Becker Muscular Dystrophy Research Articles

Caregiver Burden with Duchenne and Becker Muscular Dystrophy in Japan: A Clinical Observation Study.

Objective Skeletal muscle weakness and cardiomyopathy can be seen in carriers of dystrophinopathy. Therefore, the health management of caregivers of Duchenne/Becker muscular dystrophy (DMD/BMD) patients who are themselves carriers is an important issue. However, few studies have focused on caregivers who have dystrophin mutations. Methods In this cross-sectional study conducted at five hospitals, the daily living, situation medical treatment status, genetic testing, physical assessment, care burden, and quality of life of caregivers of DMD/BMD patients were surveyed. Results The subjects were 36 main caregivers (mean age 55.7±8.4 years old), of whom 52.8% were diagnosed as carriers, 8.3% were noncarriers, and 38.9% were not confirmed. In addition, half of the caregivers were not examined regularly at medical institutions. Of all caregivers, 54.3% had muscle or cardiac symptoms, and 75% had elevated serum creatine kinase levels. The mean Zarit Caregiver Burden Interview (ZBI) total score of current caregivers was 20.9±13.1. The frequency of a ZBI total score ≥25 was significantly higher in caregivers diagnosed as carriers than in caregivers unexamined as carriers (p=0.04). The health-related quality of life score (Short Form 36; SF-36) in caregivers was slightly lower than the Japanese standard scores in the sections of physical functioning, role limitations-physical, bodily pain, and social functioning. Conclusion Some caregivers of DMD/BMD patients can themselves have muscular or cardiac symptoms and a heavy care burden. It is therefore necessary for carrier caregivers, especially women, to undergo regular health checkups and receive appropriate health management.

Evolution of neuropsychological and behavioral profile in a cohort of pediatric patients with Becker muscular dystrophy in a longitudinal study

It has long been reported that neuropsychological deficits may be present in dystrophinopathies, specifically non-progressive cognitive impairment and a global deficit in executive functions; this neurocognitive profile has been less explored in patients with Becker than Duchenne muscular dystrophy (BMD/DMD). We conducted a longitudinal study to explore the evolution of neuropsychological and behavioural profile in a cohort of paediatric BMD. Seventeen patients with BMD without intellectual disability were assessed using a full battery of tests, including intellectual, adaptive and executive functioning, language and behavioral features. Tests were performed at baseline and after 12 months. The results showed adequate cognitive and adaptive profile with falls in Working Memory, as well as lower scores in executive functions. An improvement was observed in Processing Speed. Behavioral questionnaires confirmed a negative trend, while in normal ranges. We found a statistically significant difference between T0 and T1 in some items exploring executive functions. No statistically significant difference was observed stratifying patients by mutation site or IQ level. In conclusion, our study suggests that BMD patients have a stable neurocognitive profile, while a deflection in the executive functions may be observed. We recommend a careful monitoring to intercept learning disabilities and promptly start a multimodal rehabilitation.

Diverse Cardiac Phenotype of Becker Muscular Dystrophy: Under-Recognized Subclinical Cardiomyopathy Due to Partial Dystrophin Deficiency in a Contemporary Era.

Becker muscular dystrophy (BMD) is an X-linked recessive disorder responsible for mild skeletal muscle involvement and variable degree of cardiomyopathy. The characteristics of cardiac phenotype of BMD in childhood remain elusive. Clinical manifestations, genotype, serum biomarkers, and echocardiogram were retrospectively reviewed in BMD patients. Cardiac phenotype was classified into acute progressive (AP), chronic persistent (CP), and latent (L) groups based upon symptoms and echocardiographic findings. Twenty-five BMD patients were studied over 9.5 ± 2.5years. Sixteen patients presented initially with variable degree of muscle weakness whereas 9 were asymptomatic. Three patients developed medically refractory heart failure by age 18 with progressive dilated cardiomyopathy (DCM) (AP). Six patients developed mild to moderate left ventricular (LV) systolic dysfunction with LV dilatation but remained asymptomatic (CP). Although 16 patients continued to show normal LV function (L), they demonstrated variable degrees of skeletal muscle involvement. The AP groups presented with significantly larger LV size and LV mass index (LVMI) at the initial encounter than groups CP or L, suggesting early myocardial remodeling predicts rapid disease progression. None presented with atrophic myocardial phenotype commonly observed in Duchenne muscular dystrophy (DMD). Wide availability of genetic testing has changed the scope of clinical presentation of BMD. Cardiomyopathy in BMD presents with a diverse clinical spectrum with variable progression of DCM where larger LV dimension and mass at the time of diagnosis may predict the progressiveness of cardiomyopathy.

