Consensus on the diagnosis, treatment and follow-up of patients with Duchenne muscular dystrophy

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.

Family Involvement and at-Home Physical Therapy on Duchenne Muscular Dystrophy: A Randomized Controlled Trial

BACKGROUND

Duchenne muscular dystrophy (DMD) is a genetic condition that causes muscle weakness and begins in early childhood. To treat its complications, the rehabilitation program includes physical therapy, mainly on the musculoskeletal and the respiratory complications that appear on the evolution of the disease. This study aims to explore the effects of physical therapy with or without an at-home program on motor function among children with DMD.

METHODS

A randomized controlled trial was carried out for one year (one group with at-home and conventional physical therapy and another with conventional physical therapy). Motor function was measured using the Motor Function Measure (MFM) scale, the Vignos and Brooke scales, the Timed-up-and-Go test, and the six-minute walk distance test.

RESULTS

Twenty-seven participants with DMD participated in this study. In the at-home and conventional physical therapy group, better motor function at the distal and global level was maintained, per the results of the MFM scale (P < 0.05). The rest of the variables did not achieve statistically significant changes.

CONCLUSIONS

Our results suggest that complementing conventional treatment with at-home treatment in which the family is involved maintains better motor function, in participants with DMD.

Clinical practice guidelines for the diagnosis and management of Duchenne muscular dystrophy: a scoping review

Introduction

Our objective was to identify recent CPGs for the diagnosis and management of DMD and summarize their characteristics and reliability.

Methods

We conducted a scoping review of CPGs using MEDLINE, the Turning Research Into Practice (TRIP) database, Google Scholar, guidelines created by organizations, and other repositories to identify CPGs published in the last 5 years. Our protocol was drafted using the Preferred Reporting Items for Systematic Reviews and Meta-analyses for scoping reviews. To assess the reliability of the CPGs, we used all the domains included in the Appraisal of Guidelines Research and Evaluation II.

Results

We selected three CPGs published or updated between 2015 and 2020. All the guidelines showed good or adequate methodological rigor but presented pitfalls in stakeholder involvement and applicability domains. Recommendations were coherent across CPGs on steroid treatment, except for minor differences in dosing regimens. However, the recommendations were different for new drugs.

Discussion

There is a need for current and reliable CPGs that develop broad topics on the management of DMD and consider the challenges of developing recommendations for RDs.

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.

Confirmatory validation of the french version of the Duchenne Muscular Dystrophy module of the pediatric quality of life inventory (PedsQLTM3.0DMDfv)

Duchenne Muscular Dystrophy (DMD) is a neuromuscular disease that inevitably leads to total loss of autonomy. The new therapeutic strategies aim to both improve survival and optimise quality of life. Evaluating quality of life is nevertheless a major challenge. No DMD-specific quality of life scale to exists in French. We therefore produced a French translation of the English Duchenne Muscular Dystrophy module of the Pediatric Quality of Life Inventory (PedsQLTMDMD) following international recommendations. The study objective was to carry out a confirmatory validation of the French version of the PedsQLTMDMD for paediatric patients with DMD, using French multicentre descriptive cross-sectional data. The sample consisted of 107 patients. Internal consistency was acceptable for proxy-assessments, with Cronbach's alpha coefficients above 0.70, except for the Treatment dimension. For self-assessments, internal consistency was acceptable only for the Daily Activities dimension. Our results showed poor metric qualities for the French version of the PedsQLTMDMD based on a sample of about 100 children, but these results remained consistent with those of the original validation. This confirms the interest of its use in clinical practice.

