Meaningful changes in motor function in Duchenne muscular dystrophy (DMD): A multi-center study.

Evaluations of treatment efficacy in Duchenne muscular dystrophy (DMD), a rare genetic disease that results in progressive muscle wasting, require an understanding of the 'meaningfulness' of changes in functional measures. We estimated the minimal detectable change (MDC) for selected motor function measures in ambulatory DMD, i.e., the minimal degree of measured change needed to be confident that true underlying change has occurred rather than transient variation or measurement error. MDC estimates were compared across multiple data sources, representing >1000 DMD patients in clinical trials and real-world clinical practice settings. Included patients were ambulatory, aged ≥4 to <18 years and receiving steroids. Minimal clinically important differences (MCIDs) for worsening were also estimated. Estimated MDC thresholds for >80% confidence in true change were 2.8 units for the North Star Ambulatory Assessment (NSAA) total score, 1.3 seconds for the 4-stair climb (4SC) completion time, 0.36 stairs/second for 4SC velocity and 36.3 meters for the 6-minute walk distance (6MWD). MDC estimates were similar across clinical trial and real-world data sources, and tended to be slightly larger than MCIDs for these measures. The identified thresholds can be used to inform endpoint definitions, or as benchmarks for monitoring individual changes in motor function in ambulatory DMD.

Quantifying the insurance value for rare diseases: Duchenne muscular dystrophy.

OBJECTIVES: To quantify the magnitude of an ISPOR novel value element, insurance value, as applied to new treatments for a rare, severe disease with pediatric onset: Duchenne muscular dystrophy (DMD). STUDY DESIGN: Prospective survey of individuals planning to have children in the future. METHODS: A survey was administered to US adults (aged ≥ 21 years) planning to have a child in the future to elicit willingness to pay (WTP) for insurance coverage for a new hypothetical DMD treatment that improved mortality and morbidity relative to the current standard of care. To identify an indifference point between status quo insurance and insurance with additional cost that would cover the treatment if respondents had a child with DMD, a multiple random staircase design was used. Insurance value-the value individuals receive from a reduction in future health risks-was calculated as the difference between respondent's WTP and what a risk-neutral individual would pay. The risk-neutral value was the product of the (1) probability of having a child with DMD (decision weighted), (2) quality-adjusted life-years (QALYs) gained from the new treatment, and (3) WTP per QALY. RESULTS: Among 207 respondents, 80.2% (n = 166) were aged 25 to 44 years, and 59.9% (n = 124) were women. WTP for insurance coverage of the hypothetical treatment was $973 annually, whereas the decision-weighted risk-neutral value was $452 per year. Thus, insurance value constituted 53.5% ($520) of value for new DMD treatments. CONCLUSIONS: Individuals planning to have children in the future are willing to pay more for insurance coverage of novel DMD treatments than is assumed under risk-neutral, QALY-based frameworks.

Essential components of an effective transition from paediatric to adult neurologist care for adolescents with Duchenne muscular dystrophy; a consensus derived using the Delphi methodology in Eastern Europe, Greece and Israel.

PURPOSE: An increasing number of patients with Duchenne muscular dystrophy (DMD) now have access to improved standard of care and disease modifying treatments, which improve the clinical course of DMD and extend life expectancy beyond 30 years of age. A key issue for adolescent DMD patients is the transition from paediatric- to adult-oriented healthcare. Adolescents and adults with DMD have unique but highly complex healthcare needs associated with long-term steroid use, orthopaedic, respiratory, cardiac, psychological, and gastrointestinal problems meaning that a comprehensive transition process is required. A sub-optimal transition into adult care can have disruptive and deleterious consequences for a patient's long-term care. This paper details the results of a consensus amongst clinicians on transitioning adolescent DMD patients from paediatric to adult neurologists that can act as a guide to best practice to ensure patients have continuous comprehensive care at every stage of their journey. METHODS: The consensus was derived using the Delphi methodology. Fifty-three statements were developed by a Steering Group (the authors of this paper) covering seven topics: Define the goals of transition, Preparing the patient, carers/parents and the adult centre, The transition process at the paediatric centre, The multidisciplinary transition summary - Principles, The multidisciplinary transition summary - Content, First visit in the adult centre, Evaluation of transition. The statements were shared with paediatric and adult neurologists across Central Eastern Europe (CEE) as a survey requesting their level of agreement with each statement. RESULTS: Data from 60 responders (54 full responses and six partial responses) were included in the data set analysis. A consensus was agreed across 100% of the statements. CONCLUSIONS: It is hoped that the findings of this survey which sets out agreed best practice statements, and the transfer template documents developed, will be widely used and so facilitate an effective transition from paediatric to adult care for adolescents with DMD.

