Search Results (146)

Neurofilaments (NFs) are the predominant type IV intermediate filaments in differentiated neurons, functioning not just as static scaffolds, but as active drivers of radial axonal growth and nerve conduction velocity. While their physical properties are well characterized, a critical gap remains in synthesizing how their dynamic assembly and developmental subunit switching directly dictate neurodegenerative outcomes. This review breaks down the molecular architecture and stepwise kinetic assembly of NFs, detailing their role in polarized transport and the formation of a protective viscoelastic gel network within axons. We specifically highlight the physiological expression switching of early subunits, such as alpha-internexin and peripherin, during neuronal maturation, a process often overlooked in traditional structural reviews. By examining how specific gene mutations and aberrant hyperphosphorylation trigger axonal transport jams and protein aggregation, we map the direct pathways leading to amyotrophic lateral sclerosis (ALS) and Charcot–Marie–Tooth (CMT) disease. Finally, we emphasize that a precise mechanistic decoding of NF structural dynamics and their pathological disruption is essential for understanding the fundamental etiology of these neurodegenerative conditions. Full article

Pathogenic variants in the PMP22 gene can lead to hereditary peripheral demyelinating neuropathies of varying severity, including hereditary neuropathy with liability to pressure palsies (HNPP), Charcot–Marie–Tooth disease types 1A and 1E (CMT1A, CMT1E), Roussy–Lévy syndrome, and Dejerine–Sottas disease (DSS). This study describes a novel deep intronic variant c.179-2809A>G in the PMP22 gene, identified in two unrelated Avar families from Dagestan republic, Russia. This variant was identified in nine patients. In seven cases, it was detected in a heterozygous state, leading to the development of HNPP. In two cases, this variant was found in a homozygous state, resulting in a more severe CMT1A phenotype (Dejerine–Sottas disease). The performed functional analysis allowed us to characterize the deleterious effect of this variant and propose an approach for personalized antisense therapy. This work demonstrates that, in Avar people with HNPP traits, variant c.179-2809A>G should be considered as disease-causing and included in standard genetic testing. Full article

Multiple sclerosis (MS) is a chronic immune-mediated demyelinating disorder of the central nervous system, traditionally considered distinct from neuromuscular diseases, which primarily affect the peripheral nervous system, neuromuscular junction, or skeletal muscle. Growing clinical and experimental evidence, however, indicates that certain neuromuscular disorders may coexist with MS or shared overlapping pathophysiological, immunological, and metabolic mechanisms. This narrative review summarizes reported associations between MS and neuromuscular diseases, with particular focus on well-characterized overlaps such as Leber hereditary optic neuropathy (LHON)-associated MS (Harding’s disease), combined central and peripheral demyelination (CCPD), and myasthenia gravis (MG) co-occurring with MS. Additional associations with Charcot–Marie–Tooth disease, mitochondrial disorders with MS-like phenotypes, inherited and autoimmune myopathies, and rare syndromes such as Guillain–Barré syndrome are also discussed. This review highlights proposed mechanisms potentially linking these conditions, including immune dysregulation, T- and B-cell-mediated autoimmunity, antibody-driven demyelination, mitochondrial dysfunction, impaired neuromuscular transmission, and molecular mimicry. Limitations of the current literature are acknowledged, particularly the predominance of case reports for rare associations and the frequent lack of systematic screening for coexisting disorders. By integrating evidence from case series, cohort studies, and mechanistic research, this review provides a comprehensive overview of the biological and clinical intersections between MS and neuromuscular diseases. Enhanced understanding of these overlaps may improve diagnostic accuracy, guide individualized management strategies, and inform future research on shared neuroimmunological and neurodegenerative pathways. Full article

