Neurodevelopmental, behavioral, and emotional symptoms in Becker muscular dystrophy

Towards harmonization of clinical tools for assessing Brain Involvement in Dystrophinopathies (BIND); report of four expert workshops: Newcastle, Leiden, Rome, Paris

As part of an international project aimed at improving the characterization of brain involvement in Duchenne and Becker Muscular Dystrophies, a group of clinicians, researchers and family associations held multiple meetings between March 2021 and March 2024 to identify and reach a consensus on the possible tools that could assess the spectrum of neurocognitive and neurobehavioral brain comorbidities in dystrophinopathies. Consensus was achieved on which of these tools should be used across different settings, ranging from screening to clinical practice and scientific research. Screening questionnaires were found to be valuable not only for providing epidemiological data but also for raising awareness among the Duchenne community and professionals. More standardised and detailed online questionnaires, combined with in-depth clinical assessments can help better identify the profile of brain comorbidities and plan appropriate interventions. Additionally, the information gathered from assessing multiple features of brain involvement can be used to explore correlations with other aspects, such as the regional expression of the different dystrophin isoforms, brain imaging, and the animal models deficient in these isoforms.

The bench to bedside journey of tricyclo-DNA antisense oligonucleotides for the treatment of Duchenne muscular dystrophy

The development of antisense oligonucleotide (ASO)-based therapeutics has made tremendous progress over the past few years, in particular for the treatment of neuromuscular disorders such as Duchenne muscular dystrophy and spinal muscular atrophy. Several ASO drugs have now reached market approval for these diseases and many more are currently under clinical evaluation. Among them, ASOs made of the tricyclo-DNA originally developed by Christian Leumann have shown particularly interesting properties and demonstrated promise for the treatment of Duchenne muscular dystrophy. In this review, we examine the bench to bedside journey of tricyclo-DNA-ASOs from their early preclinical evaluation as fully phosphorotiated-ASOs to the latest generation of lipid-conjugated-ASOs. Finally we discuss the remaining challenges of ASO-mediated exon-skipping therapy for DMD and future perspectives for this promising chemistry of ASOs.

Prevalence of Attention-Deficit/Hyperactivity Disorder and Autism Spectrum Disorder in Individuals With Dystrophinopathy at a Tertiary Care Center in Chicago

OBJECTIVE

To study the prevalence of attention-deficit/hyperactivity disorder (ADHD) and autism spectrum disorder (ASD) in individuals with dystrophinopathy compared with the general population.

METHODS

Retrospective chart review to examine the prevalence of ADHD and ASD, diagnosed both formally and informally, in individuals with dystrophinopathy receiving care in the multidisciplinary neuromuscular clinic at the Ann and Robert H. Lurie Children's Hospital of Chicago.

RESULTS

Our results demonstrate an ADHD prevalence of 18.40% and ASD prevalence of 12.73%, both significantly higher than those reported for the general population. Our results revealed a significant association between ADHD diagnosis and a positive family history but did not show a statistically significant association between prevalence of ADHD and the use of steroids.

CONCLUSION

Based on our current study results, we plan to further evaluate the prevalence, in a prospective cross-sectional manner, using validated screens for both ADHD and ASD.

Genetic counseling for the dystrophinopathies-Practice resource of the National Society of Genetic Counselors

The dystrophinopathies encompass the phenotypically variable forms of muscular dystrophy caused by pathogenic variants in the DMD gene. The dystrophinopathies include the most common inherited muscular dystrophy among 46,XY individuals, Duchenne muscular dystrophy, as well as Becker muscular dystrophy and other less common phenotypic variants. With increased access to and utilization of genetic testing in the diagnostic and carrier setting, genetic counselors and clinicians in diverse specialty areas may care for individuals with and carriers of dystrophinopathy. This practice resource was developed as a tool for genetic counselors and other health care professionals to support counseling regarding dystrophinopathies, including diagnosis, health risks and management, psychosocial needs, reproductive options, clinical trials, and treatment. Genetic testing efforts have enabled genotype/phenotype correlation in the dystrophinopathies, but have also revealed unexpected findings, further complicating genetic counseling for this group of conditions. Additionally, the therapeutic landscape for dystrophinopathies has dramatically changed with several FDA-approved therapeutics, an expansive research pathway, and numerous clinical trials. Genotype-phenotype correlations are especially complex and genetic counselors' unique skill sets are useful in exploring and explaining this to families. Given the recent advances in diagnostic testing and therapeutics related to dystrophinopathies, this practice resource is a timely update for genetic counselors and other healthcare professionals involved in the diagnosis and care of individuals with dystrophinopathies.