Nutritional Issues among Children with Duchenne Muscular Dystrophy-Incidence of Deficiency and Excess Body Mass.

The progression of Duchenne muscular dystrophy (DMD)requires the assessment of nutritional disturbances at each stage of the disease. The purpose of this study was to assess the nutritional status in various ages of boys with DMD using screening and in-depth evaluation methods. Body composition by Dual X-ray Absorptiometry (DXA), basal metabolic rate (BMR) by indirect calorimetry, a questionnaire of nutritional status-Pediatric Nutrition Screening Tool (PNST)-and laboratory parameters were performed. In the cohort of 93 boys aged 8.54 (5.9-12.6 years), inappropriate nutritional status occurred in 41.8% of boys (underweight 11.8%, overweight 16.0%, and obesity 14.0%). In the 10-13 age group, the occurrence of overweight and underweight was the highest. Based on PNST, 15.1% of patients were at nutritional risk (≥2 points)-the most in the 14-17 age group (29%). A negative correlation was identified between PNST and z-scores of body weight, BMI, and FFMI (r Spearman = -0.49, -0.46, and -0.48, respectively; p < 0.05). There were no differences between BMR results from indirect calorimetry and calculations from the Schofield formula for any age group. In obese boys, the caloric requirement in indirect calorimetry was significantly lower than that indicated by the calculations according to the Schofield formula (p < 0.028). Inappropriate nutritional status occurred in almost half of the children with DMD. The age group in which nutritional disorders were most frequently identified was 10-13 years old. PNST could be considered a tool for screening malnutrition after testing a larger group of DMD patients.

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.

Deletion of Dux ameliorates muscular dystrophy in mdx mice by attenuating oxidative stress via Nrf2.

DUX4 has been widely reported in facioscapulohumeral muscular dystrophy, but its role in Duchenne muscular dystrophy (DMD) is unclear. Dux is the mouse paralog of DUX4. In Dux-/- mdx mice, forelimb grip strength test and treadmill test were performed, and extensor digitorum longus (EDL) contraction properties were measured to assess skeletal muscle function. Pathological changes in mice were determined by serum CK and LDH levels and muscle Masson staining. Inflammatory factors, oxidative stress, and mitochondrial function indicators were detected using kits. Primary muscle satellite cells were isolated, and the antioxidant molecule Nrf2 was detected. MTT assay and Edu assay were used to evaluate proliferation and TUNEL assay for cell death. The results show that the deletion of Dux enhanced forelimb grip strength and EDL contractility, prolonged running time and distance in mdx mice. Deleting Dux also attenuated muscle fibrosis, inflammation, oxidative stress, and mitochondrial dysfunction in mdx mice. Furthermore, Dux deficiency promoted proliferation and survival of muscle satellite cells by increasing Nrf2 levels in mdx mice.

A case study of Duchenne muscular dystrophy caused by Alu element insertion in DMD gene and analysis of its gray-hair symptoms.

Duchenne muscular dystrophy (DMD) is a severe X-linked recessive genetic disorder caused by mutations in the DMD gene, which leads to a deficiency of the dystrophin protein. The main mutation types of this gene include exon deletions and duplications, point mutations, and insertions. These mutations disrupt the normal expression of dystrophin, ultimately leading to the disease. In this study, we reported a case of DMD caused by an insertion mutation in exon 59 (E59) of the DMD gene. The affected child exhibited significant abnormalities in related biochemical markers, early symptoms of DMD, and multiple gray hair. His mother and sister were carriers with slightly abnormal biochemical markers. The mother had mild clinical symptoms, while the sister had no clinical symptoms. Other family members were genetically and physically normal. Sequencing and sequence alignment revealed that the inserted fragment was an Alu element from the AluYa5 subfamily. This insertion produced two stop codons and a polyadenylate (polyA) tail. To understand the impact of this insertion on the DMD gene and its association with clinical symptoms, exonic splicing enhancer (ESE) prediction indicated that the insertion did not affect the splicing of E59. Therefore, we speculated that the insertion sequence would be present in the mRNA sequence of the DMD gene. The two stop codons and polyA tail likely terminate translation, preventing the production of functional dystrophin protein, which may be the mechanism leading to DMD. In addition to typical DMD symptoms, the child also exhibited premature graying of hair. This study reports, for the first time, a case of DMD caused by the insertion of an Alu element into the coding region of the DMD gene. This finding provides clues for studying gene mutations induced by Alu sequence insertion and expands the understanding of DMD gene mutations.

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.

Adenine base editing-mediated exon skipping restores dystrophin in humanized Duchenne mouse model.

