing, no such comprehensive review has been published. Challenges, limitations, and future perspectives are also discussed in this article.

Exploring lipin1 as a promising therapeutic target for the treatment of Duchenne muscular dystrophy

BACKGROUND

Duchenne muscular dystrophy (DMD) is a progressive and devastating muscle disease, resulting from the absence of dystrophin. This leads to cell membrane instability, susceptibility to contraction-induced muscle damage, subsequent muscle degeneration, and eventually disability and early death of patients. Currently, there is no cure for DMD. Our recent studies identified that lipin1 plays a critical role in maintaining myofiber stability and integrity. However, lipin1 gene expression levels are dramatically reduced in the skeletal muscles of DMD patients and mdx mice.

METHODS

To identify whether increased lipin1 expression could prevent dystrophic pathology, we employed unique muscle-specific mdx:lipin1 transgenic (mdx:lipin1Tg/0) mice in which lipin1 was restored in the dystrophic muscle of mdx mice, intramuscular gene delivery, as well as cell culture system.

RESULTS

We found that increased lipin1 expression suppressed muscle degeneration and inflammation, reduced fibrosis, strengthened membrane integrity, and resulted in improved muscle contractile and lengthening force, and muscle performance in mdx:lipin1Tg/0 compared to mdx mice. To confirm the role of lipin1 in dystrophic muscle, we then administered AAV1-lipin1 via intramuscular injection in mdx mice. Consistently, lipin1 restoration inhibited myofiber necroptosis and lessened muscle degeneration. Using a cell culture system, we further found that differentiated primary mdx myoblasts had elevated expression levels of necroptotic markers and medium creatine kinase (CK), which could be a result of sarcolemmal damage. Most importantly, increased lipin1 expression levels in differentiated myoblasts from mdx:lipin1Tg/0 mice substantially inhibited the elevation of necroptotic markers and medium CK levels.

CONCLUSIONS

Overall, our data suggest that lipin1 is a promising therapeutic target for the treatment of dystrophic muscles.

Cardiomyopathy in Duchenne Muscular Dystrophy and the Potential for Mitochondrial Therapeutics to Improve Treatment Response

Duchenne muscular dystrophy (DMD) is a progressive neuromuscular disease caused by mutations to the dystrophin gene, resulting in deficiency of dystrophin protein, loss of myofiber integrity in skeletal and cardiac muscle, and eventual cell death and replacement with fibrotic tissue. Pathologic cardiac manifestations occur in nearly every DMD patient, with the development of cardiomyopathy-the leading cause of death-inevitable by adulthood. As early cardiac abnormalities are difficult to detect, timely diagnosis and appropriate treatment modalities remain a challenge. There is no cure for DMD; treatment is aimed at delaying disease progression and alleviating symptoms. A comprehensive understanding of the pathophysiological mechanisms is crucial to the development of targeted treatments. While established hypotheses of underlying mechanisms include sarcolemmal weakening, upregulation of pro-inflammatory cytokines, and perturbed ion homeostasis, mitochondrial dysfunction is thought to be a potential key contributor. Several experimental compounds targeting the skeletal muscle pathology of DMD are in development, but the effects of such agents on cardiac function remain unclear. The synergistic integration of small molecule- and gene-target-based drugs with metabolic-, immune-, or ion balance-enhancing compounds into a combinatorial therapy offers potential for treating dystrophin deficiency-induced cardiomyopathy, making it crucial to understand the underlying mechanisms driving the disorder.

Intervention with hand orthosis: experience from boys with Duchenne muscular dystrophy and their parents

PURPOSE

To identify and describe possible ways of experiencing an intervention with hand orthoses in a study group including boys with Duchenne muscular dystrophy (DMD) and their parents. To capture the experiences of the persons directly involved as well as their family members.

MATERIAL AND METHODS

Eight boys with DMD (aged 8-21; median age 17.7) and five of their parents were interviewed immediately post-intervention. Additionally, follow-up interviews were later performed with five boys and three parents.

RESULTS

Ten categories of intervention experiences emerged and were allocated to three aspects: "Prerequisites in the treatment situation", "The intervention makes a difference" and "Instilling hope for the future". The requirements for intervention success include co-operation with parents and hand orthoses with a good fit. Maintained or increased joint mobility, reduced pain and improved occupational performance were experienced.