Duchenne and Becker muscular dystrophy: Cellular mechanisms, image analysis, and computational models: A review.

The muscle is the principal tissue that is capable to transform potential energy into kinetic energy. This process is due to the transformation of chemical energy into mechanical energy to enhance the movements and all the daily activities. However, muscular tissues can be affected by some pathologies associated with genetic alterations that affect the expression of proteins. As the muscle is a highly organized structure in which most of the signaling pathways and proteins are related to one another, pathologies may overlap. Duchenne muscular dystrophy (DMD) is one of the most severe muscle pathologies triggering degeneration and muscle necrosis. Several mathematical models have been developed to predict muscle response to different scenarios and pathologies. The aim of this review is to describe DMD and Becker muscular dystrophy in terms of cellular behavior and molecular disorders and to present an overview of the computational models implemented to understand muscle behavior with the aim of improving regenerative therapy.

Title-molecular diagnostics of dystrophinopathies in Sri Lanka towards phenotype predictions: an insight from a South Asian resource limited setting

BackgroundThe phenotype of Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD) patients is determined by the type of DMD gene variation, its location, effect on reading frame, and its size. The primary objective of this investigation was to determine the frequency and distribution of DMD gene variants (deletions/duplications) in Sri Lanka through the utilization of a combined approach involving multiplex polymerase chain reaction (mPCR) followed by Multiplex Ligation Dependent Probe Amplification (MLPA) and compare to the international literature. The current consensus is that MLPA is a labor efficient yet expensive technique for identifying deletions and duplications in the DMD gene.MethodologyGenetic analysis was performed in a cohort of 236 clinically suspected pediatric and adult myopathy patients in Sri Lanka, using mPCR and MLPA. A comparative analysis was conducted between our findings and literature data.ResultsIn the entire patient cohort (n = 236), mPCR solely was able to identify deletions in the DMD gene in 131/236 patients (DMD-120, BMD-11). In the same cohort, MLPA confirmed deletions in 149/236 patients [DMD-138, BMD -11]. These findings suggest that mPCR has a detection rate of 95% (131/138) among all patients who received a diagnosis. The distal and proximal deletion hotspots for DMD were exons 45–55 and 6–15. Exon 45–60 identified as a novel in-frame variation hotspot. Exon 45–59 was a hotspot for BMD deletions. Comparisons with the international literature show significant variations observed in deletion and duplication frequencies in DMD gene across different populations.ConclusionDMD gene deletions and duplications are concentrated in exons 45–55 and 2–20 respectively, which match global variation hotspots. Disparities in deletion and duplication frequencies were observed when comparing our data to other Asian and Western populations. Identified a 95% deletion detection rate for mPCR, making it a viable initial molecular diagnostic approach for low-resource countries where MLPA could be used to evaluate negative mPCR cases and cases with ambiguous mutation borders. Our findings may have important implications in the early identification of DMD with limited resources in Sri Lanka and to develop tailored molecular diagnostic algorithms that are regional and population specific and easily implemented in resource limited settings.

Findings from the Longitudinal CINRG Becker Natural History Study.