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.

Natural history of Becker muscular dystrophy: a multicenter study of 225 patients

OBJECTIVE

Becker muscular dystrophy (BMD) is a milder variant of Duchenne muscular dystrophy (DMD), a lethal X-linked muscular disorder. Here, we aim to investigat the clinical involvement of skeletal, respiratory, cardiac, and central nervous systems in patients with BMD, as well as genotype-phenotype relationships.

METHODS

This nationwide cohort study investigated the clinical manifestations and genotype-phenotype relationships in 225 patients with BMD having in-frame deletion from 22 medical centers. The primary outcome was to elucidate the association of genotype with skeletal muscle, respiratory, cardiac, and central nervous system disorders. Descriptive statistics were used to analyze the data.

RESULTS

The average age of the subjects was 31.5 (range, 1-81) years. Initial symptoms of BMD were muscular (60%), followed by asymptomatic hypercreatine kinasemia (32.4%) and central nervous system disorders (5.3%). Gait disturbance was observed in 53.8% of patients and the average age at wheelchair introduction was 36.5 years. The ventilator introduction rate was 6.7% at an average age of 36.6 years. More than 30% of patients had an abnormal electrocardiogram and approximately 15% had heart failure symptoms. Cardiac function on echocardiography varied significantly among the patients. The frequencies of seizures and intellectual/developmental disability were 8.0% and 16.9%, respectively. Exon 45-47deletion (del) was the most common (22.6%), followed by exon 45-48del (13.1%). Patients with exon 45-49del patients demonstrated severe skeletal muscle damage. Patients with exon 45-47del and exon 45-55del patients did not require ventilator use.

INTERPRETATION

The study provides important prognostic information for patients and clinicians to establish therapy plans and to implement preventative medicine.

Psychological test usage in duchenne muscular dystrophy: An EU multi-centre study

AIM

During the last two decades brain related comorbidities of Duchenne have received growing scientific and clinical interest and therefore systematic assessment of cognition, behaviour and learning is important. This study aims to describe the instruments currently being used in five neuromuscular clinics in Europe as well as the diagnoses being made in these clinics.

METHOD

A Delphi based procedure was developed by which a questionnaire was sent to the psychologist in five of the seven participating clinics of the Brain Involvement In Dystrophinopathy (BIND) study. Instruments and diagnoses being used were inventoried for three domains of functioning (cognition, behaviour and academics) and three age groups (3-5 years, 6-18 years and adulthood 18+ years).

RESULTS

Data show wide diversity of tests being used in the five centres at different age groups and different domains. For the intelligence testing there is consensus in using the Wechsler scales, but all other domains such as memory, attention, behavioural problems and reading are tested in very different ways by different instruments in the participating centres.

CONCLUSION

The heterogeneity of tests and diagnoses being used in current clinical practice underlines the importance for developing a Standard Operating Procedure (SOP) to improve both clinical practice and scientific research over different countries and improve comparative work.

Dystrophin Genotype and Risk of Neuropsychiatric Disorders in Dystrophinopathies: A Systematic Review and Meta-Analysis

BACKGROUND

Dystrophinopathies are associated with neuropsychiatric disorders due to alterations in dystrophin/DMD expression.

