JEWELFISH: 24-month results from an open-label study in non-treatment-naïve patients with SMA receiving treatment with risdiplam.

Risdiplam is a once-daily oral, survival of motor neuron 2 (SMN2) splicing modifier approved for the treatment of spinal muscular atrophy (SMA). JEWELFISH (NCT03032172) investigated the safety, tolerability, pharmacokinetics (PK), and PK/pharmacodynamic (PD) relationship of risdiplam in non-treatment-naïve patients with SMA. JEWELFISH enrolled adult and pediatric patients (N = 174) with confirmed diagnosis of 5q-autosomal recessive SMA who had previously received treatment with nusinersen (n = 76), onasemnogene abeparvovec (n = 14), olesoxime (n = 71), or were enrolled in the MOONFISH study (NCT02240355) of the splicing modifier RG7800 (n = 13). JEWELFISH was an open-label study with all participants scheduled to receive risdiplam. The most common adverse event (AE) was pyrexia (42 patients, 24%) and the most common serious AE (SAE) was pneumonia (5 patients, 3%). The rate of AEs and SAEs decreased by > 50% from the first to the second year of treatment, and there were no treatment-related AEs that led to withdrawal from treatment. An increase in SMN protein in blood was observed following risdiplam treatment and sustained over 24 months of treatment irrespective of previous treatment. Exploratory efficacy assessments of motor function showed an overall stabilization in mean total scores as assessed by the 32-item Motor Function Measure, Hammersmith Functional Motor Scale-Expanded, and Revised Upper Limb Module. The safety profile of risdiplam in JEWELFISH was consistent with previous clinical trials of risdiplam in treatment-naïve patients. Exploratory efficacy outcomes are reported but it should be noted that the main aim of JEWELFISH was to assess safety and PK/PD, and the study was not designed for efficacy analysis. TRIAL REGISTRATION: The study was registered (NCT03032172) on ClinicalTrials.gov on January 24, 2017; First patient enrolled: March 3, 2017.

Dysregulated iron homeostasis in dystrophin-deficient cardiomyocytes: correction by gene editing and pharmacological treatment.

AIMS: Duchenne muscular dystrophy (DMD)-associated cardiomyopathy is a serious life-threatening complication, the mechanisms of which have not been fully established, and therefore no effective treatment is currently available. The purpose of the study was to identify new molecular signatures of the cardiomyopathy development in DMD. METHODS AND RESULTS: For modelling of DMD-associated cardiomyopathy, we prepared three pairs of isogenic control and dystrophin-deficient human induced pluripotent stem cell (hiPSC) lines. Two isogenic hiPSC lines were obtained by CRISPR/Cas9-mediated deletion of DMD exon 50 in unaffected cells generated from healthy donor and then differentiated into cardiomyocytes (hiPSC-CM). The latter were subjected to global transcriptomic and proteomic analyses followed by more in-depth investigation of selected pathway and pharmacological modulation of observed defects. Proteomic analysis indicated a decrease in the level of mitoNEET protein in dystrophin-deficient hiPSC-CM, suggesting alteration in iron metabolism. Further experiments demonstrated increased labile iron pool both in the cytoplasm and mitochondria, a decrease in ferroportin level and an increase in both ferritin and transferrin receptor in DMD hiPSC-CM. Importantly, CRISPR/Cas9-mediated correction of the mutation in the patient-derived hiPSC reversed the observed changes in iron metabolism and restored normal iron levels in cardiomyocytes. Moreover, treatment of DMD hiPSC-CM with deferoxamine (DFO, iron chelator) or pioglitazone (mitoNEET stabilizing compound) decreased the level of reactive oxygen species in DMD hiPSC-CM. CONCLUSION: To our knowledge, this study demonstrated for the first time impaired iron metabolism in human DMD cardiomyocytes, and potential reversal of this effect by correction of DMD mutation or pharmacological treatment. This implies that iron overload-regulating compounds may serve as novel therapeutic agents in DMD-associated cardiomyopathy.

Differences in diffusion tensor imaging parameters of brain white matter tracts between patients with myotonic dystrophy type 1 and type 2 - a retrospective single-centre study.

INTRODUCTION: The main aim of our study was to compare diffusion tensor imaging (DTI) parameters in patients with myotonic dystrophy types 1 and 2 (DM1 and DM2). CLINICAL RATIONALE FOR THE STUDY: To ascertain whether DTI could be used to assess the integrity of white matter tracts in the brain and identify any abnormalities or disruptions in connectivity between different brain regions in patients with DM. By providing a more detailed understanding of the structural changes in the brain associated with DM, could DTI potentially be used to develop more effective treatments for the cognitive and neurological symptoms of the disorder? MATERIAL AND METHODS: We retrospectively compared MRI scans of 19 patients with DM1 to those of 23 healthy, matched controls, and of 16 patients with DM2 to those of 20 healthy, matched controls, and finally compared the DM1 and DM2 samples. Fraction anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD), and axial diffusivity (AD) values were assessed using Tract Based Spatial Statistics (TBSS). RESULTS: In patients with DM1, a statistically significant decrease in the values of the FA parameter was revealed in 45/48 white matter tracts compared to patients with DM2. There was no statistically significant decrease in the values of the FA parameter in patients with DM2 compared to DM1. The values of MD and RD were significantly higher in 47 tracts in DM1 patients compared to DM2 patients. AD values were significantly higher in all 48 tracts in DM1 patients compared to DM2 patients. There were no tracts with increased MD, AD, or RD values in DM2 patients compared to DM1. CONCLUSIONS: Our results indicate diffuse disintegration of white matter pathways in DM patients, especially in the DM1 group. The damage to all types of fibres (association, commissural, and projection) may explain the diversity of clinical symptoms, which were more severe in the DM1 group of patients than in the DM2 group. CLINICAL IMPLICATIONS: DTI in patients with DM may help us to understand the neural mechanisms underlying brain involvement during the disease. In future, it may help to identify biomarkers for disease progression and treatment response.

