RESUMEN

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).

Asunto(s)

Distrofia Muscular de Duchenne , Calidad de Vida , Humanos , Estado de Salud , Masculino , Sistema de Registros , Análisis Costo-Beneficio , Niño , Años de Vida Ajustados por Calidad de Vida

RESUMEN

Duchenne muscular dystrophy (DMD) is an X-linked recessive genetic disorder with progressive proximal weakness as the principal sign. Glucocorticoids and physical therapy are the mainstay of treatment. Exercise intolerance is the hallmark of metabolic myopathies, which require a combination of laboratory testing, electrodiagnostic testing, and muscle biopsy for diagnosis. Joint hypermobility may be an isolated finding or be associated with hypermobility Ehlers-Danlos syndrome (EDS), other variants of EDS, or marfanoid syndromes. The latter conditions are associated with aortic and cardiac valvular abnormalities. Osteogenesis imperfecta encompasses a group of disorders characterized by bone fragility presenting with a low-impact fracture as a result of minimal trauma. Management includes multidiscipline specialists. Down syndrome (DS), or trisomy 21, is the most common chromosome abnormality identified in live births. Routine evaluation of atlantoaxial instability with x-ray is no longer recommended for children with DS without symptoms of atlantoaxial instability; however, clinical evaluation of symptoms is required for sports preparticipation. Achondroplasia is the most common skeletal dysplasia. Clinical signs are macrocephaly, short limb, short stature with disproportionately shorter humerus and femur, along with characteristic findings in pelvis and lumbar spine x-rays. Caregivers should be educated on proper positioning and handling to avoid complications, including car seat-related deaths.

Asunto(s)

Acondroplasia , Síndrome de Ehlers-Danlos , Osteogénesis Imperfecta , Humanos , Niño , Síndrome de Ehlers-Danlos/diagnóstico , Síndrome de Ehlers-Danlos/terapia , Adolescente , Acondroplasia/diagnóstico , Acondroplasia/genética , Acondroplasia/terapia , Osteogénesis Imperfecta/diagnóstico , Osteogénesis Imperfecta/terapia , Inestabilidad de la Articulación/diagnóstico , Inestabilidad de la Articulación/terapia , Distrofia Muscular de Duchenne/diagnóstico , Distrofia Muscular de Duchenne/complicaciones , Distrofia Muscular de Duchenne/genética , Distrofia Muscular de Duchenne/terapia , Síndrome de Down/complicaciones , Síndrome de Down/diagnóstico , Enfermedades Musculoesqueléticas/diagnóstico , Enfermedades Musculoesqueléticas/terapia , Síndrome de Marfan/diagnóstico , Síndrome de Marfan/terapia , Síndrome de Marfan/complicaciones , Síndrome de Marfan/genética , Glucocorticoides/uso terapéutico , Modalidades de Fisioterapia

Asunto(s)

Ensayos Clínicos Fase III como Asunto , Hemofilia A , Distrofia Muscular de Duchenne , Humanos , Hemofilia A/terapia , Distrofia Muscular de Duchenne/terapia , Distrofia Muscular de Duchenne/genética , Factor VIII/uso terapéutico , Factor VIII/metabolismo , Factor VIII/genética , Industria Farmacéutica , Terapia Genética/métodos

RESUMEN

The engineered TadA variants used in cytosine base editors (CBEs) present distinctive advantages, including a smaller size and fewer off-target effects compared to cytosine base editors that rely on natural deaminases. However, the current TadA variants demonstrate a preference for base editing in DNA with specific motif sequences and possess dual deaminase activity, acting on both cytosine and adenosine in adjacent positions, limiting their application scope. To address these issues, we employ TadA orthologs screening and multi sequence alignment (MSA)-guided protein engineering techniques to create a highly effective cytosine base editor (aTdCBE) without motif and adenosine deaminase activity limitations. Notably, the delivery of aTdCBE to a humanized mouse model of Duchenne muscular dystrophy (DMD) mice achieves robust exon 55 skipping and restoration of dystrophin expression. Our advancement in engineering TadA ortholog for cytosine editing enriches the base editing toolkits for gene-editing therapy and other potential applications.