OBJECTIVE

The objective was to estimate the association of developmental disorders, autism spectrum disorders (ASD), attention deficit hyperactivity disorder (ADHD), depression, anxiety disorders, and obsessive-compulsive disorder with the dystrophin/DMD genotype in population with dystrophinopathies.

METHODS

Systematic searches of Medline, Scopus, Web of Science, and Cochrane Library were performed from inception to September 2022. We included observational studies in the population with Becker or Duchenne muscular dystrophies (BMD, DMD) that estimated the prevalence of these disorders according to Dp140 and/or Dp71 genotype. Meta-analysis of the prevalence ratio (PR) of genotype comparisons was conducted for each disorder.

RESULTS

Ten studies were included in the systematic review. In BMD, Dp140+ vs. Dp140- and Dp71+ vs. Dp71- were associated with developmental disorders with a PR of 0.11 (0.04, 0.34) and 0.22 (0.07, 0.67), respectively. In DMD, Dp140+/Dp71+ vs. Dp140- /Dp71- had a PR of 0.40 (0.28, 0.57), and Dp71+ vs. Dp71- had a PR of 0.47 (0.36, 0.63) for ADHD. However, there was no association of genotype with ASD, only a trend was observed for Dp71+ vs. Dp71-, with a PR of 0.61 (0.35, 1.06). Moreover, the data showed no association of these isoforms with emotional-related disorders.

CONCLUSIONS

In BMD, Dp140 and Dp71 could be associated with developmental disorders, while ADHD might be associated with the Dp71 genotype in DMD. Further research is needed regarding Dp140 and Dp71, especially in DMD for ASD.

Prevalence of Neuropsychiatric Disorders in Duchenne and Becker Muscular Dystrophies: A Systematic Review and Meta-analysis

OBJECTIVE

To estimate the prevalence of neuropsychiatric disorders, including autism spectrum disorders (ASDs), attention-deficit hyperactivity disorder (ADHD), depression, anxiety disorders, and obsessive-compulsive disorder (OCD), in populations with Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD).

DATA SOURCES

MEDLINE (via PubMed), Scopus, Web of Science, and Cochrane Library from inception to November 2021.

STUDY SELECTION

Observational studies of individuals with DMD or BMD that estimated the prevalence of ASDs, ADHD, depression, anxiety disorders, and OCD in each population.

DATA EXTRACTION

A random-effects meta-analysis was performed on each outcome and each population (ie, DMD, BMD).

DATA SYNTHESIS

Twenty-three studies were included in the meta-analysis. In DMD, there was a prevalence of 7.0% of ASDs, 18.0% of ADHD, 11.0% of depression, 24.0% of anxiety disorders, and 12.0% of OCD. Furthermore, in BMD, there was a prevalence of 6.0% of ASDs, 28.0% of ADHD, 7.0% of depression, 25.0% of anxiety disorders, and 7.0% of OCD.

CONCLUSIONS

The prevalence of these neuropsychiatric disorders is higher among patients with DMD or BMD than among the general population, and the presence of these disorders may negatively influence optimal medical management.

Dystrophinopathy Phenotypes and Modifying Factors in DMD Exon 45-55 Deletion

OBJECTIVE

Duchenne muscular dystrophy (DMD) exon 45-55 deletion (del45-55) has been postulated as a model that could treat up to 60% of DMD patients, but the associated clinical variability and complications require clarification. We aimed to understand the phenotypes and potential modifying factors of this dystrophinopathy subset.

METHODS

This cross-sectional, multicenter cohort study applied clinical and functional evaluation. Next generation sequencing was employed to identify intronic breakpoints and their impact on the Dp140 promotor, intronic long noncoding RNA, and regulatory splicing sequences. DMD modifiers (SPP1, LTBP4, ACTN3) and concomitant mutations were also assessed. Haplotypes were built using DMD single nucleotide polymorphisms. Dystrophin expression was evaluated via immunostaining, Western blotting, reverse transcription polymerase chain reaction (PCR), and droplet digital PCR in 9 muscle biopsies.