Becker muscular dystrophy is an X-linked, genetic disorder causing progressive degeneration of skeletal and cardiac muscle, with a widely variable phenotype. A 3-year, longitudinal, prospective dataset contributed by patients with confirmed Becker muscular dystrophy was analyzed to characterize the natural history of this disorder. A better understanding of the natural history is crucial to rigorous therapeutic trials. A cohort of 83 patients with Becker muscular dystrophy (5-75 years at baseline) were followed for up to 3 years with annual assessments. Muscle and pulmonary function outcomes were analyzed herein. Age-stratified statistical analysis and modeling were conducted to analyze cross-sectional data, time-to-event data, and longitudinal data to characterize these clinical outcomes. Deletion mutations of dystrophin exons 45-47 or 45-48 were most common. Subgroup analysis showed greater pairwise association between motor outcomes at baseline than association between these outcomes and age. Stronger correlations between outcomes for adults than for those under 18 years were also observed. Using cross-sectional binning analysis, a ceiling effect was seen for North Star Ambulatory Assessment but not for other functional outcomes. Longitudinal analysis showed a decline in percentage predicted forced vital capacity over the life span. There was relative stability or improved median function for motor functional outcomes through childhood and adolescence and decreasing function with age thereafter. There is variable progression of outcomes resulting in significant heterogeneity of the clinical phenotype of Becker muscular dystrophy. Disease progression is largely manifest in adulthood. There are implications for clinical trial design revealed by this longitudinal analysis of a Becker natural history dataset.

Empowerment of genetic information by women at-risk of being carriers of Duchenne and Becker muscular dystrophies.

The emergence of therapies acting on specific molecular targets for Duchenne and Becker muscular dystrophies (DBMD) led to expanded access of diagnostic DMD analysis. However, it is unclear how much of these advances have also improved healthcare and access to genetic testing for women at-risk of being carriers. This study evaluates the process of genetic counseling and empowerment of genetic information by women from DBMD families. We carried out a cross-sectional study between February and June 2022 in Brazil. The online survey with items regarding sociodemographic data; family history; access to health services; reproductive decisions; and the Genomic Outcome Scale was answered by 123 women recruited from a rare diseases reference service and a nationwide patient advocacy group. Genetic counseling was reported by 77/123 (62.6%) of women and 53.7% reported having performed genetic analysis of DMD. Although the majority knew about the risks for carriers of developing heart disease and muscle weakness, only 35% of potential carriers have had cardiac studies performed at least once in their lives. Country region, type of kinship, number of affected males in the family, age, notion of genetic risk, education level, and participation in advocacy groups were the main factors associated with adequate healthcare access to women and empowerment of genetic information. Education to health professionals and policies to expand access to carrier genetic testing, whether public policies or regulation of pharmaceutical companies' diagnostic programs, is paramount to improve the care of families with DBMD in Brazil.

Role of Ayurveda in the Management of Becker Muscular Dystrophy: A Case Study

Abstract Muscular dystrophies are a group of genetic disorders that lead to a gradual weakening of muscles, resulting in increased disability over time. Becker muscular dystrophy (BMD) is one such condition and is inherited through an X-linked recessive pattern, primarily affecting males. Symptoms of BMD typically begin in the teenage years or late twenties. Initial signs may include muscle cramps during exercise and reduced stamina. Over time, there is a gradual loss of muscle bulk in the hips, pelvis, thighs, and shoulders, often leading to a tendency to walk on toes. In Ayurveda, the factors contributing to this disease are believed to be an aggravation of Vata (one of the three doshas), depletion of Mamsa (muscle tissue), and Meda (fat tissue), impaired digestive fire, and blockage of functional channels (Srotorodha). The present case involved a 15-year-old male with weakness in both lower limbs for 4 years, a decrease in muscle mass around the pelvic and thigh area for 3 years, and an increase in calf muscle size for 3 years. The patient exhibited pseudohypertrophy in both calf muscles and positive Gower’s sign, along with a positive family history and elevated creatine phosphokinase levels, leading to a diagnosis of BMD. The treatment approach incorporated Panchakarma therapies and internal Ayurvedic formulations in line with the management of Sarvang Vata disorder. The treatment was administered in four sessions, with a 3-month gap between each therapy session. After a year of treatment, there was not only a halt in the progression of the disease but also a notable improvement in lower limb strength, which increased from 4 to 4+. In addition, there was an increase in proximal muscle mass, from 12.5 inches to 13 inches, and a reduction in calf muscle size and tightness. This promising outcome suggests the potential for managing the disease using Ayurvedic principles and therapies.