Asunto(s)

Adenosina , Citosina , Edición Génica , Distrofia Muscular de Duchenne , Citosina/metabolismo , Animales , Edición Génica/métodos , Adenosina/metabolismo , Ratones , Humanos , Distrofia Muscular de Duchenne/genética , Distrofia Muscular de Duchenne/metabolismo , Ingeniería de Proteínas , Distrofina/genética , Distrofina/metabolismo , Adenosina Desaminasa/metabolismo , Adenosina Desaminasa/genética , Modelos Animales de Enfermedad , Exones/genética , Células HEK293 , Sistemas CRISPR-Cas , Proteínas de Escherichia coli

RESUMEN

BACKGROUND: Deletion or duplication in the DMD gene is one of the most common causes of Duchenne and Becker muscular dystrophy (DMD/BMD). However, the pathogenicity of complex rearrangements involving DMD, especially segmental duplications with unknown breakpoints, is not well understood. This study aimed to evaluate the structure, pattern, and potential impact of rearrangements involving DMD duplication. METHODS: Two families with DMD segmental duplications exhibiting phenotypical differences were recruited. Optical genome mapping (OGM) was used to explore the cryptic pattern of the rearrangements. Breakpoints were validated using long-range polymerase chain reaction combined with next-generation sequencing and Sanger sequencing. RESULTS: A multi-copy duplication involving exons 64-79 of DMD was identified in Family A without obvious clinical symptoms. Family B exhibited typical DMD neuromuscular manifestations and presented a duplication involving exons 10-13 of DMD. The rearrangement in Family A involved complex in-cis tandem repeats shown by OGM but retained a complete copy (reading frame) of DMD inferred from breakpoint validation. A reversed insertion with a segmental repeat was identified in Family B by OGM, which was predicted to disrupt the normal structure and reading frame of DMD after confirming the breakpoints. CONCLUSIONS: Validating breakpoint and rearrangement pattern is crucial for the functional annotation and pathogenic classification of genomic structural variations. OGM provides valuable insights into etiological analysis of DMD/BMD and enhances our understanding for cryptic effects of complex rearrangements.

Asunto(s)

Distrofina , Exones , Distrofia Muscular de Duchenne , Linaje , Fenotipo , Humanos , Distrofia Muscular de Duchenne/genética , Distrofia Muscular de Duchenne/patología , Distrofina/genética , Masculino , Exones/genética , Femenino , Mapeo Cromosómico , Reordenamiento Génico/genética , Niño , Duplicaciones Segmentarias en el Genoma/genética , Secuenciación de Nucleótidos de Alto Rendimiento , Duplicación de Gen/genética , Adolescente

RESUMEN

Duchenne Muscular dystrophy (DMD), a yet-incurable X-linked recessive disorder that results in muscle wasting and loss of ambulation is due to mutations in the dystrophin gene. Exonic duplications of dystrophin gene are a common type of mutations found in DMD patients. In this study, we utilized a single guide RNA CRISPR strategy targeting intronic regions to delete the extra duplicated regions in patient myogenic cells carrying duplication of exon 2, exons 2-9, and exons 8-9 in the DMD gene. Immunostaining on CRISPR-corrected derived myotubes demonstrated the rescue of dystrophin protein. Subsequent RNA sequencing of the DMD cells indicated rescue of genes of dystrophin related pathways. Examination of predicted close-match off-targets evidenced no aberrant gene editing at these loci. Here, we further demonstrate the efficiency of a single guide CRISPR strategy capable of deleting multi-exon duplications in the DMD gene without significant off target effect. Our study contributes valuable insights into the safety and efficacy of using single guide CRISPR strategy as a potential therapeutic approach for DMD patients with duplications of variable size.

Asunto(s)

Sistemas CRISPR-Cas , Distrofina , Exones , Duplicación de Gen , Edición Génica , Distrofia Muscular de Duchenne , Distrofia Muscular de Duchenne/genética , Distrofia Muscular de Duchenne/terapia , Humanos , Exones/genética , Distrofina/genética , Edición Génica/métodos , ARN Guía de Sistemas CRISPR-Cas/genética , Terapia Genética/métodos , Fibras Musculares Esqueléticas/metabolismo