Duchenne muscular dystrophy (DMD) affecting 1 in 3500-5000 live male newborns is the frequently fatal genetic disease resulted from various mutations in DMD gene encoding dystrophin protein. About 70% of DMD-causing mutations are exon deletion leading to frameshift of open reading frame and dystrophin deficiency. To facilitate translating human DMD-targeting CRISPR therapeutics into patients, we herein establish a genetically humanized mouse model of DMD by replacing exon 50 and 51 of mouse Dmd gene with human exon 50 sequence. This humanized mouse model recapitulats patient's DMD phenotypes of dystrophin deficiency and muscle dysfunction. Furthermore, we target splicing sites in human exon 50 with adenine base editor to induce exon skipping and robustly restored dystrophin expression in heart, tibialis anterior and diaphragm muscles. Importantly, systemic delivery of base editor via adeno-associated virus in the humanized male mouse model improves the muscle function of DMD mice to the similar level of wildtype ones, indicating the therapeutic efficacy of base editing strategy in treating most of DMD types with exon deletion or point mutations via exon-skipping induction.

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.

Loss of endogenous estrogen alters mitochondrial metabolism and muscle clock-related protein Rbm20 in female mdx mice.

Female carriers of a Duchenne muscular dystrophy (DMD) gene mutation manifest exercise intolerance and metabolic anomalies that may be exacerbated following menopause due to the loss of estrogen, a known regulator of skeletal muscle function and metabolism. Here, we studied the impact of estrogen depletion (via ovariectomy) on exercise tolerance and muscle mitochondrial metabolism in female mdx mice and the potential of estrogen replacement therapy (using estradiol) to protect against functional and metabolic perturbations. We also investigated the effect of estrogen depletion, and replacement, on the skeletal muscle proteome through an untargeted proteomic approach with TMT-labelling. Our study confirms that loss of estrogen in female mdx mice reduces exercise capacity, tricarboxylic acid cycle intermediates, and citrate synthase activity but that these deficits are offset through estrogen replacement therapy. Furthermore, ovariectomy downregulated protein expression of RNA-binding motif factor 20 (Rbm20), a critical regulator of sarcomeric and muscle homeostasis gene splicing, which impacted pathways involving ribosomal and mitochondrial translation. Estrogen replacement modulated Rbm20 protein expression and promoted metabolic processes and the upregulation of proteins involved in mitochondrial dynamics and metabolism. Our data suggest that estrogen mitigates dystrophinopathic features in female mdx mice and that estrogen replacement may be a potential therapy for post-menopausal DMD carriers.

Smart Speakers as an Environmental Control Unit for Severe Motor Dependence: The Case of a Young Adult with Duchenne Muscular Dystrophy.

Duchenne muscular dystrophy (DMD) is a disease that primarily affects males and causes a gradual loss of muscle strength. This results in a deterioration of motor skills and functional mobility, which can impact the performance of various occupations. Individuals with DMD often rely heavily on caregivers to assist with daily activities, which can lead to caregiver burden. A case study was conducted to explore and describe potential variations in the performance of a young adult diagnosed with DMD and his caregivers resulting from the integration of smart speakers (SS)-controlled Internet of Things (IoT) devices in the home environment. The study also examined the potential of SS as an environment control unit (ECU) and analysed variations in caregiver burden. Smart devices and SS were installed in the most frequently used spaces, namely, the bedroom and living room. The study employed WebQDA software to perform content analysis and Microsoft Excel to calculate the scores of the structured instruments. The implementation of the IoT-assisted environment compensated for previously physical tasks, resulting in a slight increase in independent performance and reduced demands on caregivers.

Interplay between Pitx2 and Pax7 temporally governs specification of extraocular muscle stem cells.

Gene regulatory networks that act upstream of skeletal muscle fate determinants are distinct in different anatomical locations. Despite recent efforts, a clear understanding of the cascade of events underlying the emergence and maintenance of the stem cell pool in specific muscle groups remains unresolved and debated. Here, we invalidated Pitx2 with multiple Cre-driver mice prenatally, postnatally, and during lineage progression. We showed that this gene becomes progressively dispensable for specification and maintenance of the muscle stem (MuSC) cell pool in extraocular muscles (EOMs) despite being, together with Myf5, a major upstream regulator during early development. Moreover, constitutive inactivation of Pax7 postnatally led to a greater loss of MuSCs in the EOMs compared to the limb. Thus, we propose a relay between Pitx2, Myf5 and Pax7 for EOM stem cell maintenance. We demonstrate also that MuSCs in the EOMs adopt a quiescent state earlier that those in limb muscles and do not spontaneously proliferate in the adult, yet EOMs have a significantly higher content of Pax7+ MuSCs per area pre- and post-natally. Finally, while limb MuSCs proliferate in the mdx mouse model for Duchenne muscular dystrophy, significantly less MuSCs were present in the EOMs of the mdx mouse model compared to controls, and they were not proliferative. Overall, our study provides a comprehensive in vivo characterisation of MuSC heterogeneity along the body axis and brings further insights into the unusual sparing of EOMs during muscular dystrophy.

