Clinical and Molecular Spectrum of Muscular Dystrophies (MDs) with Intellectual Disability (ID): a Comprehensive Overview

Unraveling the bidirectional relationship between muscle inflammation and satellite cells activity: influencing factors and insights

Inflammation stands as a vital and innate function of the immune system, essential for maintaining physiological homeostasis. Its role in skeletal muscle regeneration is pivotal, with the activation of satellite cells (SCs) driving the repair and generation of new myofibers. However, the relationship between inflammation and SCs is intricate, influenced by various factors. Muscle injury and repair prompt significant infiltration of immune cells, particularly macrophages, into the muscle tissue. The interplay of cytokines and chemokines from diverse cell types, including immune cells, fibroadipogenic progenitors, and SCs, further shapes the inflammation-SCs dynamic. While some studies suggest heightened inflammation associates with reduced SC activity and increased fibro- or adipogenesis, others indicate an inflammatory stimulus benefits SC function. Yet, the existing literature struggles to delineate clearly between the stimulatory and inhibitory effects of inflammation on SCs and muscle regeneration. This paper comprehensively reviews studies exploring the impact of pharmacological agents, dietary interventions, genetic factors, and exercise regimes on the interplay between inflammation and SC activity.

The latest developments in synthetic approaches to Duchenne muscular dystrophy

INTRODUCTION

Duchenne muscular dystrophy (DMD) is a rare X-linked genetic disorder caused by mutations in the dystrophin gene, leading to an almost complete absence of dystrophin, which is essential for muscle cell structure and function. This resulting muscle deterioration and fibrosis, eventually causes respiratory failure and cardiomyopathy. While there is currently no cure, existing therapies aim to prolong survival and alleviate symptoms.

AREAS COVERED

This paper reviews current and emerging therapies for DMD, focusing on their safety and efficacy. Although corticosteroids remain the standard treatment, newly approved drugs such as exon-skipping therapies, vamorolone, delandistrogene moxeparvovec, and givinostat provide new treatment options. Additionally, future therapies, including gene therapy, stem cell treatments, and anti-fibrotic agents, show promise for clinical application.

EXPERT OPINION

Advancements in DMD treatments have expanded patient options. While gene therapy offers potential for correcting the genetic defect and alleviating symptoms, corticosteroids remain the most cost-effective and well-researched treatment. This is partly due to the lack of compelling long-term safety and efficacy data for gene therapies. The accelerated FDA review process has enabled faster approval of new medications; however many have provided minimal clinical benefit to patients. Despite these challenges, continued drug development and innovative research offer hope to patients.

Effects of a neuropsychosocial teleassistance intervention on social cognition and health-related quality of life of pediatric patients with neuromuscular diseases

OBJECTIVE

This study aimed to determine the effects of a neuropsychosocial teleassistance group-based intervention on improving social cognitive functioning and health-related quality of life (HRQoL) in pediatric neuromuscular diseases (NMD).

METHODS

Thirty-five pediatric patients with NMD were assigned to the neuropsychosocial intervention program (n = 20) or waiting list control condition (n = 15). The intervention group received an integrative approach that combines training in social cognition with cognitive behavioral therapy. All participants completed a neuropsychological and clinical assessment at baseline and follow-up, which included tests of social cognition, both for emotion recognition and theory of mind, and HRQoL. Repeated-measures multivariate analysis of covariance was used to determine the effects of the teleassistance program.

RESULTS

Group × Time interactions revealed significant improvements in the intervention group as compared with the control group for different social cognition's indicators (AR NEPSY-II: p = .003, η2p = .24; TM NEPSY: p < .001, η2p = .35; Verbal task: p < .001, η2p = .35; Happé's Strange Stories: p = .049, η2p = .11) and HRQoL (Psychosocial health: p = .012, η2p = .18; Emotional functioning: p = .037, η2p = 0.13; Social functioning: p = .006, η2p = .21; Total: p = .013, η2p = .17), showing medium to large effects.

CONCLUSIONS

Patients receiving the neuropsychosocial intervention showed improvements in their social cognition performance and psychosocial HRQoL, providing evidence about the positive effects of the program in pediatric patients with NMD. This should be considered in further research and interventions in this field.

Difficulties in social cognitive functioning among pediatric patients with muscular dystrophies

Introduction

Pediatric muscular dystrophies (MDs) are a heterogeneous group of rare neuromuscular diseases characterized by progressive muscle degeneration. A neuropsychosocial approach is crucial for these patients due to associated cognitive, behavioral, and psychiatric comorbidities; however, the social cognitive domain has not been adequately addressed.