Identification and characterization of dystrophin-locus-derived testis-specific protein: A testis-specific gene within the intronic region of the rat dystrophin gene.

The mammalian X chromosome exhibits enrichment in genes associated with germ cell development. Previously, we generated a rat model of Becker muscular dystrophy (BMD) characterized by an in-frame mutation in the dystrophin gene, situated on the X chromosome and responsible for encoding a protein crucial for muscle integrity. Male BMD rats are infertile owing to the absence of normal spermatids in the epididymis. Within the seminiferous tubules of BMD rats, elongated spermatids displayed abnormal morphology. To elucidate the cause of infertility, we identified a putative gene containing an open reading frame situated in the intronic region between exons 6 and 7 of the dystrophin gene, specifically deleted in male BMD rats. This identified gene, along with its encoded protein, exhibited specific detection within the testes, exclusively localized in round to elongated spermatids during spermiogenesis. Consequently, we designated the encoded protein as dystrophin-locus-derived testis-specific protein (DTSP). Given the absence of DTSP in the testes of BMD rats, we hypothesized that the loss of DTSP contributes to the infertility observed in male BMD rats.

Social cognition in two brothers with Becker muscular dystrophy: an exploratory study revealing divergent behavioral phenotypes.

Only few studies investigated social cognition in Becker muscular dystrophy (BMD). However, brain dystrophin deficiency could be a neural substrate for cognitive, emotional, and neuropsychological features in BMD. We compared interoceptive accuracy and interpersonal comfort distance in two brothers with BMD presenting with the same genetic deletion and a healthy control. When possible, we collected neuropsychological and psychopathological assessments. Our BMD patients were significantly different in interoceptive accuracy, with patient 1 being extremely accurate and patient 2 being significantly less accurate than his brother but more accurate than the control. Interestingly, they presented opposite patterns of interpersonal distance. Patient 1 was comfortable with very short interpersonal distance (≤50 cm from the confederate/object) vs the control and patient 2. By contrast, patient 2 preferred larger distance vs the control and patient 1. Patient 1 also presented difficulties in social and emotional skills on the psychopathological assessment. We are aware this is a small sample; nonetheless, this is also the first description of such aspects in BMD and the first report ever of such divergent behavioral pattern. As impaired social cognition affects the quality of life and social relationship, further studies are needed for a closer understanding of involved mechanisms.

A novel biomarker of fibrofatty replacement in dystrophinopathies identified by integrating transcriptome, magnetic resonance imaging, and pathology data.

