BACKGROUND:The therapeutic landscape of generalised myasthenia gravis (gMG) has evolved substantially with the approval of targeted immunotherapies, including complement C5 inhibitors (C5-I) and neonatal Fc receptor inhibitors (FcRn-I). While pivotal trials have demonstrated marked efficacy in defined subgroups, real-world experience reveals more heterogeneous outcomes and raises questions about optimal patient selection, therapy sequencing and integration into clinical practice. In Germany and Austria, early access following regulatory approval has facilitated clinical experience over recent years. This expert opinion paper aims to combine current evidence with clinical experience to guide the use of C5-I and FcRn-I in everyday care. METHODS:A panel of 18 neurologists from Germany and Austria, including two paediatric neurologists, evaluated study data and real-world experiences. Through structured discussion and a consensus process, they developed evidence- and experience-based recommendations on integrating targeted immunotherapies into existing treatment algorithms. RESULTS:The panel provides practical recommendations for managing (highly) active gMG in adults, focusing on C5-I (eculizumab, ravulizumab, zilucoplan) and FcRn-I (efgartigimod, rozanolixizumab). The statements cover initiation criteria, sequencing and switching within and between drug classes and transitions to intensified immunomodulatory therapies (rituximab, apheresis, intravenous or subcutaneous immunoglobulin), as well as special considerations for juvenile MG. CONCLUSIONS:This expert statement provides a practice-oriented framework integrating current evidence and clinical experience to support individualised therapeutic decision-making in gMG.

OBJECTIVE:Thioredoxin-interacting protein (TXNIP) is a protein involved in redox metabolism, but also a key regulator of glucose and lipid metabolism in preclinical models. To date, four patients with biallelic loss-of-function variants in TXNIP have been described, presenting with lactic acidosis and variable hypoglycemia, hepatomegaly, developmental delay and seizures. However, the role of TXNIP in human metabolism and its mechanistic effects across different organs are not fully understood. METHODS:We clinically, biochemically and genetically characterized a cohort of six additional individuals with biallelic pathogenic variants in TXNIP. Organ specimens from patients and mice were analyzed by gene expression, histology, and lipidomic and proteomic profiling. RESULTS:We confirmed lactic acidosis as the main clinical sign and added adult-onset cardiomyopathy, skeletal muscle weakness, and dyslipidemia to the extended disease spectrum. Heart, liver and muscle patient specimens showed pathological lipid accumulation, and mechanistic studies uncovered increased fatty acid synthesis markers and complex rearrangements of the lipidome and proteome. In Txnip-deficient mice, restricting dietary carbohydrates partially rescued fatty acid synthesis markers and lipid storage in the heart but led to dyslipidemia. CONCLUSIONS:Our studies show that TXNIP is an important metabolic modifier in cardiac and skeletal muscle as well as in lipoprotein metabolism and that biallelic pathogenic variants in TXNIP lead to a pleiotropic disease affecting cellular lipid metabolism in multiple organ systems, with potentially fatal adult-onset cardiomyopathy.

Next-generation enzyme replacement therapies (ERTs) for late-onset Pompe disease (LOPD), including avalglucosidase alfa and cipaglucosidase alfa with miglustat, have been developed to improve muscle targeting and enzyme stability. Real-world evidence on therapy switching between ERT preparations remains limited. A prospective, observational, multicenter cohort study was conducted across German neuromuscular centers. Adults with genetically confirmed LOPD who transitioned to avalglucosidase alfa (Aval) or cipaglucosidase alfa with miglustat (Cipa/Mig) between August/2022 and September/2024 were included. Clinical data were extracted from medical records using a standardized case report form. Following EPOC recommendations, data captured comprised six-minute walk test (6MWT), ten-meter walk test (10MWT), Rasch-built Pompe-specific Activity scale (R-PAct), upright and supine forced vital capacity (FVC), maximal inspiratory/expiratory pressure (MIP/MEP), and maximal voluntary ventilation (MVV). Data were analyzed descriptively and using linear mixed-effects models. Paired comparisons between baseline and 12 months were performed as a secondary analysis in patients with available data. Thirty-nine patients (43 switches; alglucosidase alfa (AlGlu) → Aval n = 32, AlGlu → Cipa/Mig n = 7) were included; four double switches were analyzed under AlGlu → Aval. Main reasons for switching were patient request (42