Assessing the value of delandistrogene moxeparvovec (SRP-9001) gene therapy in patients with Duchenne muscular dystrophy in the United States

Background: Delandistrogene moxeparvovec (SRP-9001) is an investigational gene therapy that may delay progression of Duchenne muscular dystrophy (DMD), a severe, rare neuromuscular disease caused by DMD gene mutations. Early cost-effectiveness analyses are important to help contextualize the value of gene therapies for reimbursement decision making. Objective: To determine the potential value of delandistrogene moxeparvovec using a cost-effectiveness analysis. Study design: A simulation calculated lifetime costs and equal value of life years gained (evLYG). Inputs included extrapolated clinical trial results and published utilities/costs. As a market price for delandistrogene moxeparvovec has not been established, threshold analyses established maximum treatment costs as they align with value, including varying willingness-to-pay up to $500,000, accounting for severity/rarity. Setting: USA, healthcare system perspective Patients: Boys with DMD Intervention: Delandistrogene moxeparvovec plus standard of care (SoC; corticosteroids) versus SoC alone Main outcome measure: Maximum treatment costs at a given willingness-to-pay threshold Results: Delandistrogene moxeparvovec added 10.30 discounted (26.40 undiscounted) evLYs. The maximum treatment cost was approximately $5 M, assuming $500,000/evLYG. Varying the benefit discount rate to account for the single administration increased the estimated value to #$5M, assuming $500,000/evLYG. Conclusion: In this early economic model, delandistrogene moxeparvovec increases evLYs versus SoC and begins to inform its potential value from a healthcare perspective.

Longitudinal study of multi-parameter quantitative magnetic resonance imaging in Duchenne muscular dystrophy: hyperresponsiveness of gluteus maximus and detection of subclinical disease progression in functionally stable patients

OBJECTIVE

To describe the disease progression of Duchenne muscular dystrophy (DMD) in the pelvic and thigh muscles over 1-year using multiple-parameter quantitative magnetic resonance imaging (qMRI), and to determine the most responsive muscle and predict subclinical disease progression in functionally stable patients.

METHODS

Fifty-four DMD patients (mean age 8.9 ± 2.5, range 5-15 years) completed baseline and 1-year follow-up qMRI examinations/biomarkers [3-point Dixon/fat fraction (FF); T1 mapping/T1; T2 mapping/T2]. Meanwhile, clinical assessments [NorthStar ambulatory assessment (NSAA) score] and timed function tests were performed in DMD patients. Twenty-four healthy male controls (range 5-15 years) accomplished baseline qMRI examinations. Group differences were compared using the Wilcoxon test. The standardized response mean (SRM) was taken as the responsiveness to the disease progression index.

RESULTS

FF, T1, and T2 in all DMD age subgroups changed significantly over 1-year (P < 0.05). Even in functionally stable patients (NSAA score increased, unchanged, or decreased by 1-point) over 1-year, significant increases in FF and T2 and decreases in T1 were observed in gluteus maximus (GMa), gluteus medius, vastus lateralis, and adductor magnus (P < 0.05). Overall, the SRM of FF, T1, and T2 was all the highest in GMa, which were 1.25, - 0.92, and 0.93, respectively.

CONCLUSIONS

qMRI biomarkers are responsive to disease progression and can also detect subclinical disease progression in functionally stable DMD patients over 1-year. GMa is the most responsive to disease progression of all the muscles analyzed.

TRIAL REGISTRATION

Chinese Clinical Trial Registry ( http://www.chictr.org.cn/index.aspx ) ChiCTR1800018340, 09/12/2018, prospectively registered.

Analysis of Long Noncoding RNAs-Related Regulatory Mechanisms in Duchenne Muscular Dystrophy Using a Disease-Related lncRNA-mRNA Pathway Network

Objective

This study aimed to investigate the molecular regulatory mechanisms underpinning Duchenne muscular dystrophy (DMD).

Methods

Using microarray data, differentially expressed long noncoding RNAs (DELs) and DMD-related differentially expressed mRNAs (DEMs) were screened based on the comparative toxicogenomics database, using a cutoff of |log₂ fold change| > 1 and false discovery rate (FDR) < 0.05. Then, protein-protein interaction (PPI), coexpression network of lncRNA-mRNA, and DMD-related lncRNA-mRNA pathway networks were constructed, and functional analyses of the genes in the network were performed. Finally, the proportions of immune cells infiltrating the muscle tissues in DMD were analyzed, and the correlation between the immune cells and expression of the DELs/DEMs was studied.