ATP-binding cassette A1 (ABCA1) is a critical molecule in facilitating cholesterol transport in a variety of organs. In the nervous system, cholesterol supply is essential and rate-limiting for myelin biogenesis, which underlies efficient conduction of nerve impulses. When myelin is damaged or improperly formed due to genetic defects, a host of neurological symptoms may arise. A rare form of peripheral neuropathy in Tangier disease (TD) patients is associated with autosomal recessive mutations in ABCA1. Accordingly, when ABCA1 loses its function due to misexpression, the neuropathic phenotype is over-represented. Independently, studies have revealed the altered expression of ABCA1 and dysregulation of cholesterol metabolism in a host of inherited peripheral neuropathies engaging the Peripheral Myelin Protein 22 (PMP22), suggesting shared pathophysiology. While the role of ABCA1 has not been investigated broadly in peripheral nerves, the transporter molecule is a therapeutic target for human disorders, including multiple sclerosis and Alzheimer’s disease. Investigations in rodent models of type 1 Charcot–Marie–Tooth (CMT) neuropathies support the candidacy of this cholesterol transporter as a therapeutic target in efforts of peripheral myelin repair. Ongoing preclinical studies in central and peripheral nervous system disease models will provide critical information on the importance of ABCA1 as a target for disease modifying intervention. Full article

Mutations in the Mitofusin 2 (MFN2) gene cause Charcot–Marie–Tooth type 2A (CMT2A). Neurotrophin 3 (NT-3) is an autocrine factor that supports Schwann cell survival and differentiation, axon regeneration and myelination, neuromuscular junction (NMJ) integrity, and mitochondrial function. In this study, we assessed the efficacy of NT-3 gene therapy using the AAVrh74 serotype in the Mfn2^+/− mouse model for CMT2A. Although haploinsufficiency is not reported in CMT2A patients, our model shows some features of CMT2A, including axonal atrophy, muscle atrophy, length-dependent axon loss, and abnormal mitochondria, in muscle in the enzyme histochemistry. Eight-month-old Mfn2^+/− mice received a 3 × 10¹¹ vector genome dose of AAVrh74.tMCK.NT-3 intramuscularly, and functional, electrophysiological, and histological outcomes were assessed six months post-treatment. NT-3 gene therapy in Mfn2^+/− mice significantly improved grip strength and rotarod performance, and ameliorated electrophysiological abnormalities and NMJ denervation in lumbrical muscles. Additionally, our therapeutic approach improved muscle histopathology with reductions in mitochondrial abnormalities and oxidative stress. NT-3 further remodeled carbohydrate metabolism in muscle. Our study indicated that AAV.NT-3 gene therapy has a disease-modifying effect in the Mfn2^+/− model of CMT2A, providing further support for the translational potential of this surrogate gene therapy approach to CMT2A patients. Full article

The mitochondrial outer membrane (OMM) plays a crucial role in maintaining cellular homeostasis by regulating mitochondrial dynamics, organelle interactions, and stress responses. In peripheral neurons—cells with high metabolic demands and long axons—the OMM acts as a vital platform for coordinating bioenergetics, calcium signaling, and redox balance. Ganglioside-induced differentiation-associated protein 1 (GDAP1), an OMM-anchored protein, has emerged as a key regulator of mitochondrial fission and transport, redox homeostasis, and mitochondrial membrane contact sites (MCSs). Genetic variants in GDAP1 cause Charcot–Marie–Tooth disease (CMT), emphasizing its essential role in peripheral nerve function. This review highlights the multifaceted functions of GDAP1 in neuronal physiology and as a model protein that integrates organelle communication and mitochondrial biology. We further discuss how GDAP1 dysfunction leads to structural and functional impairments in peripheral neurons, proposing the OMM and its microenvironment as critical targets for therapeutic intervention in inherited neuropathies. Full article