Methods

This study aimed to analyze on social cognition performance in a pediatric MD patient cohort. This cross-sectional study included 32 pediatric patients with MD and 32 matched-healthy controls. The Social Perception Domain of the NEPSY-II, the Reading the Mind in the Eyes Test-Child and Happé's Strange Stories Test were administered. General intelligence and behavioral and emotional symptoms were controlled for to eliminate covariables' possible influence. The assessments were performed remotely.

Results

Children with MDs performed significantly worse on most of the social cognition tasks. The differences found between the groups could be explained by the level of general intelligence for some aspects more related to theory of mind (ToM) (TM NEPSY-II: F = 1.703, p = .197; Verbal task: F = 2.411, p = .125; RMET-C: F = 2.899, p = .094), but not for emotion recognition. Furthermore, these differences were also independent of behavioral and emotional symptoms.

Discussion

In conclusion, social cognition is apparently impaired in pediatric patients with MD, both for emotion recognition and ToM. Screening assessment in social cognition should be considered to promote early interventions aimed at improving these patient's quality of life.

Long-term clinical and MRI follow-up in two POMT2-related limb girdle muscular dystrophy (LGMDR14) patients

INTRODUCTION

POMT2-related limb girdle muscular dystrophy (LGMDR14) is a rare muscular dystrophy caused by mutations in the POMT2 gene. Thus far only 26 LGMDR14 subjects have been reported and no longitudinal natural history data are available.

CASE REPORT

We describe two LGMDR14 patients followed for 20 years since infancy. Both patients presented a childhood-onset, slowly progressive pelvic girdle muscular weakness leading to loss of ambulation in the second decade in one patient, and cognitive impairment without detectable brain structural abnormalities. Glutei, paraspinal, and adductor muscles were the primarily involved muscles at MRI.

DISCUSSION

This report provides natural history data on LGMDR14 subjects, with a focus on longitudinal muscle MRI. We also reviewed the LGMDR14 literature data, providing information on the LGMDR14 disease progression. Considering the high prevalence of cognitive impairment in LGMDR14 patients, a reliable application of functional outcome measures can be challenging, therefore a muscle MRI follow-up to assess disease evolution is recommended.

Perspectives on the advances in the pharmacotherapeutic management of Duchenne muscular dystrophy

INTRODUCTION

: Duchenne muscular dystrophy (DMD) is a progressive genetic disease characterized by muscular weakness with a global prevalence of 7.1 cases per 100,000 males. DMD is caused by mutations of the dystrophin gene on the X chromosome which is responsible for dystrophin protein production. Dystrophin is a cytoskeletal protein that contributes to structural support in muscle cells. DMD mutations result in dystrophin protein deficiency which leads to muscle damage and the associated clinical presentation.

AREAS COVERED

: Corticosteroids such as prednisone and deflazacort are routinely given to patients to treat inflammation, but their use is limited by the occurrence of side effects and a lack of standardized prescribing. Exon-skipping medications are emerging as treatment options for a small portion of DMD patients even though efficacy is uncertain. Many new therapeutics are under development that target inflammation, fibrosis, and dystrophin replacement.

EXPERT OPINION

: Because of side effects associated with corticosteroid use, there is need for better alternatives to the standard of care. Excessive cost is a barrier to patients receiving medications that have yet to have established efficacy. Additional therapies have the potential to help patients with DMD, although most are several years away from approval for patient use.

Implications of notch signaling in duchenne muscular dystrophy

This review focuses upon the implications of the Notch signaling pathway in muscular dystrophies, particularly Duchenne muscular dystrophy (DMD): a pervasive and catastrophic condition concerned with skeletal muscle degeneration. Prior work has defined the pathogenesis of DMD, and several therapeutic approaches have been undertaken in order to regenerate skeletal muscle tissue and ameliorate the phenotype. There is presently no cure for DMD, but a promising avenue for novel therapies is inducing muscle regeneration via satellite cells (muscle stem cells). One specific target using this approach is the Notch signaling pathway. The canonical Notch signaling pathway has been well-characterized and it ultimately governs cell fate decision, cell proliferation, and induction of differentiation. Additionally, inhibition of the Notch signaling pathway has been directly implicated in the deficits seen with muscular dystrophies. Here, we explore the connection between the Notch signaling pathway and DMD, as well as how Notch signaling may be targeted to improve the muscle degeneration seen in muscular dystrophies.

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.