Results

A total of 46 DELs and 313 DMD-related DEMs were identified. The PPI network revealed STAT1, VEGFA, and CCL2 to be the top three hub genes. The DMD-related lncRNA-mRNA pathway network comprising two pathways, nine DELs, and nine DMD-related DEMs showed that PYCARD, RIPK2, and CASP1 were significantly enriched in the NOD-like receptor signaling pathway, whereas MAP2K2, LUM, RPS6, PDCD4, TWIST1, and HIF1A were significantly enriched with proteoglycans in cancers. The nine DELs in this network were DBET, MBNL1-AS1, MIR29B2CHG, CCDC18-AS1, FAM111A-DT, GAS5, LINC01290, ATP2B1-AS1, and PSMB8-AS1.

Conclusion

The nine DMD-related DEMs and DELs identified in this study may play important roles in the occurrence and progression of DMD through the two pathways of the NOD-like receptor signaling pathway and proteoglycans in cancers.

A qualitative exploration of the priorities and experiences of children with Duchenne muscular dystrophy, their parents, and healthcare professionals around weight management

PURPOSE

The quality and length of life for boys with Duchenne muscular dystrophy (DMD) has improved due to medical advancements, but obesity has emerged as and may pose a risk to their physical health. Clinical guidelines recommend attention to weight management, but healthcare professionals (HCPs) find implementing them in clinical care challenging. Little information is available about the perspectives of children with DMD and their families around weight management. This study explored the key priorities of children with DMD, their parents, and HCPs who treat them, around weight management.

METHODS

Qualitative, individual, semi-structured interviews were conducted and analyzed using a qualitative descriptive approach.

RESULTS

Participants included parents of children with DMD (n = 13), children with DMD (n = 10), and HCPs (n = 14). Theme one: "Competing priorities between healthcare providers, parents, and boys" contained two sub-themes: (i) Body mechanics and function; and (ii) Psychosocial well-being. Theme two: "The realities of living with Duchenne's Muscular Dystrophy," with subthemes: (i) Striving for normality; (ii) The trajectory of DMD; (iii) The labour associated with DMD.

CONCLUSION

HCPs, parents, and boys have diverging worldviews around weight management, highlighting the importance of integrating the priorities of families into care, even when not aligned with guideline recommendations.IMPLICATIONS FOR REHABILITATIONHCPs must understand the competing priorities in the lives of children with DMD and their families when discussing weight, weight management, and lifestyle changes.Quality of life and living a "normal" life are prioritized by children and families over the surveillance and time demands of lifestyle routines recommended by clinicians for weight management.Weight management recommendations should be based upon the individual needs and priorities of the family.

Utilization of T1-Mapping for the pelvic and thigh muscles in Duchenne Muscular Dystrophy: a quantitative biomarker for disease involvement and correlation with clinical assessments

BACKGROUND

Little is known about the disease distribution and severity detected by T1-mapping in Duchenne muscular dystrophy (DMD). Furthermore, the correlation between skeletal muscle T1-values and clinical assessments is less studied. Hence, the purposes of our study are to investigate quantitative T1-mapping in detecting the degree of disease involvement by detailed analyzing the hip and thigh muscle, future exploring the predicting value of T1-mapping for the clinical status of DMD.

METHODS

Ninety-two DMD patients were included. Grading fat infiltration and measuring the T1-values of 19 pelvic and thigh muscles (right side) in axial T1-weighted images (T1WI) and T1-maps, respectively, the disease distribution and severity were evaluated and compared. Clinical assessments included age, height, weight, BMI, wheelchair use, timed functional tests, NorthStar ambulatory assessment (NSAA) score, serum creatine kinase (CK) level. Correlation analysis were performed between the muscle T1-value and clinical assessments. Multiple linear regression analysis was conducted for the independent association of T1-value and motor function.