Background Single-cell and single-nucleus RNA sequencing have transformed our understanding of human skeletal muscle biology, yet reproducibility and cross-study comparison remain limited by the lack of a unified reference framework and consistent cell-type annotation. Methods We systematically searched for scRNA-seq and snRNA-seq datasets from adult human skeletal muscle. Seven eligible studies were retrieved and harmonised. We benchmarked multiple integration strategies to construct a joint reference atlas and derived modality-aware marker panels. Selected findings were validated by immunofluorescence in muscle biopsies. Findings We generated a harmonised atlas comprising 122,000 cells and 630,000 nuclei from 88 healthy individuals and resolved 17 major skeletal muscle cell populations, spanning mononuclear compartments and multinucleated myofibers. Cross-modality analysis identified tissue- and modality-aware marker panels and nominated both established and previously unrecognised markers. NOVA1 emerged as a selective marker of fibro-adipogenic progenitors and was validated at the transcript and protein levels. Focusing on myonuclei, pseudotime modelling reconstructed differentiation trajectories from quiescent muscle stem cells to mature type I and type II myofibers and revealed lineage-specific programs, including transient activation of protocadherin-γ genes during type I myofiber differentiation. We further provide an interactive web application for marker-based cell-type prediction using the reference atlas. Interpretation This integrated reference atlas and accompanying annotation tool establish a standardised framework for human muscle transcriptomics, promoting consistent cell-type assignment and providing a baseline for future studies of muscle development, ageing, and disease. Funding Else Kröner-Fresenius-Stiftung and the German Research Foundation.

Late-onset Pompe disease (LOPD) is a rare inherited disorder caused by deficiency of the lysosomal enzyme acid α-glucosidase (GAA), leading to an accumulation of lysosomal glycogen in tissues, profoundly affecting muscles. Patients with LOPD typically have some residual GAA activity but experience progressive skeletal muscle dysfunction resulting in muscle weakness and respiratory failure. Enzyme replacement therapy (ERT) with alglucosidase alfa, a recombinant human GAA (rhGAA), was the first disease-specific therapy for Pompe disease. Despite efficacy in the first years of use, many patients receiving alglucosidase alfa experience a decline in function over time. This may reflect the inherent challenges associated with rhGAA ERT, such as enzyme inactivation at the near-neutral pH of blood, inefficient target cell uptake, and a necessity for complete lysosomal processing once inside target cells. Cipaglucosidase alfa, a second-generation rhGAA, aims to address these challenges through natural enrichment with bis-mannose-6-phosphate-containing N -glycans to enhance cellular uptake while retaining capacity for complete postdelivery processing. Co-administration of cipaglucosidase alfa with the small molecule stabilizer miglustat (N-butyldeoxynojirimycin) enhances cipaglucosidase alfa stability in the bloodstream after infusion. We discuss published and new preclinical and clinical data on the efficacy and safety of miglustat in combination with cipaglucosidase alfa for treating LOPD. Studies in Pompe mouse models and patients with Pompe disease showed that stabilization by miglustat improved cipaglucosidase alfa exposure and availability for uptake into target tissues and was associated with improved functional outcomes and biomarker levels compared with cipaglucosidase alfa alone. In patients with Pompe disease, the once every 2 weeks dosing regimen of miglustat was well tolerated, with a low frequency of miglustat-related gastrointestinal events compared with daily miglustat regimens at higher doses used in the treatment of other diseases. Trial registration : New data are reported for NCT02675465 (ATB200-02), NCT03729362 (PROPEL), and NCT04138277 (PROPEL open-label extension, ATB200-07); all registered at ClinicalTrials.gov ( https://clinicaltrials.gov ).

Background Myotonic Dystrophy Type 1 (DM1), the most common genetic neuromuscular disorder in adults, poses significant challenges for drug development due to its multisystem nature and high clinical variability in symptoms and disease progression. With a growing number of therapies entering clinical trials, this study addresses the urgent need for biomarkers that can serve as surrogate endpoints. Methods We profiled 437 serum samples from adult DM1 patients collected at two timepoints of the OPTIMISTIC trial using bottom-up mass spectrometry with data-independent acquisition. Associations between protein expression, the disease-causing CTG-repeat and 25 clinical outcome measures were studied using linear mixed-effect models. All key study findings were validated in an independent cohort of 69 DM1 patients and 10 healthy controls. Results Of the 259 identified proteins, 161 showed significant associations with the CTG-repeat length (FDR < 5%). Hypogammaglobulinemia was confirmed and shown to be worse in severely affected patients. A strong proteomic signature was associated with clinical measures of functional capacity, with the 6-Minute Walk Test showing the strongest signal (70 associations, FDR < 5%). These novel associations reveal a compelling link between chronic inflammation and reduced functional capacity. A machine learning algorithm identified a minimal set of 13 proteins robustly reflecting both the underlying genetic defect and functional capacity. Conclusions DM1 induces a broad disease fingerprint in the serum proteome, predominantly affecting proteins of the immune system. A carefully selected panel of proteins showed the greatest potential to meet the statistical criteria required for surrogate endpoints in clinical trials.