Charcot–Marie–Tooth disease (CMT), caused by dominant loss-of-function mutations in DNM2, encoding the GTPase dynamin-2, impairs motor and sensory function. However, the respective contributions of muscle and nerve pathology, and the therapeutic potential of increasing DNM2 expression, remain unresolved. We evaluated tissue-targeted and systemic approaches to increase DNM2 in a mouse model carrying the common K562E-CMT mutation. Muscle-specific DNM2 overexpression from embryogenesis in Dnm2^K562E/+ mice ameliorated desmin and integrin mislocalization, membrane trafficking defects, mitochondrial abnormalities, and fibrosis in skeletal muscle, resulting in improved locomotor coordination despite persistent muscle atrophy. Conversely, systemic postnatal AAV delivery of human DNM2 increased DNM2 in muscle but failed to transduce nerves and paradoxically worsened the muscle pathology, producing centronuclear myopathy-like features. These findings reveal a primary pathogenic impact of DNM2-CMT mutation within skeletal muscle, independent of nerve involvement. Collectively, they underscore that precise DNM2 dosage is critical for neuromuscular homeostasis and reveal a narrow therapeutic window for safe and effective therapeutic intervention. This paradox, in which efforts to compensate for a loss-of-function neuropathy risk inducing a gain-of-function myopathy, highlights the need for tightly controlled modulation of DNM2 activity in future therapeutic strategies. Full article

Charcot–Marie–Tooth (CMT) disease represents the most prevalent inherited peripheral neuropathy with a broad range of clinical manifestations, inheritance patterns, and causative genes. The primary pathological hallmark is progressive degeneration, predominantly affecting sensory and motor neurons, leading to prominent sensory deficits and progressive motor impairments. While neuropathy-causing mutations in the ubiquitously expressed small heat shock protein HSPB1 account for a subset of axonal CMT cases, the mechanisms underlying the selective vulnerability of peripheral neurons remain poorly understood. In this review, we synthesize emerging evidence to reframe HSPB1-related CMT as a prototypical gene–environment interaction disorder. The unique anatomical exposure and high metabolic demands of the peripheral nervous system (PNS) render it particularly vulnerable to HSPB1 mutation-mediated homeostatic collapse, which manifests through three interconnected pathological axes: proteostatic disturbance, cytoskeletal dysregulation, and mitochondrial dysfunction. Crucially, these deficits converge to impair the stress adaptability of peripheral neurons, creating a maladaptive feedback loop wherein environmental stressors exacerbate intrinsic vulnerabilities. We further propose a phase-specific therapeutic framework that prioritizes early intervention during the clinically silent yet biologically active prodromal stage, when targeted modulation of the HSPB1 chaperone interactome and remodeling neural homeostasis may forestall neurodegeneration. This therapeutic paradigm shift from symptomatic management to preclinical neuroprotection underscores the imperative for precision medicine approaches in future CMT intervention. Full article

Biallelic variants in NDUFS6, encoding an accessory subunit of mitochondrial complex I, were initially associated with lethal neonatal mitochondrial encephalopathy and Leigh syndrome. Recent studies have demonstrated that NDUFS6 variants can also cause childhood- or adolescent-onset axonal neuropathy and Charcot–Marie–Tooth (CMT)-like phenotypes, indicating marked clinical heterogeneity. Here, we report a patient with a novel homozygous truncating NDUFS6 variant presenting with a neuropathy-predominant phenotype accompanied by epilepsy, in the absence of neonatal metabolic decompensation. The patient presented with childhood-onset progressive gait abnormality, pes cavus deformity, distal weakness requiring Achilles tendon-release surgery, pyramidal signs, urinary incontinence, and focal epileptiform EEG findings. Brain MRI showed bilateral lenticular nucleus abnormalities. Whole-exome sequencing identified a novel homozygous NDUFS6 nonsense variant (c.130C>T, p.Gln44*). While neuropathy has previously been reported primarily in association with the recurrent splice-site variant c.309+5G>A, our findings demonstrate that truncating NDUFS6 mutations can also underlie a neuropathy-predominant phenotype. Together with previously published cases, our findings support a phenotypic heterogeneity ranging from lethal encephalopathy to neuropathy and reinforce the role of NDUFS6 as a disease-causing gene for inherited peripheral neuropathy. These data support inclusion of NDUFS6 among established neuropathy and Charcot–Marie–Tooth genes. Full article