We aimed to analyse genome-wide transcriptome differences between Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD) patients and identify biomarkers that correlate well with muscle magnetic resonance imaging (MRI) and histological fibrofatty replacement in both patients, which have not been reported. One hundred and one male patients with dystrophinopathies (55 DMD and 46 BMD) were enrolled. Muscle-derived genome-wide RNA-sequencing was performed in 31 DMD patients, 29 BMD patients, and 11 normal controls. Fibrofatty replacement was scored on muscle MRI and histological levels in all patients. A unique pipeline, single-sample gene set enrichment analysis combined with Spearman's rank correlations (ssGSEA-Cor) was developed to identify the most correlated gene signature for fibrofatty replacement. Quantitative real-time PCR (qRT-PCR) analysis, western blot analysis, and single-nucleus RNA-sequencing (snRNA-seq) were performed in the remaining patients to validate the most correlated gene signature. Comparative transcriptomic analysis revealed that 31 DMD muscles were characterized by a significant increase of inflammation/immune response and extracellular matrix remodelling compared with 29 BMD muscles (P<0.05). The ssGSEA-Cor pipeline revealed that the gene set of CDKN2A and CDKN2B was the most correlated gene signature for fibrofatty replacement (histological rs =0.744, P<0.001; MRI rs =0.718, P<0.001). Muscle qRT-PCR confirmed that CDKN2A mRNA expression in both 15 DMD (median=25.007, P<0.001) and 12 BMD (median=5.654, P<0.001) patients were significantly higher than that in controls (median=1.101), while no significant difference in CDKN2B mRNA expression was found among DMD, BMD, and control groups. In the 27 patients, muscle CDKN2A mRNA expression respectively correlated with muscle MRI (rs =0.883, P<0.001) and histological fibrofatty replacement (rs =0.804, P<0.001) and disease duration (rs =0.645, P<0.001) and North Star Ambulatory Assessment total scores (rs =-0.698, P<0.001). Muscle western blot analysis confirmed that both four DMD (median=2.958, P<0.05) and four BMD (median=1.959, P<0.01) patients had a significantly higher level of CDKN2A protein expression than controls (median=1.068). The snRNA-seq analysis of two DMD muscles revealed that CDKN2A was mainly expressed in fibro-adipogenic progenitors, satellite cells, and myoblasts. We identify CDKN2A expression as a novel biomarker of fibrofatty replacement, which might be a new target for antifibrotic therapy in dystrophinopathies.

On genotype-phenotype relationship of dystrophinopathies among Iranian population.

Background: Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD) are inherited X-linked disorders resulting from alterations in the dystrophin gene. Genotype-phenotype matching studies have revealed a link between disease severity, the amount of muscle dystrophin, and the extent of mutation/deletion on the dystrophin gene. This study aimed to assess the relationship between genetic alterations in the dystrophin gene and the clinical status of patients with dystrophinopathies among the Iranian population. Methods: This cross-sectional study examined 54 patients with muscle weakness caused by abnormalities in the dystrophin gene at a hospital affiliated to Isfahan University of Medical Sciences, Isfahan, Iran, in 2021. The participants' demographic information, including age, family history of muscle dystrophies, and family history of other medical diseases as well as the type of muscular dystrophy were recorded. Furthermore, the number and region of deleted exons based on dystrophy types were also evaluated using multiplex ligation-dependent probe amplification (MLPA). The patients' gaits were also assessed as using a wheelchair, the presence of waddling gaits, or toe gaits. The patients' clinical status and the coexistence of pulmonary, bulbar, and mental conditions were also examined and compared between the two groups of dystrophinopathies. Results: In this study, 54 patients with dystrophinopathy with the mean age of 16.63 ± 12.10 years were evaluated, of whom 22 (40.7%) and 30 (55.6%) patients were classified as BMD and DMD, respectively. The most affected regions with deleted exons were exons 45-47 (n = 5) and 45-48 (n = 4) in patients with BMD, while exons 45, 48-52, 51-55, and 53 (2 cases per exon) were the most common affected exons in patients with DMD. Further analyses revealed that deletions in exons 45-47 and 51-55 were significantly associated with older and younger ages at the onset of becoming wheelchair-bound in patients with dystrophy, respectively. The hotspot range in both BMD and DMD was within exons 45-55 (n = 15 for each group); 63% of the patients had alterations on the dystrophin gene within this range [30 patients (68.18%) in the BMD group, 15 patients (53.57%) in the DMD group]. Conclusion: Exon deletion was the most common genetic alteration in patients with dystrophinopathies. No significant difference was observed between DMD and BMD regarding the number of deleted exons. Deletions in exons 45-47 and 51-55 were linked to later and earlier onset of becoming wheelchair-bound, respectively.