RESUMEN

BACKGROUND: Duchenne Muscular Dystrophy (DMD) is an X-linked disorder caused by mutations in the DMD gene, with large deletions being the most common type of mutation. Inversions involving the DMD gene are a less frequent cause of the disorder, largely because they often evade detection by standard diagnostic methods such as multiplex ligation probe amplification (MLPA) and whole exome sequencing (WES). CASE PRESENTATION: Our research identified two intrachromosomal inversions involving the dystrophin gene in two unrelated families through Long-read sequencing (LRS). These variants were subsequently confirmed via Sanger sequencing. The first case involved a pericentric inversion extending from DMD intron 47 to Xq27.3. The second case featured a paracentric inversion between DMD intron 42 and Xp21.1, inherited from the mother. In both cases, simple repeat sequences (SRS) were present at the breakpoints of these inversions. CONCLUSIONS: Our findings demonstrate that LRS is an effective tool for detecting atypical mutations. The identification of SRS at the breakpoints in DMD patients enhances our understanding of the mechanisms underlying structural variations, thereby facilitating the exploration of potential treatments.

Asunto(s)

Inversión Cromosómica , Distrofina , Distrofia Muscular de Duchenne , Humanos , Distrofina/genética , Distrofia Muscular de Duchenne/genética , Masculino , Inversión Cromosómica/genética , Puntos de Rotura del Cromosoma , Femenino , Linaje , Niño , Análisis de Secuencia de ADN

RESUMEN

Background: Duchenne muscular dystrophy (DMD) is a progressive, life-limiting, neuromuscular disorder. Clinicians play an important role in informing families about therapy options, including approved gene therapies and clinical trials of unapproved therapies. Objective: This study aimed to understand the perspectives of clinicians about gene therapy for DMD, which has not previously been studied. Methods: We conducted interviews with specialist clinicians treating patients with DMD in the United States (n = 8) and United Kingdom (n = 8). Interviews were completed in 2022, before any approved gene therapies, to gain insight into barriers and facilitators to implementing gene therapy and educational needs of clinicians. Results: Most respondents expressed cautious optimism about gene therapy. Responses varied regarding potential benefits with most expecting delayed progression and duration of benefit (1 year to lifelong). Concern about anticipated risks also varied; types of anticipated risks included immunological reactions, liver toxicity, and cardiac or renal dysfunction. Clinicians generally, but not uniformly, understood that gene therapy for DMD would not be curative. Most reported needing demonstrable clinical benefit to justify treatment-related risks. Conclusions: Our data demonstrate variability in knowledge and attitudes about gene therapy among clinicians who follow patients with DMD. As our knowledge base about DMD gene therapy grows, clinician education is vital to ensuring that accurate information is communicated to patients and families.

Asunto(s)

Terapia Genética , Distrofia Muscular de Duchenne , Distrofia Muscular de Duchenne/terapia , Distrofia Muscular de Duchenne/genética , Humanos , Terapia Genética/métodos , Actitud del Personal de Salud , Estados Unidos , Reino Unido , Masculino , Femenino

RESUMEN

BACKGROUND: An increasing number of clinical trials for new therapeutic strategies are underway or being considered for dystrophinopathy. Having detailed data on the natural progression of this condition is crucial for assessing the effectiveness of new drugs. However, there's a lack of data regarding the long-term data on the natural course and how it's managed in China. In this study, we offer a comprehensive overview of clinical and molecular findings, as well as treatment outcomes in the Chinese population. METHODS: Institutional data on all patients with dystrophinopathy from August 2011 to August 2021 were retrospectively reviewed. The data included geographic distribution, age at diagnosis, molecular findings, and treatment options, such as corticosteroids, cardiac interventions, and clinical outcomes. RESULTS: In total, 2097 patients with dystrophinopathy, including 1703 cases of Duchenne muscular dystrophy (DMD), 311 cases of Becker muscular dystrophy (BMD), 46 cases of intermediate muscular dystrophy (IMD), and 37 cases categorized as "pending" (individuals with an undetermined phenotype), were registered in the Children's Hospital of Fudan University database for dystrophinopathy from August 2011 to August 2021. The spectrum of identified variants included exonic deletions (66.6%), exonic duplications (10.7%), nonsense variants (10.3%), splice-site variants (4.5%), small deletions (3.5%), small insertions/duplications (1.8%), and missense variants (0.9%). Four deep intronic variants and two inversion variants were identified. Regarding treatment, glucocorticoids were administered to 54.4% of DMD patients and 39.1% of IMD patients. The median age at loss of ambulation was 2.5 years later in DMD patients who received glucocorticoid treatment. Overall, one cardiac medicine at least was prescribed to 7.4% of DMD patients, 8.3% of IMD patients, and 2.6% of BMD patients. Additionally, ventilator support was required by four DMD patients. Eligibility for exon skipping therapy was found in 55.3% of DMD patients, with 12.9%, 10%, and 9.6% of these patients being eligible for skipping exons 51, 53, and 45, respectively. CONCLUSIONS: This is one of the largest studies to have evaluated the natural history of dystrophinopathy in China, which is particularly conducive to the recruitment of eligible patients for clinical trials and the provision of real-world data to support drug development.