Hereditary polyneuropathies represent a genetically and clinically heterogeneous group of disorders affecting the peripheral nervous system, characterized by progressive motor, sensory, and autonomic impairment. Advances in molecular genetics have identified key causative genes, including PMP22, MPZ, MFN2, TTR, EGR2, and CX32 (GJB1), which are implicated in Charcot–Marie–Tooth disease, Dejerine–Sottas syndrome, and related neuropathies. These conditions display substantial allelic and locus heterogeneity. Pathogenetically, mechanisms involve impaired myelin maintenance, disrupted axonal transport, mitochondrial dysfunction, and aberrant Schwann cell biology. Despite these insights, therapeutic options remain limited, and there is a pressing need to translate genetic findings into effective interventions. This review aims to provide a comprehensive synthesis of current knowledge compiling all known mutations resulting in hereditary polyneuropathies. In addition, it underscores the molecular pathomechanisms of hereditary polyneuropathies and evaluates emerging therapeutic strategies, including adeno-associated virus mediated RNA interference, CRISPR-based gene editing, antisense oligonucleotide therapy, and small-molecule modulators of axonal degeneration. Furthermore, the integration of precision diagnostics, such as next-generation sequencing and functional genomic approaches, is discussed in the context of personalized disease management. Collectively, this review underscores the need for patient-centered approaches in advancing care for individuals with hereditary polyneuropathies. Full article

Background/Objectives: Charcot-Marie-Tooth (CMT) disease, the most common hereditary peripheral neuropathy, often causes cavovarus foot deformity in children. Surgical interventions to correct deformity or improve function can involve either primary fusion or reconstruction. However, the optimal surgical approach remains contested. This systematic review aims to present and evaluate existing data on both fusion and reconstruction surgical interventions in treating pediatric CMT cavus foot. Methods: A PRISMA-guided search of five electronic databases was conducted (from inception to 17 February 2025). Studies were eligible if they reported surgical outcomes for CMT pediatric patients ($\le$18 years) with cavovarus foot treated by primary fusion or reconstruction. Titles, abstracts and full texts were screened by four independent reviewers, and data were extracted on patient demographics, procedures, follow-up, functional scores, radiographic correction and complications. Results: Fourteen studies met inclusion criteria, encompassing 169 patients and 276 feet, with a mean age at surgery of ~13.5 years. Nine studies evaluated joint-sparing reconstruction, three assessed primary fusion, and two combined both reconstruction and fusion. Both interventions yielded improved outcomes post-operatively. Reconstruction generally produced high patient satisfaction and near-normal radiographic parameters but carried recurrence or reoperation rates of 10–40%. Fusion provided durable correction of rigid deformities but was associated with nonunion, adjacent joint arthritis and higher revision rates. Conclusions: Joint-sparing reconstruction is an effective first-line approach for flexible cavovarus deformities in pediatric CMT patients, while fusion should be reserved for severe, rigid or recurrent cases. A patient-specific staged approach is recommended, and higher-quality comparative studies are needed to refine surgical decision-making. Full article

The increasing prevalence of neurological disorders highlights the need for disease animal models to elucidate the underlying biomolecular and cellular mechanisms of disease and to facilitate studies aimed at developing effective treatments. The fruit fly Drosophila melanogaster, at both larval and adult stages, can serve as an effective model for different human-relevant neurological diseases. Larvae are particularly suited for studying peripheral nervous system disorders, such as Charcot–Marie–Tooth and amyotrophic lateral sclerosis, while adults enable investigations of higher-order cognitive functions and age-related conditions, including Parkinson’s disease and depression-like behaviours. Combining larval and adult models offers a complementary framework to dissect the biomolecular pathways of neurological disorders and accelerate preclinical research. Full article

