Duchenne Muscular Dystrophy Research Articles

‘More than a just a physical condition’ – recognising the educational and emotional needs of children and young adults with duchenne muscular dystrophy

ABSTRACT Advances in medical care have seen children and young people with rare and life shortening conditions, living longer. This is the case for those living with Duchenne Muscular Dystrophy, whose life expectancy has doubled over the last few decades from around 20 to 40 years. Improving care has tended to focus on the physical aspects of the condition, rather than on wider psycho-social needs, such as social, cultural, psychological, educational, and emotional needs. Individuals with DMD are likely to have higher rates of neurodivergence and mental health diagnoses, and this, coupled with increased life expectancy, requires an urgent focus on how schools and colleges support the non-physical needs of pupils with DMD. We discuss existing research on DMD and education, before reporting findings from a small-scale mixed-methods study that explored parents views of their children’s experiences in education and that of two adults living with DMD. The findings revealed three main themes: lack of understanding of non-physical needs; lack of support and under-resourced systems; and strategies that work – a hopeful approach. We conclude that established educational and emotional aspects of DMD are often unacknowledged in schools and that ableism and societal assumptions about lifespan can affect education provision.

Upper body gait deviations in children with Duchenne muscular dystrophy

BackgroundDuchenne 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. MethodsKinematic 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). FindingsDuchenne 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. InterpretationIncluding 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.

Concordance between parental and self-rated and performance-based measures of executive functioning in boys with Duchenne muscular dystrophy: the role of parental life satisfaction and carrier versus non-carrier status

ABSTRACT The aim of this study was to examine the concordance between parental and self-rated and performance-based tests of executive function in boys with Duchenne muscular dystrophy (DMD). A secondary aim was to explore how this concordance is related to parents’ self-rated life satisfaction and status as a carrier mother versus non-carrier mother. In a cross-sectional study design, 70 boys with DMD, aged 5–14, and their parents were included. Results indicated no significant correlation between performance-based measures and parental or self-rated assessments of executive function (EF). However, parents with low life satisfaction and/or carrier status rated their child’s EF skills significantly lower. But self-rated life satisfaction did not correlate with status as a carrier mother or the performance-based measures of the boys’ and the boys’ performance-based EF skills did not correlate with either their parents’ life satisfaction or status as a carrier mother. These findings indicate that the two sources of information may not measure the same construct. One possible explanation for this is that our data supports the framework of hot and cold executive function (EF) skills and that these EF skills must be identified using different methods. Another possible explanation could be that parental ratings of child EF skills may also include measurement of carrier burden, parents EF skills, and the families’ abilities for psychosocial adjustments in everyday life.

Genotype and corticosteroid treatment are distinctively associated with gray matter characteristics in patients with Duchenne muscular dystrophy

This study investigated if structural variation in specific gray matter areas is associated with corticosteroid treatment or genotype, and if cerebral morphological variations are related to neuropsychological and behavioral outcomes.The CAT12 toolbox in SPM was used for MRI segmentations, assessing subcortical structures, cortical thickness, gyrification, and sulci depths for DMD patients (n=40; 9-18 years) and age-matched controls (n=40). Comparisons were made between DMD vs. controls, daily vs. intermittent corticosteroid treatment (n=20 each), and Dp140+ vs. Dp140- gene mutations (n=15 vs. 25). MANCOVA, CAT12 3D statistics and Pearson correlations were conducted.DMD patients showed differences in volumes of distinct subcortical structures, left hemisphere cortical thickness, and gyrification in multiple brain areas compared with healthy controls. The daily treated DMD group exhibited differences in subcortical volumes and different patterns of cortical thickness, sulci depth, and gyrification compared to the intermittent treated DMD group. DMD Dp140+ patients displayed altered gyrification and sulci depth compared to DMD Dp140- patients. Finally, we found correlations between neurobehavioral outcomes and brain areas that showed differences in cortical morphology associated with corticosteroid treatment.Both genotype and corticosteroid treatment are associated with variations in subcortical volumes and cortical morphology, albeit in different ways. Corticosteroid treatment appears to have a more profound association with differences in gray matter characteristics of brain regions that are associated with functional outcomes.