Asunto(s)

Distrofia Muscular de Duchenne , Humanos , Distrofia Muscular de Duchenne/genética , Distrofia Muscular de Duchenne/tratamiento farmacológico , Masculino , Estudios Retrospectivos , Niño , Femenino , Preescolar , Adolescente , Distrofina/genética , China , Bases de Datos Factuales , Lactante , Distrofias Musculares/genética , Distrofias Musculares/tratamiento farmacológico , Adulto Joven

Asunto(s)

Distrofina , Terapia Genética , Vectores Genéticos , Distrofia Muscular de Duchenne , Distrofia Muscular de Duchenne/terapia , Distrofia Muscular de Duchenne/genética , Distrofina/genética , Terapia Genética/métodos , Humanos , Vectores Genéticos/genética , Vectores Genéticos/administración & dosificación , Animales , Modelos Animales de Enfermedad

RESUMEN

Caveolin is a structural protein within caveolae that may be involved in transmembrane molecular transport and/or various intercellular interactions within cells. Specific mutations of caveolin-3 in muscle fibers are well known to cause limb-girdle muscular dystrophy. Altered expression of caveolin-3 has also been detected in Duchenne muscular dystrophy, which may be a part of the pathological process leading to muscle weakness. Interestingly, it has been shown that the renovation of nitric oxide synthase (NOS) in sarcolemma with muscular dystrophy could improve muscle health, suggesting that NOS may be involved in the pathology of muscular dystrophy. Here, we summarize the notable function of caveolin and/or NOS in skeletal muscle fibers and discuss their involvement in the pathology as well as possible tactics for the innovative treatment of muscular dystrophies.

Asunto(s)

Caveolina 3 , Distrofias Musculares , Óxido Nítrico Sintasa , Animales , Humanos , Caveolas/metabolismo , Caveolina 3/metabolismo , Caveolina 3/genética , Caveolinas/metabolismo , Distrofias Musculares/metabolismo , Distrofias Musculares/genética , Distrofias Musculares/patología , Distrofia Muscular de Duchenne/metabolismo , Distrofia Muscular de Duchenne/genética , Distrofia Muscular de Duchenne/patología , Mutación , Óxido Nítrico Sintasa/metabolismo , Óxido Nítrico Sintasa/genética

Asunto(s)

Distrofia Muscular de Duchenne , Distrofia Muscular de Duchenne/genética , Distrofia Muscular de Duchenne/tratamiento farmacológico , Humanos , Accesibilidad a los Servicios de Salud , Terapia Genética

RESUMEN

Antibody-oligonucleotide conjugates (AOCs) are promising treatments for Duchenne muscular dystrophy (DMD). They work via induction of exon skipping and restoration of dystrophin protein in skeletal and heart muscles. The structure-activity relationships (SARs) of AOCs comprising antibody-phosphorodiamidate morpholino oligomers (PMOs) depend on several aspects of their component parts. We evaluate the SAR of antimouse transferrin receptor 1 antibody (αmTfR1)-PMO conjugates: cleavable and noncleavable linkers, linker location on the PMO, and the impact of drug-to-antibody ratios (DARs) on plasma pharmacokinetics (PK), oligonucleotide delivery to tissues, and exon skipping. AOCs containing a stable linker with a DAR9.7 were the most effective PMO delivery vehicles in preclinical studies. We demonstrate that αmTfR1-PMO conjugates induce dystrophin protein restoration in the skeletal and heart muscles of mdx mice. Our results show that αmTfR1-PMO conjugates are a potentially effective approach for the treatment of DMD.