Background: Charcot–Marie–Tooth disease (CMTd) is the most prevalent inherited peripheral neuropathy, often associated with foot deformities and gait and balance impairments. While the structural characteristics of the foot have been extensively investigated, limited data are available regarding the features of the plantar fascia in individuals with CMTd. Aim: To investigate the ultrasound (US) structural characteristics of the plantar fascia in subjects with CMTd and to explore their relations with disease severity and functional outcomes, encompassing lower extremity function, gait, and balance. Methods: A total of 26 individuals with confirmed CMTd underwent clinical and functional assessments. Bilateral ultrasound examination of the plantar fascia was performed to assess thickness, echogenicity, fibrillar pattern, and inflammatory signs (as assessed by US Power Doppler). Correlations between ultrasound findings, clinical data, and functional measures were also evaluated. Results: No pathological increase in plantar fascia thickness was observed, although a significant side-to-side difference was noted (p = 0.031) on ultrasound (US) imaging. No inflammatory signs were also detected. Significant associations were found between fascial alterations and age (p = 0.024), disease severity (CMTES, p = 0.014), and functional performance (10 MWT p = 0.017; SPPB p = 0.039). Conclusions: In individuals with CMT, plantar fascia abnormalities likely reflect chronic structural degeneration rather than acute inflammation. These changes are more evident with an increase in age, disease progression, and functional decline, suggesting the role of US imaging as a valuable tool for clinical and therapeutic strategies. Full article

Charcot–Marie–Tooth disease type 1A (CMT1A) is a hereditary condition caused by the duplication of the PMP22 gene. Overexpression of peripheral myelin protein 22 in Schwann cells leads to myelin sheath defects and axonal loss. We have produced a cell model to facilitate studies of the molecular mechanisms involved in PMP22 accumulation and clearance. Our model is a stably transfected, clonal, immortalised human Schwann cell line with overexpressed levels of PMP22 fusion protein. A control-transfected cell line (vector lacking PMP22) was also produced. PMP22-transfected cells had reduced levels of mitosis, with the PMP22 fusion protein concentrated in punctate aggregates in the cytoplasm and expressed at the plasma membranes, which were often irregular and spindly. In contrast, control cells (control-transfected and parent cell lines) generally had smooth and regular plasma membrane morphology. Culturing in the presence of NRG1 and forskolin lead to upregulation of markers of myelination potential in the control cells. These markers were more variable in the cells stably transfected with PMP22, including decreased levels of transcripts of SOX10, JUN, S100B and NGFR, but increased levels of MPZ and EGR2 compared to controls. Using proximity-dependent biotin identification (BioID2), several hundred proteins were identified in the proximity of the overexpressed PMP22, of which 291 significant proteins were only detected in the proximity of PMP22 and not in that of control pull-downs. Among the most significantly enriched PMP22-interacting proteins were integrins alpha-2 (ITGA2) and alpha-7 (ITGA7), which play a role in myelination via their interactions with the extracellular matrix. The presence of ITGA2 in just the PMP22-transfected fraction was confirmed by western blot. Some of the proteins were associated with several enriched molecular pathways, including molecular transport and protein trafficking, and may represent potential therapeutic targets for CMT1A by promoting the degradation and enhanced trafficking of PMP22. Full article

Neurological disorders significantly affect ocular surface homeostasis, influencing parameters such as blink rate (BR), tear production, corneal nerve density, and sensitivity. This review summarizes recent findings on ocular surface alterations associated with neurological diseases, including Alzheimer’s disease (AD), Parkinson’s disease (PD), Guillain-Barré syndrome (GBS), trigeminal neuralgia (TN), multiple sclerosis (MS), and Charcot–Marie–Tooth disease (CMT). Notably, ocular manifestations such as reduced BR, decreased tear break-up time (TBUT), impaired tear secretion, and corneal nerve fiber loss are consistently reported. In AD, elevated tear amyloid-beta and tau proteins emerge as promising biomarkers for early disease detection. PD patients frequently experience dry eye symptoms attributed to reduced BR and tear film instability. GBS is linked to lagophthalmos and corneal nerve impairment, potentially leading to severe ocular surface damage. TN demonstrates bilateral ocular surface dysfunction despite unilateral neuropathic symptoms. MS is associated with significant ocular surface alterations, reflecting broader neuroinflammatory and autonomic disturbances. Similarly, CMT patients show reduced corneal sensitivity and tear production, underscoring the systemic nature of neurological impacts. Awareness of these ocular manifestations is essential for improving patient care and guiding future research into ocular biomarkers and targeted therapies. Full article