Методические рекомендации: прогрессирующая мышечная дистрофия Дюшенна. Прогрессирующая мышечная дистрофия Беккера. Ранняя диагностика. Терапия не зарегистрированными на территории Российской федерации лекарственными препаратами

Supplement to the 2023 Issue 6 (Volume 102) of the Journal PEDIATRIA named after G.N. Speransky. Guidelines for Practitioners: Duchenne Muscular Dystrophy (DMD). Becker Muscular Dystrophy (BMD). Early diagnosis. Therapy with the use of drugs that are currently not registered properly in Russia/by the Ministry of Healthcare of Russia. DOI: 10.24110/0031-403X-2023-102-6-217-256. https://doi.org/10.24110/0031-403X-2023-102-6-217-256

Becker Muscular Dystrophy: Could Altering the Natural History of Decline Help Tackle Unmet Medical Need?

This symposium was held as part of the 28th International Annual Congress of the World Muscle Society (WMS), held in Charleston, South Carolina, USA. Speakers reviewed the natural history of Becker muscular dystrophy (Becker), outlined the top line, 12-month data from the ARCH open label study of investigational agent EDG-5506, and aimed to put those results into clinical context. Becker is a serious rare disease with significant physical, emotional, financial, and social impact on the affected individuals and their caregivers. Once function begins to decline, males affected by the progressive X-linked genetic disorder continue to irreversibly lose muscle, ultimately leading to the loss of ambulatory and cardiopulmonary function. After discussing the aetiology of the condition, Erik Niks, Paediatric and Adult Neurologist, Leiden University Medical Center (LUMC), the Netherlands, presented the findings of natural history studies. They showed that while the age at which decline begins varies, once it does start, patients tend to experience a consistent decline in function equivalent to around 1.2–1.3 North Star Ambulatory Assessment (NSAA) points each year. This finding, combined with data on using MRI as a biomarker of disease progression, provides an evidence-based framework for clinical trial design, he argued. Sam Collins, Vice President of clinical development, Edgewise Therapeutics, Boulder, Colorado, USA, then presented topline 12-month data from the ARCH study. It found that EDG-5506 was well tolerated, and, importantly, recorded the stabilisation of functional assessments, including the NSAA, with a trend towards improvement, as well as rapid, sustained, and significant decreases in biomarkers of progression, including those related to muscle damage. Putting the ARCH study data into context, Barry Byrne, Director of the Health Center for Advanced Therapeutics and Powell Gene Therapy Center, University of Florida (UF), Gainesville, USA, explained exactly how declining NSAA status translated into life-altering function loss. Stabilising function, or even reducing the speed of decline, was an important goal for patients, he said, adding that meeting it could help to address significant unmet medical need.

Effectiveness of conservative non-pharmacological interventions in people with muscular dystrophies: a systematic review and meta-analysis

IntroductionManagement of muscular dystrophies (MD) relies on conservative non-pharmacological treatments, but evidence of their effectiveness is limited and inconclusive.ObjectiveTo investigate the effectiveness of conservative non-pharmacological interventions for MD physical management.MethodsThis...

Becker muscular dystrophy: Cardiac involvement and mild heterogeneous phenotype in a family with EXONS 45–48 deletion

Becker muscular dystrophy: Cardiac involvement and mild heterogeneous phenotype in a family with EXONS 45–48 deletion

Mutation spectrum analysis of DMD gene in Indonesian Duchenne and Becker muscular dystrophy patients.

Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD) are allelic disorders caused by mutations in the DMD gene. The full mutation spectrum of the DMD gene in Indonesian patients is currently unknown. Mutation-specific therapies are currently being developed, such as exon skipping or stop codon read-through therapy. This study was conducted with the aim of identifying the mutation spectrum of the DMD gene in Indonesia to guide future development and application of feasible therapeutic strategies. This study is a cross sectional study that enrolled 43 male patients with a clinical suspicion of DMD or BMD. Multiplex ligation-dependent probe amplification (MLPA) reaction was performed to screen for the common mutations in the DMD gene. Out of 43 subjects, deletions accounted for 69.77% (n=30) cases, while duplications were found in 11.63% (n=5) cases. One novel duplication spanning exons 2 to 62 was identified. Deletion mutations clustered around the distal (66.67%) and proximal (26.67%) hot spot regions of the DMD gene while duplication mutations were observed solely at the proximal region. Two false positive cases of single exon deletion detected through MLPA were attributed to sequence mutations affecting primer ligation sites, confirming the need to validate all single exon deletions when using this screening method. Analysis of available maternal DNA samples showed that the rate of de novo mutations (48.15%) appears higher than expected in this population. Out of 31 patients who were classified as DMD based on clinical and genotype characterizations, 60.47% (n=26) of cases were suitable for exon skipping therapy. This is the first comprehensive study showing the feasibility of implementing the MLPA method for routine screening of DMD patients in Indonesia. This is also the first study showing the potential applicability of exon skipping therapy in the majority of DMD cases in the country.

Effectiveness of a 5-Week Virtual Reality Telerehabilitation Program for Children With Duchenne and Becker Muscular Dystrophy: Prospective Quasi-Experimental Study.

Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD) are neuromuscular diseases. DMD is the most prevalent in children. It affects dystrophin production, reducing the patient's mobility and quality of life. New technologies have become a part of physical therapy in DMD and BMD. During the COVID-19 pandemic, conducting telerehabilitation through virtual reality-based games could help these children maintain their physical abilities. This study examined if the use of a virtual platform in a multimodal intervention program changes the results of the 6-minute walk test (6MWT) in children with DMD and BMD. The main objective was to test whether children with DMD and BMD obtain different results on the 6MWT after completing 10 telerehabilitation treatment sessions. The secondary objective was to measure whether other specific motor scales also produce different results after the 10 defined sessions. This was a descriptive, open, and quasi-experimental study with a prospective A-B (control-intervention) design. A sample of 12 participants who fulfilled the inclusion criteria followed the program for 5 weeks with 10 telerehabilitation sessions. During the sessions, the participants used virtual reality glasses to train for the treatment goals. All participants were assessed in person before and after the intervention. Analysis was performed using R software according to the different functional assessments performed for each test. The participants showed a 19.55-meter increase in the 6MWT. Motor function also remained stable according to other scales used to assess it. The North Start Ambulatory Assessment scores were stable in both treatment conditions (P=.20). Furthermore, the timed up and go test results were 0.1 seconds faster in the telerehabilitation condition, and the Motor Function Measure in all of the 3 dimensions showed no significant differences (P=.08). Finally, the Effort Perception Infant scale showed that during the training, fatigue increased in the middle and decreased by the end of the sessions, but the perception throughout the sessions was lower even as the exercise intensity increased. There were no differences between conventional and telerehabilitation treatments, so the telerehabilitation tool could be used without harming children with DMD and BMD, facilitating their access to therapies and stimulating learning to maintain their functional capacity. Therefore, telerehabilitation in general may be helpful in maintaining motor function in children with DMD and BMD. The learning effect helped reduce the feeling of fatigue in the children during the program.

Cognitive abnormalities in Becker muscular dystrophy: a mysterious link between dystrophin deficiency and executive functions