Asunto(s)

Ratones Endogámicos mdx , Morfolinos , Distrofia Muscular de Duchenne , Animales , Morfolinos/química , Morfolinos/farmacología , Morfolinos/farmacocinética , Relación Estructura-Actividad , Ratones , Distrofia Muscular de Duchenne/tratamiento farmacológico , Desarrollo de Medicamentos , Distrofina/metabolismo , Distrofina/genética , Inmunoconjugados/química , Inmunoconjugados/farmacología , Inmunoconjugados/farmacocinética , Humanos , Masculino , Ratones Endogámicos C57BL , Oligonucleótidos/química , Oligonucleótidos/farmacocinética , Músculo Esquelético/metabolismo , Receptores de Transferrina/metabolismo , Receptores de Transferrina/inmunología

RESUMEN

Structural variants (SVs) of unknown significance are great challenges for prenatal risk assessment, especially when involving dose-sensitive genes such as DMD The pathogenicities of 5'-terminal DMD duplications in the database remain controversial. Four prenatal cases with Xp21.1 duplications were identified by routine prenatal genomic testing, encompassing the 5'-UTR to exons 1-2 in family 1 and family 2, and to exons 1-9 in family 3. The duplication in family 4 was non-contiguous covering the 5'-UTR to exon 1 and exons 3-7. All were traced to unaffected males in the family pedigrees. A new genome-wide approach of optical genome mapping was performed in families 1, 2, and 3 to delineate the breakpoints and orientation of the duplicated fragments. The extra copies were tandemly inserted into the upstream of DMD, preserving the integrity of ORF from the second copy. The pathogenicities were thus reclassified as likely benign. Our data highlight the importance of structural delineation by optical genome mapping in prenatal risk assessment of incidentally identified SVs involving DMD and other similar large dose-sensitive genes.

Asunto(s)

Distrofina , Linaje , Humanos , Femenino , Masculino , Medición de Riesgo/métodos , Embarazo , Distrofina/genética , Diagnóstico Prenatal/métodos , Mapeo Cromosómico/métodos , Cromosomas Humanos X/genética , Distrofia Muscular de Duchenne/genética , Distrofia Muscular de Duchenne/diagnóstico , Duplicación Cromosómica/genética , Exones/genética , Duplicación de Gen/genética , Adulto

RESUMEN

BACKGROUND AND AIMS: Although aerobic exercises such as cycling and swimming are increasingly being recommended in Duchenne muscular dystrophy (DMD), their effect on gait and balance parameters is unclear. This study was aimed to investigate the effect of cycling training on balance and spatio-temporal gait parameters in children with DMD. METHODS: Ambulant children (age range: 6.17-11.33 years) were randomly divided into two groups: home-based exercise training applied in the control group (n = 12) while 12 weeks of supervised submaximal lower extremity cycling training in addition to home-based exercise training performed in the study group (n = 11). Gait and balance parameters were evaluated using the GAITRite electronic walkway system and the Bertec Balance Check Screener™, respectively. Assessments were applied before and after 12 weeks of training. RESULTS: The mean ages of the children in the study and control groups were 8.20 (SD:1.34) and 8.86 (SD:1.30) years, consecutively (p > 0.05). Considering the baseline values, the balance and spatio-temporal gait parameters of the children were similar except for the antero-posterior postural sway on the perturbed surface with eyes open (p > 0.05). There was a significant time x group interaction effect in favor of the study group for the antero-posterior postural sway of children on the normal surface with eyes open (F (1,58) = 12.62, p = 0.002). It was found that the antero-posterior postural sway on the normal surface with eyes open was improved in the study group within group comparison (F (1,10) = 8.50, p = 0.015). CONCLUSIONS: The study showed that both the cycling and the home-based exercise training groups may maintain gait and balance parameters during the study. Adding a cycling training to the rehabilitation program can also provide additional contribution to improve antero-posterior balance.