Golodirsen restores DMD transcript imbalance in Duchenne Muscular Dystrophy patient muscle cells

BackgroundAntisense oligonucleotides (AON) represent a promising treatment for Duchenne muscular dystrophy (DMD) carrying out-of-frame deletions, but also show limitations. In a completed clinical trial golodirsen, approved by FDA to induce skipping of DMD gene exon 53 in eligible patients, we demonstrated increase in DMD expression and protein production, albeit with inter-patient variability.MethodsHere, we investigate further the golodirsen mechanism of action using myotubes derived from MyoD transfected fibroblasts isolated from DMD patients at the baseline of the clinical trial SRP-4053.ResultsWe confirm golodirsen’s selectivity and efficiency in removing only exon 53. For the first time in human cells, we revealed a significant reduction in the so called DMD “transcript imbalance”, in golodirsen-treated DMD muscle cultures. The transcript imbalance is a unique DMD phenomenon characterized by non-homogeneous transcript expression along its entire length and responsible for the reduced stability of the transcript. Our in-vivo study also showed that the efficiency of exon skipping did not always correspond to a proportional restoration of the dystrophin protein. Predominant nuclear localization of the DMD transcript, observed in patients and animal models, persists even after exon skipping.ConclusionAll these findings suggest challenges other than AON delivery for high level of protein restoration in DMD, highlighting the importance of investigating the biological mechanisms upstream of protein production to further enhance the efficiency of any AON treatment in this condition.

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.

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

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

MRI-Based Circumferential Strain in Boys with Early Duchenne Muscular Dystrophy Cardiomyopathy

Background: In boys with Duchenne muscular dystrophy (DMD), cardiomyopathy has become the primary cause of death. Although both positive late gadolinium enhancement (LGE) and reduced left ventricular ejection fraction (LVEF) are late findings in a DMD cohort, LV end-systolic circumferential strain at middle wall (Ecc) serves as a biomarker for detecting early impairment in cardiac function associated with DMD. However, Ecc derived from cine Displacement Encoding with Stimulated Echoes (DENSE) has not been quantified in boys with DMD. We aim to: (1) use cine DENSE to quantify regional Ecc in LGE negative (-) boys with DMD and healthy controls; and (2) compare Ecc with LVEF in terms of differentiating DMD boys with LGE (-) from healthy boys. Methods: 10 LGE (-) boys with DMD and 12 healthy boys were enrolled prospectively in an IRB-approved study for CMR at 3T. Navigator-gated cine DENSE was used to obtain short-axis mid-ventricular data and estimate global and regional Ecc. Group-wise differences were tested via a Wilcoxon rank-sum test. Within-group differences were tested via a Skillings-Mack test followed by pairwise Wilcoxon signed-rank tests. A binomial logistic regression model was adopted to differentiate between DMD boys with LGE (-) and healthy boys. Results: When compared to healthy boys, LGE (-) boys with DMD demonstrated significantly impaired septal Ecc [−0.13 (0.01) vs. −0.16 (0.03), p = 0.019]. In comparison to the Ecc in other segments, both groups of boys exhibited significantly reduced septal Ecc and significantly elevated lateral Ecc. Septal Ecc outperformed LVEF in distinguishing DMD boys with LGE (-) from healthy boys. Conclusions: Reduced septal Ecc may serve as an early indicator of cardiac involvement in LGE (-) DMD boys prior to reduced LVEF and a positive LGE finding.

The Future of Pediatric Care: AI and ML as Catalysts for Change in Genetic Syndrome Management

This review explores the significant impact of Artificial Intelligence (AI) and Machine Learning (ML) on pediatric healthcare and education for children with genetic syndromes. Our investigation shows that AI-driven tools, like Google AI's DeepVariant, have greatly improved diagnostic precision. This allows for earlier and more accurate identification of genetic anomalies in conditions such as Cri-du-Chat Syndrome and 22q11.2 Deletion Syndrome. In addition, ML-based approaches have played a crucial role in advancing personalized treatment strategies, such as utilizing pharmacogenomic models to optimize drug therapies for Duchenne Muscular Dystrophy. Adaptive learning platforms, such as DreamBox Learning, have effectively tailored educational content according to the specific requirements of children with syndromes like Phelan-McDermid Syndrome. The review suggests that combining AI and ML significantly enhances diagnostic accuracy, treatment effectiveness, and educational results, thereby establishing higher benchmarks for pediatric care. Nevertheless, these advancements have notable ethical, legal, and social challenges. It is essential to prioritize equitable access, data privacy protection, and algorithmic transparency to maximize the benefits and minimize potential risks associated with AI. Overall, the findings underscore the potential of AI and ML to revolutionize pediatric genetic care, provided that these technologies are implemented responsibly and inclusively.