RESULTS

The gluteus maximus had the lowest T1-value, and the gracilis had the highest T1-value. T1-value decreased as the grade of fat infiltration increased scored by T1WI (P < 0.001). The decreasing of T1-values was correlated with the increase of age, height, weight, wheelchair use, and timed functional tests (P < 0.05). T1-value correlated with NSAA (r = 0.232-0.721, P < 0.05) and CK (r = 0.208-0.491, P < 0.05) positively. T1-value of gluteus maximus, tensor fascia, vastus lateralis, vastus intermedius, vastus medialis, and adductor magnus was independently associated with the clinical motor function tests (P < 0.05). Interclass correlation coefficient (ICC) analysis and Bland-Altman plots showed excellent inter-rater reliability of T1-value region of interest (ROI) measurements.

CONCLUSION

T1-mapping can be used as a quantitative biomarker for disease involvement, further assessing the disease severity and predicting motor function in DMD.

A Chinese boy with familial Duchenne muscular dystrophy owing to a novel hemizygous nonsense mutation (c.6283C>T) in an exon of the DMD gene

Duchenne muscular dystrophy is a severe, X-linked, progressive neuromuscular disorder clinically characterised by muscle weakening and extremely high serum creatine kinase levels. A 1-year-old Chinese patient was diagnosed with early-onset Duchenne muscular dystrophy. Next-generation gene sequencing was conducted and the Sanger method was used to validate sequencing. We identified a novel nonsense mutation (c.6283C>T) in DMD that caused the replacement of native arginine at codon 2095 with a premature termination codon (p.R2095X), which may have had a pathogenic effect against dystrophin in our patient’s muscle cell membranes. We discovered a novel nonsense mutation in DMD that will expand the pathogenic mutation spectrum for Duchenne muscular dystrophy.

[Update on Duchenne muscular dystrophy]

Duchenne muscular dystrophy, DMD*(ICD-9-C: 359.1; ICD-10-ES: G71.01, ORPHA: 98896) is a dystrophic type, autosomal recessive myopathy linked to the X chromosome, low incidence 1/3300, with full penetrance and multi-organ involvement (neuro-muscular, respiratory, digestive and metabolic). It has great clinical variability. Symptoms begin in pediatric age (mobility limitation and early respiratory complications). Respiratory complications reduce the life expectancy of those affected. There is no treatment that modifies its evolution, although corticosteroids and new gene therapies are increasing the half-life of this disease. The role of the Primary Care Physician (PCP) is decisive in the monitoring and control of the complications of DMD, either coordinating the different specialties involved in it.

Nanomedicine for Gene Delivery and Drug Repurposing in the Treatment of Muscular Dystrophies

Muscular Dystrophies (MDs) are a group of rare inherited genetic muscular pathologies encompassing a variety of clinical phenotypes, gene mutations and mechanisms of disease. MDs undergo progressive skeletal muscle degeneration causing severe health problems that lead to poor life quality, disability and premature death. There are no available therapies to counteract the causes of these diseases and conventional treatments are administered only to mitigate symptoms. Recent understanding on the pathogenetic mechanisms allowed the development of novel therapeutic strategies based on gene therapy, genome editing CRISPR/Cas9 and drug repurposing approaches. Despite the therapeutic potential of these treatments, once the actives are administered, their instability, susceptibility to degradation and toxicity limit their applications. In this frame, the design of delivery strategies based on nanomedicines holds great promise for MD treatments. This review focuses on nanomedicine approaches able to encapsulate therapeutic agents such as small chemical molecules and oligonucleotides to target the most common MDs such as Duchenne Muscular Dystrophy and the Myotonic Dystrophies. The challenge related to in vitro and in vivo testing of nanosystems in appropriate animal models is also addressed. Finally, the most promising nanomedicine-based strategies are highlighted and a critical view in future developments of nanomedicine for neuromuscular diseases is provided.