CONCLUSION

The boys and parents perceived that the intervention with hand orthoses could counteract the deterioration of the boys' hands. This instilled hope of preserving occupational performance throughout life. They also considered that a good hand-orthosis fit, appropriate adjustments to daily routines and good co-operation with the people around them were important for the intervention to be and remain successful.

Current Concepts in the Orthopaedic Management of Duchenne Muscular Dystrophy

Duchenne muscular dystrophy (DMD), a genetic condition marked by progressive muscle degeneration, presents notable orthopaedic challenges, especially scoliosis, which deteriorates patients' quality of life by affecting sitting balance and complicating cardiac and respiratory functions. Current orthopaedic management strategies emphasize early intervention with corticosteroids to delay disease progression and the use of surgical spinal fusion to address severe scoliosis, aiming to enhance sitting balance, alleviate discomfort, and potentially extend patient lifespan. Despite advancements, optimal management requires ongoing research to refine therapeutic approaches, ensuring improved outcomes for patients with DMD. This review synthesizes recent findings on surgical and nonsurgical interventions, underscoring the importance of a multidisciplinary approach tailored to the dynamic needs of patients with DMD.

Discovery of Quinazoline and Quinoline-Based Small Molecules as Utrophin Upregulators via AhR Antagonism for the Treatment of Duchenne Muscular Dystrophy

Duchenne muscular dystrophy (DMD) is a fatal muscle-wasting disease caused by the absence of a dystrophin protein. Elevating utrophin, a dystrophin paralogue, offers an alternative therapeutic strategy for treating DMD, irrespective of the mutation type. Herein, we report the design and synthesis of novel quinazoline and quinoline-based small molecules as potent utrophin modulators screened via high throughput In-Cell ELISA in C2C12 cells. Remarkably, lead molecule SG-02, identified from a library of 70 molecules, upregulates utrophin 2.7-fold at 800 nM in a dose-dependent manner, marking the highest upregulation within the nanomolar range. SG-02's efficacy was further validated through DMD patient-derived cells, demonstrating a significant 2.3-fold utrophin expression. Mechanistically, SG-02 functions as an AhR antagonist, with excellent binding affinity (Kd = 41.68 nM). SG-02 also enhances myogenesis, as indicated by an increased MyHC expression. ADME evaluation supports SG-02's oral bioavailability. Overall, SG-02 holds promise for addressing the global DMD population.

Functional trajectories before and after loss of ambulation in Duchenne muscular dystrophy and implications for clinical trials

This study examined functional trajectories of subjects during the transition phase between ambulatory and non-ambulatory Duchenne muscular dystrophy (DMD) to inform clinical trial designs for new therapeutics. Ambulatory, pulmonary, and upper limb function leading up to loss of ambulation (LoA) and non-ambulatory measures following LoA were quantified; time ordering of pulmonary and upper limb milestones relative to LoA were determined; and the 10-second time threshold for 10-meter walk/run (10MWR) as a marker of approaching LOA was explored. Included in this analysis were 51 subjects aged between 7 and 18 years who experienced LoA during follow-up in the PRO-DMD-01 natural history study. Mean age at LoA was 12.7 (7.1-18.6) years. Mean annual rates of decline in forced vital capacity (FVC) <80%-predicted and performance of upper limb (PUL) 1.2 total score were smaller before than after LoA, but not significantly (FVC %-predicted: 5.6% vs. 10.1%, p = 0.21; PUL 1.2 total score: 2.3 vs. 3.8 units, p = 0.20). More than half of patients experienced clinically significant deficits in FVC %-predicted and PUL 1.2 before experiencing LoA. Among subjects with baseline 10MWR >10 s, those with <1 year to LoA had similar mean ages but significantly worse mean ambulatory function at baseline compared to those with ≥1 year to LoA. Enriching DMD clinical trials for patients with declining pulmonary or upper limb function is achievable without restricting enrollment to non-ambulatory patients. The sequencing of LoA and initial deficits in pulmonary and upper limb function varied across patients and highlights the potential for composite outcomes or multi-outcome trial designs to assess disease-modifying therapies more comprehensively.