BackgroundDistrophinopathies are a heterogeneous group of neuromuscular disorders due to mutations in the DMD gene. Different isoforms of dystrophin are also expressed in the cerebral cortex and Purkinje cells. Despite cognitive abnormalities in Duchenne muscular dystrophy subjects that have been described in the literature, little is known about a comprehensive cognitive profile in Becker muscular dystrophy patients.AimThe aim of this study was to assess cognitive functioning in Becker muscular dystrophy patients by using an extensive neuropsychological battery. Our hypothesis is that the most impaired functions are the highly intentional and conscious ones, such as working memory functions, which require a prolonged state of cellular activation.MethodsWe performed an extensive neuropsychological assessment on 28 Becker muscular dystrophy patients from 18 to 65 years old. As control subjects, we selected 20 patients with limb-girdle muscular dystrophy, whose clinical picture was similar except for cognitive integrity. The evaluation, although extended to all areas, was focused on prefrontal control skills, with a distinction between inhibitory processes of selective attention and activating processes of working memory.Results and conclusionsSignificant underperformances were found exclusively in the Dual Task and PASAT tests, to demonstrate a selective impairment of working memory that, while not causing intellectual disability, reduces the intellectual potential of patients with Becker muscular dystrophy.

Ryanodine receptor type 1 content decrease-induced endoplasmic reticulum stress is a hallmark of myopathies.

Decreased ryanodine receptor type 1 (RyR1) protein levels are a well-described feature of recessive RYR1-related myopathies. The aim of the present study was twofold: (1) to determine whether RyR1 content is also decreased in other myopathies and (2) to investigate the mechanisms by which decreased RyR1 protein triggers muscular disorders. We used publicly available datasets, muscles from human inflammatory and mitochondrial myopathies, an inducible muscle-specific RYR1 recessive mouse model and RyR1 knockdown in C2C12 muscle cells to measure RyR1 content and endoplasmic reticulum (ER) stress markers. Proteomics, lipidomics, molecular biology and transmission electron microscopy approaches were used to decipher the alterations associated with the reduction of RyR1 protein levels. RYR1 transcripts were reduced in muscle samples of patients suffering from necrotizing myopathy (P=0.026), inclusion body myopathy (P=0.003), polymyositis (P<0.001) and juvenile dermatomyositis (P<0.001) and in muscle samples of myotonic dystrophy type 2 (P<0.001), presymptomatic (P<0.001) and symptomatic (P<0.001) Duchenne muscular dystrophy, Becker muscular dystrophy (P=0.004) and limb-girdle muscular dystrophy type 2A (P=0.004). RyR1 protein content was also significantly decreased in inflammatory myopathy (-75%, P<0.001) and mitochondrial myopathy (-71%, P<0.001) muscles. Proteomics data showed that depletion of RyR1 protein in C2C12 myoblasts leads to myotubes recapitulating the common molecular alterations observed in myopathies. Mechanistically, RyR1 protein depletion reduces ER-mitochondria contact length (-26%, P<0.001), Ca2+ transfer to mitochondria (-48%, P=0.002) and the mitophagy gene Parkinson protein 2 transcripts (P=0.037) and induces mitochondrial accumulation (+99%, P=0.005) and dysfunction (P<0.001). This was associated to the accumulation of deleterious sphingolipid species. Our data showed increased levels of the ER stress marker chaperone-binding protein/glucose regulated protein 78, GRP78-Bip, in RyR1 knockdown myotubes (+45%, P=0.046), in mouse RyR1 recessive muscles (+58%, P=0.001) and in human inflammatory (+96%, P=0.006) and mitochondrial (+64%, P=0.049) myopathy muscles. This was accompanied by increased protein levels of the pro-apoptotic protein CCAAT-enhancer-binding protein homologous protein, CHOP-DDIT3, in RyR1 knockdown myotubes (+27%, P<0.001), mouse RyR1 recessive muscles (+63%, P=0.009), human inflammatory (+50%, P=0.038) and mitochondrial (+51%, P=0.035) myopathy muscles. In publicly available datasets, the decrease in RYR1 content in myopathies was also associated to increased ER stress markers and RYR1 transcript levels are inversely correlated with ER stress markers in the control population. Decreased RyR1 is commonly observed in myopathies and associated to ER stress in vitro, in mouse muscle and in human myopathy muscles, suggesting a potent role of RyR1 depletion-induced ER stress in the pathogenesis of myopathies.