BACKGROUND AND OBJECTIVES:Delayed grip relaxation is a common symptom of myotonic dystrophy type 1 (DM1), differing from other muscle diseases. Preclinical studies suggest myotonia may reverse quickly with targeted treatment and video hand opening time (vHOT) could be a straightforward method for assessing myotonia in multicenter trials, but few studies have evaluated vHOT in large DM1 cohorts. This study aimed to evaluate how vHOT performs and relates to other disease aspects in a large, well-characterized DM1 population. METHODS:The vHOT was conducted in the END-DM1 natural history study across 22 international sites, including adult DM1 patients with a genetic or research criteria diagnosis. The primary outcome involved video-recorded hand opening after a maximum 3-second grip, performed twice at each study visit with 5-minute rest between trials, and blinded scoring at a central site. Muscle strength and function were assessed by myometry, timed functional tests, and patient-reported outcomes. Procedures were repeated after 1 year for a subset of participants. Wilcoxon signed-rank was used to evaluate differences and Spearman correlation for associations. RESULTS:A total of 591 patients with DM1 (mean age 43.7 ± 12.9 years, 57% female) were included, showing a broad spectrum of vHOT severity (median 3.9 seconds, interquartile range 1.8-7.9 seconds). At a single study visit, there were no systematic difference and good agreement between trials (mean difference 0.1 ± 3.7 seconds [p = 0.05], intraclass correlation coefficient 0.84 [95% CI 0.81-0.86]). vHOT correlated relatively weak with self-reported myotonia (ρ = 0.39), and even lower for other measures of muscle impairments such as grip strength (ρ = -0.21) or 9-hole pegboard (ρ = 0.12). 270 patients completed the 1-year follow-up, with vHOT showing no progression (mean difference 0.4 ± 4.7 seconds, p = 0.34). DISCUSSION:The vHOT procedure was performed successfully in a large international study, with grip relaxation delay varying from minimal to highly prolonged in an unselected cohort. The weak correlation with grip weakness supports the notion that myotonia and weakness are mechanistically distinct. Study limitations include underrepresentation of congenital DM1 and lack of other myotonia measures (e.g., handgrip relaxation myometry). It seems that vHOT is not suitable to assess disease progression, but stability over 1 year may support its use to assess improvement. TRIAL REGISTRATION INFORMATION:The END-DM1 observational study is registered with number NCT03981575.

Late-onset Pompe disease (LOPD) is a rare neuromuscular disorder, where delays in diagnosis can result in inconsistent patient management and suboptimal use of effective treatments, thereby increasing patient burden. We conducted an exploratory, cross-sectional survey of 20 adults with LOPD in the UK and USA, recruited via patient advocacy groups and vetted databases. Our results showed that patients with LOPD experienced substantial delays from symptom onset to diagnosis. Interactions with healthcare professionals (HCPs) were inconsistent, and LOPD awareness among HCPs was insufficient. Patients were generally satisfied with their treatment, with 90% of patients reporting mild to no discomfort with enzyme replacement therapy or other treatments. However, 60% of patients implemented various nonpharmacological therapies to manage pain or other aspects of LOPD. These exploratory findings highlight persistent gaps in diagnosis and care, emphasizing the need for improved HCP education and integrated support services.

Abstract Myotonic dystrophy type 1 is caused by the expression of expanded CTG repeats in the DMPK gene and the resulting loss of function of MBNL protein. Affected skeletal muscle displays abundant centrally located nuclei despite limited immune-cell–associated fibre necrosis, complicating interpretation of muscle damage and remodelling mechanisms. Here we show that muscle stem cells are activated and fuse with existing muscle fibres in myotonic dystrophy type 1. Single-nucleus transcriptomics in patient’s muscle identifies increased activated muscle stem cells and distinct myonuclear populations exhibiting transitional transcriptional states, including muscle stem cell associated markers and elevated DMPK expression. Myofibre-specific MBNL knockdown mouse models demonstrate that muscle stem cell fusion contributes to central nucleation, whereas their deletion does not improve myotonia or muscle strength. Together, these findings indicate that loss of MBNL function in muscle drives myonuclear accretion through stem cell-mediated fusion, giving rise to myonuclei with immature states in myotonic dystrophy type 1.