Asunto(s)

Terapia por Ejercicio , Marcha , Distrofia Muscular de Duchenne , Equilibrio Postural , Humanos , Distrofia Muscular de Duchenne/rehabilitación , Distrofia Muscular de Duchenne/fisiopatología , Niño , Equilibrio Postural/fisiología , Masculino , Terapia por Ejercicio/métodos , Marcha/fisiología , Femenino , Ciclismo/fisiología , Resultado del Tratamiento

RESUMEN

PURPOSE: The aim of this study was to examine the cognitive and emotional-behavioural outcomes of Turkish children with Duchenne muscular dystrophy (DMD) in comparison with healthy peers, to determine its relationship with motor functions, and to analyse the difference of cognitive and emotional-behavioural outcomes according to the site of mutations. METHOD: Children aged 7-16 years with DMD (n = 68) and age-matched typically developing children (n = 33) were included in the study. The cognitive and emotional-behavioural status and the motor functions were assessed in detail. Children with DMD also divided into two groups as "proximal" and "distal" site mutation groups to compare the cognitive and emotional-behavioural outcomes. RESULTS: The children with DMD and typically developing children were similar in terms of age and body mass index (p > 0.05). Significant differences were found between children with DMD and typically developing peers in almost all subtests of both cognitive and emotional-behavioural assessments (p < 0.05). Cognitive and emotional-behavioural parameters were weakly correlated with specific motor parameters responsive to cognitive functioning (p < 0.05). Children with distal site mutation performed significantly worser than those with proximal site mutation in particular cognitive subtest (p < 0.05). CONCLUSIONS: It is concluded that comprehensive and detailed evaluation of cognitive and emotional-behavioural features of children with DMD is essential for better implementation of rehabilitation programs to maintain motor function which especially requires cognitive ability, since a Turkish cohort represented challenges in particular domains of cognitive and emotional-behavioural areas. CLINICAL TRIAL REGISTRATION NUMBER: NCT05661071.

Asunto(s)

Distrofia Muscular de Duchenne , Humanos , Distrofia Muscular de Duchenne/psicología , Distrofia Muscular de Duchenne/fisiopatología , Niño , Masculino , Adolescente , Turquía/epidemiología , Femenino , Emociones/fisiología , Cognición/fisiología , Pruebas Neuropsicológicas , Mutación

RESUMEN

Duchenne muscular dystrophy (DMD) is an X-linked progressive muscle degenerative disease, caused by mutations in the dystrophin gene and resulting in premature death. As a major secondary event, an abnormal elevation of the intracellular calcium concentration in the dystrophin-deficient muscle contributes to disease progression in DMD. In this study, we investigated the specific functional features of induced pluripotent stem cell-derived muscle cells (hiPSC-skMCs) generated from DMD patients to regulate intracellular calcium concentration. As compared to healthy hiPSC-skMCs, DMD hiPSC-skMCs displayed specific spontaneous calcium signatures with high levels of intracellular calcium concentration. Furthermore, stimulations with electrical field or with acetylcholine perfusion induced higher calcium response in DMD hiPSC-skMCs as compared to healthy cells. Finally, Mn2+ quenching experiments demonstrated high levels of constitutive calcium entries in DMD hiPSC-skMCs as compared to healthy cells. Our findings converge on the fact that DMD hiPSC-skMCs display intracellular calcium dysregulation as demonstrated in several other models. Observed calcium disorders associated with RNAseq analysis on these DMD cells highlighted some mechanisms, such as spontaneous and activated sarcoplasmic reticulum (SR) releases or constitutive calcium entries, known to be disturbed in other dystrophin-deficient models. However, store operated calcium entries (SOCEs) were not found to be dysregulated in our DMD hiPSC-skMCs model. These results suggest that all the mechanisms of calcium impairment observed in other animal models may not be as pronounced in humans and could point to a preference for certain mechanisms that could correspond to major molecular targets for DMD therapies.

Asunto(s)

Calcio , Células Madre Pluripotentes Inducidas , Distrofia Muscular de Duchenne , Distrofia Muscular de Duchenne/metabolismo , Distrofia Muscular de Duchenne/patología , Células Madre Pluripotentes Inducidas/metabolismo , Células Madre Pluripotentes Inducidas/patología , Humanos , Calcio/metabolismo , Señalización del Calcio , Fibras Musculares Esqueléticas/metabolismo , Fibras Musculares Esqueléticas/patología , Diferenciación Celular , Células Cultivadas , Músculo Esquelético/metabolismo , Músculo Esquelético/patología , Retículo Sarcoplasmático/metabolismo