RESULTS

The series comprised 57 subjects (23 index) expressing Becker phenotype (28%), isolated cardiopathy (19%), and asymptomatic features (53%). Cognitive impairment occurred in 90% of children. Patients were classified according to 10 distinct index-case breakpoints; 4 of them were recurrent due to founder events. A specific breakpoint (D5) was associated with severity, but no significant effect was appreciated due to the changes in intronic sequences. All biopsies showed dystrophin expression of >67% and traces of alternative del45-57 transcript that were not deemed pathogenically relevant. Only the LTBP4 haplotype appeared associated the presence of cardiopathy among the explored extragenic factors.

INTERPRETATION

We confirmed that del45-55 segregates a high proportion of benign phenotypes, severe cases, and isolated cardiac and cognitive presentations. Although some influence of the intronic breakpoint position and the LTBP4 modifier may exist, the pathomechanisms responsible for the phenotypic variability remain largely unresolved. ANN NEUROL 2022;92:793-806.

Congenital or Early Developing Neuromuscular Diseases Affecting Feeding, Swallowing and Speech – A Review of the Literature from January 1998 to August 2021

Background:

The knowledge about the impact of oral motor impairment in neuromuscular diseases (NMDs) is limited but increasing.

Objective:

The aim of this review was to collect and compile knowledge on how muscle weakness in congenital or early developing NMDs directly or indirectly affects feeding, swallowing, speech and saliva control.

Methods:

A literature search was performed in PubMed from January 1, 1998, to August 31, 2021. The keywords “feeding”, “dysphagia”, “swallowing”, “dysarthria”, “speech”, “drooling” and “sialorrhea” were used in combination with “paediatric neuromuscular disease” or specific diagnoses.

Results:

Sixty-five studies were selected for the review, 33 focused on feeding and swallowing, 11 on speech, four on a combination of feeding, swallowing, saliva control or speech and 17 general descriptions. Most of the studies reported on patients with a disorder affecting muscles. These studies show that muscle weakness and impaired motility affecting the muscles innervated by the cranial nerves may influence feeding, swallowing, and speech, and that respiratory function, general health and neurodevelopmental delay also influence these functions. Feeding impairment and breathing difficulties are common in NMDs. Lifesaving interventions such as tube feeding and ventilatory support are common in severe cases.

Conclusions:

Feeding impairment, dysphagia and dysarthria are prevalent in NMDs with congenital or early age of onset. Feeding and swallowing has been studied more than speech and saliva control. More children with NMD survive thanks to new treatment options and it is therefore urgent to follow up how these therapies may impact the development of feeding, swallowing, and speech.

Cognitive profile and neuropsychiatric disorders in Becker muscular dystrophy: A systematic review of literature

BACKGROUND

Brain co-morbidities in DMD are well-documented, less is known about the cognitive, behavioral and psychosocial functioning of patients with BMD.

METHODS

The systematic review was carried out on two databases (Pubmed and Scopus) according to the PRISMA guidelines. We included all research articles specific to BMD written after 1995.

RESULTS

Studies examining neuropsychological and neurobehavioral functioning in BMD are few and have several methods limitations. BMD population is characterized by high rates of cognitive impairment, with specific involvement of different cognitive areas. Unlike DMD, verbal skills are better preserved. Neurodevelopmental and emotional/behavioral disorders have great importance in BMD, due to their high prevalence. Lack of Dp140 or Dp71 can cause intellectual disability, these isoforms are probably responsible for the other brain-related comorbidities as well.

DISCUSSION

The results suggest that cognitive and neuropsychiatric comorbid symptoms may affect a significant proportion of BMD patients therefore it is important to mental health and neuropsychological screening. Finding tools for an adequate assessment is a priority in order to include brain outcome measures in clinical trials.