Caregiver Global Impression Observations from EMBARK: A Phase 3 Study Evaluating Delandistrogene Moxeparvovec in Ambulatory Patients with Duchenne Muscular Dystrophy.

Duchenne muscular dystrophy (DMD) is a rare, progressive, debilitating neuromuscular disease. The early childhood onset and debilitating nature of the disease necessitate decades of caretaking for most patients. Caregivers have a critical role in evaluating patients' physical functioning and/or response to treatment. Using DMD-specific caregiver-reported scales, the impact of delandistrogene moxeparvovec gene therapy on caregivers' perceived change in patient disease status or severity was evaluated using the Caregiver Global Impression of Change and Severity (CaGI-C and CaGI-S, respectively). In the Phase 3 randomized, double-blind, placebo-controlled trial (EMBARK; NCT05096221), the CaGI-C at week 52 and change from baseline to week 52 in CaGI-S were evaluated in a post hoc analysis. The CaGI-C assesses caregivers' impressions of change in DMD symptoms, physical ability, ability to perform daily activities, and overall health. The CaGI-S evaluates current severity of DMD symptoms, physical ability, ability to perform activities of daily living, and overall health. Data were evaluated using multi-domain responder index (MDRI) and ordinal regression analyses. MDRI analyses across all four CaGI-C items yielded a treatment difference of 1.7 (95% confidence interval [CI]: 0.90-2.5) favoring delandistrogene moxeparvovec; a treatment difference of 1.1 (95% CI 0.30-1.9) was observed for the CaGI-S favoring delandistrogene moxeparvovec. After adjusting for age, ordinal regression analysis showed a nominally significant increase in the odds of achieving a better rating for delandistrogene moxeparvovec-treated patients on all four CaGI-C items (≥ 3.8-fold increase). After adjusting for baseline severity and age, ordinal regression analysis showed a nominally significant increase in the odds of improvement on all four CaGI-S items (≥ 2.2-fold increase). These exploratory findings captured by caregiver-reported outcomes add to the totality of evidence that supports the clinical benefits of delandistrogene moxeparvovec for patients with DMD. ClinicalTrials.gov identifier, NCT05096221.

GSK3 inhibition improves skeletal muscle function and whole-body metabolism in male mouse models of Duchenne muscular dystrophy

Inhibiting glycogen synthase kinase 3 (GSK3) improves muscle function, metabolism, and bone health in many diseases and conditions; however, whether GSK3 should be targeted for Duchenne muscular dystrophy (DMD), a severe muscle wasting disorder with no cure, remains unknown. Here, we show the effects of GSK3 inhibition in male DBA/2J (D2) and C57BL/10 (C57) mdx mice. Treating D2 mdx mice with GSK3 inhibitors alone or in combination with aerobic exercise improves muscle strength, endurance, and morphology, attenuates the hypermetabolic phenotype, and enhances insulin sensitivity. GSK3 inhibition in C57 mdx mice also improves muscle fatigue resistance and increases cage ambulation. Moreover, muscle-specific GSK3 knockdown in mdx mice augments muscle force production and endurance. In both mdx strains, GSK3 inhibition increases bone mineral content and density. Overall, these improvements to muscle, metabolic, and bone health with GSK3 inhibition in mdx mice may have clinical implications for patients with DMD, where the current standard of care, glucocorticoids, delay the loss of ambulation but increase the risk for insulin resistance and osteoporosis. Along with our observation of lowered β-catenin content in DMD myoblasts, a known cellular target for GSK3, this study provides ample evidence in support of inhibiting GSK3 for this disease.

Unexpected Findings of Duchenne Muscular Dystrophy in Prenatal Screening of Chromosome Abnormality Based on Cell-Free Fetal DNA.