RESUMEN

Duchenne muscular dystrophy (DMD) is a progressive muscle wasting disorder affecting 1:3500 male births and is associated with myofiber degeneration, regeneration, and inflammation. Glucocorticoid treatments have been the standard of care due to immunomodulatory/immunosuppressive properties but novel genetic approaches, including exon skipping and gene replacement therapy, are currently being developed. The identification of additional biomarkers to assess DMD-related inflammatory responses and the potential efficacy of these therapeutic approaches are thus of critical importance. The current study uses RNA sequencing of skeletal muscle from two mdx mouse models to identify high mobility group box 1 (HMGB1) as a candidate biomarker potentially contributing to DMD-related inflammation. HMGB1 protein content was increased in a human iPSC-derived skeletal myocyte model of DMD and microdystrophin treatment decreased HMGB1 back to control levels. In vivo, HMGB1 protein levels were increased in vehicle treated B10-mdx skeletal muscle compared to B10-WT and significantly decreased in B10-mdx animals treated with adeno-associated virus (AAV)-microdystrophin. However, HMGB1 protein levels were not increased in D2-mdx skeletal muscle compared to D2-WT, demonstrating a strain-specific difference in DMD-related immunopathology.

Asunto(s)

Biomarcadores , Proteína HMGB1 , Distrofia Muscular de Duchenne , Animales , Humanos , Masculino , Ratones , Modelos Animales de Enfermedad , Distrofina/metabolismo , Distrofina/genética , Proteína HMGB1/metabolismo , Proteína HMGB1/genética , Células Madre Pluripotentes Inducidas/metabolismo , Ratones Endogámicos mdx , Músculo Esquelético/metabolismo , Distrofia Muscular de Duchenne/metabolismo , Distrofia Muscular de Duchenne/genética

RESUMEN

Dystrophinopathies are a group of neuromuscular disorders, inherited in an X-linked recessive manner, caused by pathogenic variants in the DMD gene. Copy number variation detection and next generation sequencing allow the detection of around 99 % of the pathogenic variants. However, some patients require mRNA studies from muscle biopsies to identify deep intronic pathogenic variants. Here, we report a child suspected of having Duchenne muscular dystrophy, with a muscle biopsy showing dystrophin deficiency, and negative molecular testing for deletions, duplications, and small variants. mRNA analysis from muscle biopsy revealed a pseudoexon activation that introduce a premature stop codon into the reading frame. gDNA sequencing allowed to identified a novel variant, c.832-186 T>G, which creates a cryptic donor splice site, recognizing the underlying mechanism causing the pseudoexon insertion. This case highlights the usefulness of the mRNA analysis from muscle biopsy when routine genetic testing is negative and clinical suspicion of dystrophinopathies remains the main clinical diagnosis suspicion.

Asunto(s)

Codón sin Sentido , Distrofina , Intrones , Distrofia Muscular de Duchenne , Humanos , Distrofia Muscular de Duchenne/genética , Distrofina/genética , Masculino , Exones , Niño , ARN Mensajero/genética , ARN Mensajero/metabolismo

RESUMEN

BACKGROUND: Hand dexterity is important with Duchenne muscular dystrophy (DMD). OBJECTIVE: The aim of this study was to compare hand dexterity and hand laterality task assessments in patients with DMD with typically-developing peers. METHODS: The study included 25 DMD with a mean age of 10.2±2.38 and 21 typically-developing peers with a mean age of 10.33±2.26. Functional levels of DMD patients were determined by Brooke Upper Extremity Functional Classification Scale and Brooke Lower Extremity Functional Scale. The ABILHAND-Kids and 9-hole peg test were used to assess the hand dexterity of all participants, and assess the hand laterality task. RESULTS: Patients with DMD had lower ABILHAND-Kids scores than their typically-developing peers (p < 0.001). Patients with DMD had higher 9-hole peg test duration on the dominant and non-dominant extremity compared to typically-developing peers (p < 0.001). Patients with DMD were found to be different from their typically-developing peers (p < 0.001) in lateralization response time and accuracy. CONCLUSION: Patients with DMD were found to have lower manual dexterity and hand laterality task skills compared to their typically-developing peers. It is recommended that hand dexterity and upper extremity recognition capacities should be considered in assessment and intervention programs for physiotherapists and clinicians working in this field.

Asunto(s)

Lateralidad Funcional , Mano , Distrofia Muscular de Duchenne , Humanos , Distrofia Muscular de Duchenne/fisiopatología , Lateralidad Funcional/fisiología , Masculino , Niño , Mano/fisiopatología , Adolescente , Femenino , Destreza Motora/fisiología