Targeted Antisense Oligonucleotide-Mediated Skipping of Murine Postn Exon 17 Partially Addresses Fibrosis in D2.mdx Mice.

Periostin, a multifunctional 90 kDa protein, plays a pivotal role in the pathogenesis of fibrosis across various tissues, including skeletal muscle. It operates within the transforming growth factor beta 1 (Tgf-ß1) signalling pathway and is upregulated in fibrotic tissue. Alternative splicing of Periostin's C-terminal region leads to six protein-coding isoforms. This study aimed to elucidate the contribution of the isoforms containing the amino acids encoded by exon 17 (e17+ Periostin) to skeletal muscle fibrosis and investigate the therapeutic potential of manipulating exon 17 splicing. We identified distinct structural differences between e17+ Periostin isoforms, affecting their interaction with key fibrotic proteins, including Tgf-ß1 and integrin alpha V. In vitro mouse fibroblast experimentation confirmed the TGF-ß1-induced upregulation of e17+ Periostin mRNA, mitigated by an antisense approach that induces the skipping of exon 17 of the Postn gene. Subsequent in vivo studies in the D2.mdx mouse model of Duchenne muscular dystrophy (DMD) demonstrated that our antisense treatment effectively reduced e17+ Periostin mRNA expression, which coincided with reduced full-length Periostin protein expression and collagen accumulation. The grip strength of the treated mice was rescued to the wild-type level. These results suggest a pivotal role of e17+ Periostin isoforms in the fibrotic pathology of skeletal muscle and highlight the potential of targeted exon skipping strategies as a promising therapeutic approach for mitigating fibrosis-associated complications.

Severe gastrointestinal problems in Duchenne muscular dystrophy: A case series.

Due to improved supportive care, survival of patients with Duchenne muscular dystrophy (DMD) has increased significantly. Consequently, new challenges emerge in adult patients with DMD. In clinical practice we increasingly see patients with serious, even life-threatening, gastrointestinal (GI) problems in advanced disease stages. Little is known about the longitudinal course of GI problems and the appropriate management. We present a case-series of six adult patients with DMD with (recurrent) GI problems that required hospital admission. The most prevalent reported serious GI symptoms were gastrointestinal pseudo-obstruction, (sub)ileus and gastric dilatation. Besides, an overview is presented of the therapeutic options for GI problems in DMD. The current study provides insight in possible treatment options, however, there is a clear need for more research and an integral guideline on treatment of GI problems in adult patients with DMD in order to reduce associated morbidity and mortality.

Targeted expression of heme oxygenase-1 in satellite cells improves skeletal muscle pathology in dystrophic mice.

BACKGROUND: Adult muscle-resident myogenic stem cells, satellite cells (SCs), that play non-redundant role in muscle regeneration, are intrinsically impaired in Duchenne muscular dystrophy (DMD). Previously we revealed that dystrophic SCs express low level of anti-inflammatory and anti-oxidative heme oxygenase-1 (HO-1, HMOX1). Here we assess whether targeted induction of HMOX1 affect SC function and alleviates hallmark symptoms of DMD. METHODS: We generated double-transgenic mouse model (mdx;HMOX1Pax7Ind) that allows tamoxifen (TX)-inducible HMOX1 expression in Pax7 positive cells of dystrophic muscles. Mdx;HMOX1Pax7Ind and control mdx mice were subjected to 5-day TX injections (75 mg/kg b.w.) followed by acute exercise protocol with high-speed treadmill (12 m/min, 45 min) and downhill running to worsen skeletal muscle phenotype and reveal immediate effects of HO-1 on muscle pathology and SC function. RESULTS: HMOX1 induction caused a drop in SC pool in mdx;HMOX1Pax7Ind mice (vs. mdx counterparts), while not exaggerating the effect of physical exercise. Upon physical exercise, the proliferation of SCs and activated CD34- SC subpopulation, was impaired in mdx mice, an effect that was reversed in mdx;HMOX1Pax7Ind mice, however, both in vehicle- and TX-treated animals. This corresponded to the pattern of HO-1 expression in skeletal muscles. At the tissue level, necrotic events of selective skeletal muscles of mdx mice and associated increase in circulating levels of muscle damage markers were blunted in HO-1 transgenic animals which showed also anti-inflammatory cytokine profile (vs. mdx). CONCLUSIONS: Targeted expression of HMOX1 plays protective role in DMD and alleviates dystrophic muscle pathology.