This study aims to assess the feasibility of detecting and diagnosing Duchenne muscular dystrophy (DMD) during prenatal screening for chromosome abnormalities using cell-free fetal DNA extracted from peripheral blood samples of pregnant women. Two pregnant women identified as high risk through noninvasive prenatal testing (NIPT) underwent amniocentesis to obtain fetal cells. Subsequent fetal chromosomal karyotyping was conducted, and genomic DNA from fetal cells was extracted for copy number variation sequencing (CNV-Seq) analysis, complemented by multiplex ligation-dependent probe amplification (MLPA) to detect deletions or duplications within the DMD gene. NIPT results for the two samples indicated potential abnormalities involving chromosomes 21 and 18. However, karyotype analysis of the fetuses revealed no abnormalities. CNV-Seq identified deletions of 0.28 and 0.18 Mb within chromosome Xp21.1, encompassing the DMD gene, in each fetus. In family 1, MLPA results indicated a maternal heterozygous deletion spanning exons 12 to 41 in the DMD gene, while the fetus exhibited deletions in exons 12 to 41. In family 2, MLPA results confirmed normal DMD gene status in the pregnant woman's peripheral blood genomic DNA but revealed a fetal deletion spanning exons 48 to 52. Both fetuses were diagnosed with DMD and subsequently underwent termination. Abnormalities identified through NIPT necessitate further invasive prenatal diagnostic procedures. For cases involving chromosomal microdeletions or microduplications, a combination of karyotyping and CNV-Seq testing is essential for comprehensive diagnosis. NIPT followed by CNV-Seq may offer insights into large exon deletions within the DMD gene in specific instances. · NIPT results can offer valuable insights into the deletion and duplication of DMD gene for the fetus.. · It's crucial to notice unexpected findings in NIPT.. · A combination of karyotyping and CNV-Seq testing is essential for comprehensive diagnosis..

Duchenne Muscular Dystrophy (DMD) and Becker Muscular Dystrophy (BMD): A Review on Assessing Measures

Mutations in the encoding Dystrophin gene lead to lethal, genetic muscular dystrophies such as Duchenne Muscular Dystrophy (DMD), and Becker Muscular Dystrophy (BMD) which have a slower progression than DMD and an intermediate form. Dystrophin gene mutations abolish the production of Dystrophin in body muscles such as skeletal, cardiac, and smooth muscles. The progressive degeneration of muscle tissues and functions will occur. Most often respiratory, orthopaedic, and cardiac-related complications have led to death. These neuromuscular disorders occur at a frequency of about 1 in 5000 newborn males. The objective of this review was to identify and understand the available measures used for assessing muscular dystrophies in DMD and BMD. Review of studies identified from searching medical bibliographic sources relevant to assessing methods and techniques of DMD and BMD between the years of 2002 and 2022. The studies showed measures used to assess the muscles in DMD patients apart from clinical assessments to quantify the pathological changes involved in the muscles as objective parameters. The measures can be categorized into invasive and non- invasive methods. This study has resulted in manual muscle testing methods and methods of assessing the functional ability of the muscles such as muscle biopsies, Ultrasound scans (USS), and Magnetic Resonance Images (MRI) etc. It concludes that the most widely used effective and reliable investigation method has been identified as MRI scans due to various purposes and methods of assessing muscular dystrophies.

The BELS questionnaire: A novel screening tool for neurodevelopmental and psychiatric symptoms in pediatric dystrophinopathy.