Dystrophin genetic variants and autism

Loss-of-function variants in the dystrophin gene, a well-known cause of muscular dystrophies, have emerged as a mutational risk mechanism for autism spectrum disorder (ASD), which in turn is a highly prevalent (~ 1%) genetically heterogeneous neurodevelopmental disorder. Although the association of intellectual disability with the dystrophinopathies Duchenne (DMD) and Becker muscular dystrophy (BMD) has been long established, their association with ASD is more recent, and the dystrophin genotype-ASD phenotype correlation is unclear. We therefore present a review of the literature focused on the ASD prevalence among dystrophinopathies, the relevance of the dystrophin isoforms, and most particularly the relevance of the genetic background to the etiology of ASD in these patients. Four families with ASD-DMD/BMD patients are also reported here for the first time. These include a single ASD individual, ASD-discordant and ASD-concordant monozygotic twins, and non-identical ASD triplets. Notably, two unrelated individuals, which were first ascertained because of the ASD phenotype at ages 15 and 5 years respectively, present rare dystrophin variants still poorly characterized, suggesting that some dystrophin variants may compromise the brain more prominently. Whole exome sequencing in these ASD-DMD/BMD individuals together with the literature suggest, although based on preliminary data, a complex and heterogeneous genetic architecture underlying ASD in dystrophinopathies, that include rare variants of large and medium effect. The need for the establishment of a consortia for genomic investigation of ASD-DMD/BMD patients, which may shed light on the genetic architecture of ASD, is discussed.

A case of delayed diagnosis of Becker muscular dystrophy due to underlying developmental disorders

BACKGROUND

Developmental disorders associated with Becker muscular dystrophy (BMD), possibly resulting from a lack of dystrophin in the brain, have been reported, but their importance is not fully understood. We report a case of a BMD patient who had been socially withdrawn due to mental retardation and autism spectrum disorder and could not receive appropriate medical services, resulting in delayed detection of severe cardiomyopathy and embolic strokes which developed as complications of BMD.

CASE REPORT

The case is a 41-year-old male. In elementary school, he was the slowest runner in his class and had poor grades. He started missing school due to bullying in junior high school and had been socially withdrawn for 24 years. He developed difficulty walking due to progressive muscle weakness in the extremities and lost ambulation at age 36. At age 41, he was referred to our hospital by public health support services to address his social withdrawal. Muscle biopsy led to the diagnosis of BMD. Psychological examination revealed mild mental retardation and autism spectrum disorder, which may have resulted in social isolation. He had severe cardiomyopathy and asymptomatic cerebral infarction due to heart failure.

CONCLUSION

In BMD patients, developmental disorders can potentially hinder access to appropriate medical treatment. BMD is an important differential diagnosis for physically disabled children with developmental disorders. Early intellectual and psychological interventions and evaluation of complications are important for improving patient prognosis and quality of life.

Psychopharmacological Treatments for Mental Disorders in Patients with Neuromuscular Diseases: A Scoping Review

Mental disorders are observed in neuromuscular diseases, especially now that patients are living longer. Psychiatric symptoms may be severe and psychopharmacological treatments may be required. However, very little is known about pharmacotherapy in these conditions. We aimed to summarize the current knowledge on the use of psychopharmacological treatments for mental disorders in patients living with a neuromuscular disease. A scoping review was performed using the methodology of the Joanna Briggs Institute. Four databases were searched from January 2000 to July 2021. Articles were screened based on titles and abstracts. Full-text papers published in peer-reviewed journals in English were selected. Twenty-six articles met eligibility criteria, all being case reports/series focusing on the psychopharmacological control of psychiatric symptoms for the following conditions: myasthenia gravis (n = 11), Duchenne (n = 5) and Becker (n = 3) muscular dystrophy, mitochondrial disorders (n = 3), glycogen storage disease (n = 1), myotonic dystrophy (n = 1), hyperkalemic periodic paralysis (n = 1), and congenital myasthenic syndrome (n = 1). None of the articles provided details on the decision-making process to choose a specific drug/regimen or on follow-up strategies to monitor safety and efficacy. Larger studies showing real-world data would be required to guide consensus-based recommendations, thus improving current standards of care and, ultimately, the quality of life of patients and their families.