BackgroundX-linked myotubular myopathy (XLMTM) and autosomal dominant centronuclear myopathy (ADCNM) are rare neuromuscular disorders characterized by severe weakness and respiratory impairment and have recently been the focus of therapeutic development. Robust baseline data are essential to understand disease trajectories and enable trial readiness. We present baseline clinical, functional, and biomarker findings from the terminated Unite-CNM trial (NCT04033159), a basket study of the antisense oligonucleotide DYN101, designed to modulate DNM2 expression in adolescents and adults with XLMTM or ADCNM.MethodsScreening and baseline evaluations included medical history, patient-reported outcomes, quantitative muscle strength and motor function, respiratory testing, muscle ultrasound and histology, and biomarker analyses (DNM2 protein, creatinine, creatine kinase, cystatin C, myostatin, and microRNAs) in plasma and muscle.ResultsTwenty-six patients were screened (15 DNM2, 11 MTM1); 14 entered the study. Patient-reported measures highlighted swallowing challenges and variable personal goals. Baseline respiratory impairment was variable in DNM2 and female MTM1 patients but consistently reduced in males with MTM1 (FVC% and FEV1% stable over follow-up to 78 weeks). MFM32 scores were similar across genotypes and sexes, while Myogrip strength was reduced versus age norms yet stable longitudinally. Muscle pathology was comparable across groups. Biomarker analyses showed altered DNM2 protein, reduced myostatin, and specific abnormalities in creatinine, creatine kinase, cystatin C, and microRNAs.ConclusionThis dataset provides valuable phenotypic, functional, and biomarker characterization of adult XLMTM and ADCNM, emphasizes the importance of baseline data for ultrarare disease trials, and highlights the need for protocol flexibility in response to safety signals and disruptions (e.g. COVID-19).

BACKGROUND:Losmapimod is an orally administered small molecule and selective p38α/β mitogen-activated protein kinase (MAPK) inhibitor able to reduce aberrant expression of DUX4 in vitro and thereby potentially slowing disease progression in patients with facioscapulohumeral muscular dystrophy (FSHD). OBJECTIVE:This global, randomized, placebo-controlled, double-blind phase 3 study in patients with FSHD1 and FSHD2 examined the efficacy and safety of losmapimod over a 48-week treatment period compared to placebo (NCT05397470, EUDRACT 2022-000389-16). METHODS:The primary endpoint was change in quantification of reachable workspace (RWS) expressed as relative surface area (RSA). Other endpoints included measures of muscle composition (fat content and lean muscle) using magnetic resonance imaging (MRI), muscle strength using quantitative dynamometry, and quality of life measures. RESULTS:130 participants received losmapimod and 130 participants received placebo, with 252 participants completing the 48-week treatment period. There were no statistically significant differences between groups in change in RSA and all secondary efficacy endpoints from baseline to Week 48. Losmapimod treatment was well-tolerated, and most adverse events were mild. CONCLUSIONS:Losmapimod was generally well tolerated with a favorable safety profile at a dose of 15 mg twice daily. Although none of the efficacy endpoints were met, study design and data from the study may inform future studies of FSHD therapies.

Abstract Background Myasthenia gravis has a variable disease course. Early identification of patients with a highly active disease is crucial to prevent myasthenic exacerbations and crisis, necessitating more aggressive immunotherapy. However, no biomarkers currently exist to identify patients at risk for highly active disease course. Objective The PROGNO-MG study aims to identify blood-based biomarker signatures associated with a highly active disease course in immunotherapy-naïve patients with acetylcholine-receptor-antibody positive (AChR+) generalized Myasthenia gravis (gMG). Methods This is an investigator-initiated prospective, multicentric, observational study. Seventy newly diagnosed immunotherapy-naïve AChR+ gMG patients will be enrolled and followed up for 24 months. Blood samples and clinical data will be collected biannually. Biomarkers (calprotectin, neurofilament light chain, ITIH3, complement activation, kappa free light chains, and exploratory proteome-analyses and immune cell phenotyping) will be measured and their association with clinical outcomes will be evaluated. Perspective The results will provide evidence for prognostic biomarkers, supporting risk stratification and early individualized treatment for AChR+ gMG patients. Trial registration The study is registered in the German clinical trial register (DRKS00035457).