Pediatric patients with dystrophinopathies [Becker and Duchenne muscular dystrophy (BDMD)] are more likely to have neurodevelopmental and neuropsychiatric conditions. This prospective pilot study tested a novel screening questionnaire developed to identify the common behavioral (B), emotional (E), learning (L), and social (S) difficulties in BDMD. A total of 45 caregivers of BDMD patients (ages 4-19 years) seen at the Arkansas Children's Hospital Dystrophinopathy Clinic completed the BELS questionnaire during standard clinic visits. To establish external validity, caregivers also completed four well-validated standardized questionnaires assessing overlapping symptoms [Pediatric Symptom Checklist-17 (PSC-17), Colorado Learning Difficulties Questionnaire (CLDQ), the obsessive compulsive disorder (OCD) subscale from the Revised Children's Anxiety and Depression Scale (RCADS), and Barkley Deficits in Executive Functioning Scale (BDEFS)]. Caregivers reported high rates of behavioral (>60%), emotional (50%-70%), learning (50%-70%), and social (30%-50%) concerns, even though relatively few patients had clinical diagnoses related to these symptoms. Passive suicidality (i.e., thoughts of death) were also common (22.2%; 10/45 patients). The BELS questionnaire was moderately to highly correlated with total scores on the four well-validated questionnaires (p < .001), and BELS subscales showed specificity. A BELS score of 21 corresponded with the established PSC-17 cutoff. The BELS questionnaire shows promise as a screening questionnaire to identify neurobehavioral and neuropsychiatric symptoms common in dystrophinopathy. While BELS cannot currently be used as a standalone measure to make clinical diagnoses, identification of symptoms that warrant further follow-up may improve clinical care and quality of life.

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

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. 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. 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. 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.

FNDC1 is a myokine that promotes myogenesis and muscle regeneration.

Myogenesis is essential for skeletal muscle formation and regeneration after injury, yet its regulators are largely unknown. Here we identified fibronectin type III domain containing 1 (FNDC1) as a previously uncharacterized myokine. In vitro studies showed that knockdown of Fndc1 in myoblasts reduces myotube formation, while overexpression of Fndc1 promotes myogenic differentiation. We further generated recombinant truncated mouse FNDC1 (mFNDC1), which retains reliable activity in promoting myoblast differentiation in vitro. Gain- and loss-of-function studies collectively showed that FNDC1 promotes cardiotoxin (CTX)-induced muscle regeneration in adult mice. Furthermore, recombinant FNDC1 treatment ameliorated pathological muscle phenotypes in the mdx mouse model of Duchenne muscular dystrophy. Mechanistically, FNDC1 bound to the integrin α5β1 and activated the downstream FAK/PI3K/AKT/mTOR pathway to promote myogenic differentiation. Pharmacological inhibition of integrin α5β1 or of the downstream FAK/PI3K/AKT/mTOR pathway abolished the pro-myogenic effect of FNDC1. Collectively, these results suggested that myokine FNDC1 might be used as a therapeutic agent to regulate myogenic differentiation and muscle regeneration for the treatment of acute and chronic muscle disease.

The potential applications of CRISPR/Cas9 in treating Duchenne Muscular Dystrophy

Abstract. The Duchenne Muscular Dystrophy (DMD) is a widespread genetic disorder caused by a mutation in the dystrophin gene. Current treatments, such as corticosteroids and genetic therapies like exon skipping, offer some symptom management but fall short of providing a cure. The CRISPR/Cas9 technology, which is related with Clustered Regularly Interspaced Short Palindromic Repeats-associated protein 9, could edit the genome with great precision. This technique holds potential in tackling the underlying issue of DMD by rectifying mutations in the dystrophin gene. Various strategies, including exon skipping, frame remodeling, and expression regulation, have demonstrated the potential to resumption dystrophin expression and improve muscle fitness in preclinical models. Even with these developments, there are still a number of important obstacles to overcome, such as enhancing the effectiveness of delivery, reducing off-target effects, and managing immune reactions. Future research will focus on refining these techniques and ensuring their safe and effective translation to clinical therapies, potentially revolutionizing the treatment of DMD and other genetic disorders.

Protective effect of maltol on pathological response of cardiomyocyte in dystrophic mice.

Heart diseases are a significant contributor to global morbidity and mortality, and despite their diverse and complex mechanisms, treatment options remain limited. Maltol, a natural compound with antioxidant and anti-inflammatory activities, exhibits potential for addressing this need. This study evaluates the cardioprotective effects of maltol in isoproterenol (ISO)-induced cardiac stress models and Duchenne muscular dystrophy (DMD). Maltol's cardiac cytotoxicity was assessed in rodent (H9c2) and human (AC16) cells and compared with that of dapagliflozin to illustrate its cardiac safety. In ISO-induced stress models, maltol significantly reduced hypertrophic markers and inflammation while enhancing autophagy and antioxidant pathways. In the mdx mice, a DMD model, maltol treatment improved cardiac contractility and reduced pathogenic remodeling. Enhanced phosphorylation of phospholamban and trends toward higher SERCA2a expression indicated enhanced Ca2+ handling, which is crucial in DMD cardiomyopathy. This study demonstrated that maltol has the potential to provide therapeutic benefits for DMD and other cardiac conditions characterized by hypertrophy and inflammation, as evidenced by its well-known antioxidant properties, low cytotoxicity, and capacity to enhance cardiac function and Ca2+ handling.