RNA Targeting in Inherited Neuromuscular Disorders: Novel Therapeutic Strategies to Counteract Mis-Splicing

Neuromuscular disorders represent multifaceted abnormal conditions, with little or no cure, leading to patient deaths from complete muscle wasting and atrophy. Despite strong efforts in the past decades, development of effective treatments is still urgently needed. Advent of next-generation sequencing technologies has allowed identification of novel genes and mutations associated with neuromuscular pathologies, highlighting splicing defects as essential players. Deciphering the significance and relative contributions of defective RNA metabolism will be instrumental to address and counteract these malignancies. We review here recent progress on the role played by alternative splicing in ensuring functional neuromuscular junctions (NMJs), and its involvement in the pathogenesis of NMJ-related neuromuscular disorders, with particular emphasis on congenital myasthenic syndromes and muscular dystrophies. We will also discuss novel strategies based on oligonucleotides designed to bind their cognate sequences in the RNA or targeting intermediary of mRNA metabolism. These efforts resulted in several chemical classes of RNA molecules that have recently proven to be clinically effective, more potent and better tolerated than previous strategies.

Autism Spectrum Disorder and Duchenne Muscular Dystrophy: A Clinical Case on the Potential Role of the Dystrophin in Autism Neurobiology

A diagnosis of autism spectrum disorder is reported in up to 19% of dystrophinopathies. However, over the last ten years, only a few papers have been published on this topic. Therefore, further studies are required to analyze this association in depth and ultimately to understand the role of the brain dystrophin isoform in the pathogenesis of ASD and other neurodevelopmental disorders. In this paper, we report a clinical case of a patient affected by ASD and Duchenne muscular dystrophy, who carries a large deletion of the dystrophin gene. Then we present a brief overview of the literature about similar cases and about the potential role of the dystrophin protein in the neurobiology of autism spectrum disorder.

Complexity of skeletal muscle degeneration: multi-systems pathophysiology and organ crosstalk in dystrophinopathy

Duchenne muscular dystrophy is a highly progressive muscle wasting disorder due to primary abnormalities in one of the largest genes in the human genome, the DMD gene, which encodes various tissue-specific isoforms of the protein dystrophin. Although dystrophinopathies are classified as primary neuromuscular disorders, the body-wide abnormalities that are associated with this disorder and the occurrence of organ crosstalk suggest that a multi-systems pathophysiological view should be taken for a better overall understanding of the complex aetiology of X-linked muscular dystrophy. This article reviews the molecular and cellular effects of deficiency in dystrophin isoforms in relation to voluntary striated muscles, the cardio-respiratory system, the kidney, the liver, the gastrointestinal tract, the nervous system and the immune system. Based on the establishment of comprehensive biomarker signatures of X-linked muscular dystrophy using large-scale screening of both patient specimens and genetic animal models, this article also discusses the potential usefulness of novel disease markers for more inclusive approaches to differential diagnosis, prognosis and therapy monitoring that also take into account multi-systems aspects of dystrophinopathy. Current therapeutic approaches to combat muscular dystrophy are summarised.

The Neurocognitive and Behavioral Profiles of 3 Brothers With Becker Muscular Dystrophy

Becker muscular dystrophy patients generally carry in-frame mutations in the dystrophin gene, allowing the production of partially functional dystrophin protein. The presence of cognitive and behavioral comorbidities and the relation with the location of mutations has been scarcely investigated in Becker. This case report describes the neurocognitive and behavioral profiles of 3 brothers with Becker carrying an in-frame deletion of exons 45-48. The 3 cases underwent 2 consecutive neuropsychological assessments of which one assessment took place when they completed their primary education (age range of the cases: 11.2 -12.1 years). Intellectual abilities were normal to high and all cases had difficulties with processing speed and math. The brothers differed in intellectual abilities, executive functions, working memory, attention and reading abilities. Variability in cognitive development was noted as well. This report suggests that cognitive and behavioral functions in Becker vary regardless of gene mutation and exposer to similar environmental factors.