Functional abilities, respiratory and cardiac function in a large cohort of adults with Duchenne muscular dystrophy treated with glucocorticoids

BACKGROUND AND PURPOSE

The transition to adult services, and subsequent glucocorticoid management, is critical in adults with Duchenne muscular dystrophy. This study aims (1) to describe treatment, functional abilities, respiratory and cardiac status during transition to adulthood and adult stages; and (2) to explore the association between glucocorticoid treatment after loss of ambulation (LOA) and late-stage clinical outcomes.

METHODS

This was a retrospective single-centre study on individuals with Duchenne muscular dystrophy (≥16 years old) between 1986 and 2022. Logistic regression, Cox proportional hazards models and survival analyses were conducted utilizing data from clinical records.

RESULTS

In all, 112 individuals were included. Mean age was 23.4 ± 5.2 years and mean follow-up was 18.5 ± 5.5 years. At last assessment, 47.2% were on glucocorticoids; the mean dose of prednisone was 0.38 ± 0.13 mg/kg/day and of deflazacort 0.43 ± 0.16 mg/kg/day. At age 16 years, motor function limitations included using a manual wheelchair (89.7%), standing (87.9%), transferring from a wheelchair (86.2%) and turning in bed (53.4%); 77.5% had a peak cough flow <270 L/min, 53.3% a forced vital capacity percentage of predicted <50% and 40.3% a left ventricular ejection fraction <50%. Glucocorticoids after LOA reduced the risk and delayed the time to difficulties balancing in the wheelchair, loss of hand to mouth function, forced vital capacity percentage of predicted <30% and forced vital capacity <1 L and were associated with lower frequency of left ventricular ejection fraction <50%, without differences between prednisone and deflazacort. Glucocorticoid dose did not differ by functional, respiratory or cardiac status.

CONCLUSION

Glucocorticoids after LOA preserve late-stage functional abilities, respiratory and cardiac function. It is suggested using functional abilities, respiratory and cardiac status at transition stages for adult services planning.

"You Take This Day by Day, Come What May": A Qualitative Study of the Psychosocial Impacts of Living with Duchenne Muscular Dystrophy

INTRODUCTION

Studies have reported health-related quality-of-life impacts of Duchenne muscular dystrophy (DMD); however, further research is needed to understand how those with DMD experience their condition and how psychosocial impacts evolve over time in response to disease progression. This qualitative study explores the social and emotional implications of key transitions, challenges and adaptations throughout the disease course from the perspective of patients and family caregivers.

METHODS

Semi-structured interviews were conducted with men and boys with DMD, and/or their caregivers, in the USA. Thematic analysis was used to examine patterns in data collected across the interviews.

RESULTS

Nineteen participants were included. Three major themes were identified: (1) barriers to participation are multifaceted; (2) an emotional journey shaped by 'inevitable progression;' (3) family provides critical tangible and emotional support. This study illustrates that psychosocial impacts of DMD are shaped by knowledge of the condition's natural history alongside other factors including the extent of social barriers, personal growth and adaptation, and family support.

CONCLUSIONS

Findings provide insight into the strength and resilience with which individuals and their families respond to daily challenges and major clinical milestones and highlight the relative importance of loss of upper limb function as a transition in DMD affecting health-related quality-of-life.

Long-term clinical follow-up of a family with Becker muscular dystrophy associated with a large deletion in the DMD gene

Duchenne muscular dystrophy is a neuromuscular disease caused by DMD gene mutations that result in an absence of functional dystrophin protein. Patients with Duchenne experience progressive muscle weakness, are typically wheelchair dependent by their early teens, and develop respiratory and cardiac complications that lead to death in their twenties or thirties. Becker muscular dystrophy is also caused by DMD gene mutations, but symptoms are less severe and progression is slower compared with Duchenne. We describe a case study of a patient with Becker muscular dystrophy who was still ambulant at age 61 years and had a milder phenotype than Duchenne, despite 46% of his DMD gene being missing. His affected relatives had similarly mild phenotypes and clinical courses. These data guided the understanding of the criticality of various regions of dystrophin and informed the development of micro-dystrophin constructs to compensate for the absence of functional dystrophin in Duchenne.