Evaluation of a six-minute walk test in the DE50-MD canine model of Duchenne muscular dystrophy and its effect on blood-borne biomarkers

Background Duchenne muscular dystrophy (DMD) is a fatal muscle wasting disease caused by mutations in the dystrophin gene resulting in cycles of muscle degeneration, inflammation and regeneration. The 6-minute walk test (6MWT) is a key functional outcome measure for DMD patient clinical trials and has been adapted for use in animal models of the disease. The DE50-MD dog model of DMD closely reflects the DMD patient phenotype prior to loss of ambulation. For pre-clinical trials using this model, functional outcome measures must be established. Methods This longitudinal study compared distance walked in a 6MWT by DE50-MD and WT control dogs and assessed the utility of the 6MWT as a functional biomarker. Dogs underwent two 6MWTs conducted approximately 48-hours apart, at 3, 6, 9, 12, 15 and 18 months of age. In addition, we evaluated the stability of selected blood-borne biomarkers in 12-month old DE50-MD and WT dogs 0, 3, 6, 24 and 48 hours following a 6MWT. Results DE50-MD dogs exhibited significantly shorter 6-minute walk distance (6MWD) than WT dogs at all timepoints (P&lt;0.05), with no difference in 6MWD between the first and second 6MWT. C-C motif chemokine ligand 2 (CCL2), myomesin-3 (MYOM3) and myostatin (MSTN) were biomarkers of the DE50-MD phenotype that remained unchanged in DE50-MD dogs following the 6MWT, while creatine kinase (CK) activity significantly increased 3-hours following the test in DE50-MD dogs but remained unchanged in WT dogs. Conclusions The 6MWT effectively discriminates DE50-MD from WT dogs aged 3-18 months and a single 6MWT is sufficient for future studies. Serum MYOM3, CCL2 and MSTN are good biomarkers of the DE50-MD phenotype that are unaffected by this relatively low level exertion.

Mechanism-based approach in designing patient-specific combination therapies for nonsense mutation diseases.

Premature termination codon (PTC) diseases, arising as a consequence of nonsense mutations in patient DNA, account for approximately 12% of all human disease mutations. Currently there are no FDA approved treatments for increasing PTC readthrough in nonsense mutation diseases, although one translational readthrough inducing drug, ataluren, has had conditional approval for treatment of Duchenne muscular dystrophy in Europe and elsewhere for 10 years. Ataluren displays consistent low toxicity in clinical trials for treatment of several different PTC diseases, but its therapeutic effects on such diseases are inconsistent. The identity of the stop codon and its sequence context are major determinants of PTC readthrough efficiency in both the absence and presence of nonsense suppressors. Previously we have shown that ataluren stimulates readthrough exclusively by competitively inhibiting release factor complex (RFC, eRF1.eRF3.GTP)-dependent catalysis of translation termination. Here, using an in vitro reconstituted system (PURE-LITE) and both ensemble and single molecule assays, we demonstrate that PTC identity and the immediately adjacent mRNA sequence contexts modulate the catalytic activity of RFC in terminating peptide elongation. Such modulation largely determines the effectiveness of ataluren in stimulating readthrough, whether added alone or in combination with either the aminoglycoside G418 or an anticodon edited aa-tRNA, each of which stimulate readthrough by mechanisms orthogonal to that of ataluren. Our results provide an attractive rationale for the variability of ataluren effectiveness in stimulating readthrough in clinical trials. Patients harboring a PTC mutation with a sequence context promoting strong interaction with RFC are predicted to be resistant to ataluren, whereas ataluren treatment should be more effective for patient sequences conferring weaker interaction with RFC.