Analysis of muscle magnetic resonance imaging of a large cohort of patient with VCP-mediated disease reveals characteristic features useful for diagnosis.

BACKGROUND: The diagnosis of patients with mutations in the VCP gene can be complicated due to their broad phenotypic spectrum including myopathy, motor neuron disease and peripheral neuropathy. Muscle MRI guides the diagnosis in neuromuscular diseases (NMDs); however, comprehensive muscle MRI features for VCP patients have not been reported so far. METHODS: We collected muscle MRIs of 80 of the 255 patients who participated in the "VCP International Study" and reviewed the T1-weighted (T1w) and short tau inversion recovery (STIR) sequences. We identified a series of potential diagnostic MRI based characteristics useful for the diagnosis of VCP disease and validated them in 1089 MRIs from patients with other genetically confirmed NMDs. RESULTS: Fat replacement of at least one muscle was identified in all symptomatic patients. The most common finding was the existence of patchy areas of fat replacement. Although there was a wide variability of muscles affected, we observed a common pattern characterized by the involvement of periscapular, paraspinal, gluteal and quadriceps muscles. STIR signal was enhanced in 67% of the patients, either in the muscle itself or in the surrounding fascia. We identified 10 diagnostic characteristics based on the pattern identified that allowed us to distinguish VCP disease from other neuromuscular diseases with high accuracy. CONCLUSIONS: Patients with mutations in the VCP gene had common features on muscle MRI that are helpful for diagnosis purposes, including the presence of patchy fat replacement and a prominent involvement of the periscapular, paraspinal, abdominal and thigh muscles.

Long-term nusinersen treatment across a wide spectrum of spinal muscular atrophy severity: a real-world experience.

BACKGROUND: Spinal muscular atrophy (SMA) is an autosomal recessive disorder caused by a biallelic mutation in the SMN1 gene, resulting in progressive muscle weakness and atrophy. Nusinersen is the first disease-modifying drug for all SMA types. We report on effectiveness and safety data from 120 adults and older children with SMA types 1c-3 treated with nusinersen. METHODS: Patients were evaluated with the Hammersmith Functional Motor Scale Expanded (HFMSE; n = 73) or the Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders (CHOP-INTEND; n = 47). Additionally, the Revised Upper Limb Module (RULM) and 6-minute walk test (6MWT) were used in a subset of patients. Patients were followed for up to 30 months of nusinersen treatment (mean, SD; 23, 14 months). Subjective treatment outcomes were evaluated with the Patients Global Impression-Improvement (PGI-I) scale used in all patients or caregivers at each follow-up visit. RESULTS: An increase in the mean HFMSE score was noted at month 14 (T14) (3.9 points, p < 0.001) and month 30 (T30) (5.1 points, p < 0.001). The mean RULM score increased by 0.79 points at T14 (p = 0.001) and 1.96 points (p < 0.001) at month 30 (T30). The mean CHOP-INTEND increased by 3.6 points at T14 (p < 0.001) and 5.6 points at month 26 (p < 0.001). The mean 6MWT improved by 16.6 m at T14 and 27 m at T30 vs. baseline. A clinically meaningful improvement in HFMSE (≥ 3 points) was seen in 62% of patients at T14, and in 71% at T30; in CHOP INTEND (≥ 4 points), in 58% of patients at T14 and in 80% at T30; in RULM (≥ 2 points), in 26.6% of patients at T14 and in 43.5% at T30; and in 6MWT (≥ 30-meter increase), in 26% of patients at T14 and in 50% at T30. Improved PGI-I scores were reported for 75% of patients at T14 and 85% at T30; none of the patients reporting worsening at T30. Adverse events were mild and related to lumbar puncture. CONCLUSIONS: In our study, nusinersen led to continuous functional improvement over 30-month follow-up and was well tolerated by adults and older children with a wide spectrum of SMA severity.

Real World Evidence on the Effectiveness of Nusinersen within the National Program to Treat Spinal Muscular Atrophy in Poland.

BACKGROUND: Spinal muscular atrophy (SMA) is a debilitating neuromuscular disease resulting in children's mortality and disability. Nusinersen is available to all SMA patients in Poland since 2019. AIM: To compare mortality or disease progression to mechanical ventilation in two patient cohorts before and after the program's introduction. Additionally, to describe the patient population treated with nusinersen and costs incurred by the public payer. METHODS: We used the National Health Fund (NHF) database to identify patients born in either 2014 or 2019, who received at least two health services with an ICD10 G12 diagnosis. Outcomes were time to event: death or first mechanical ventilation. We identified all benefits received by nusinersen-treated patients, between 1 January 2019 and 31 May 2022. RESULTS: Children with SMA born in 2019 had significantly lower mortality in the first years of their lives than children born in 2014. Approximately 875 patients (all age groups) were treated with nusinersen in the analysis period. The cost of causal drugs in this period amounted to €51.4 million. The cost of healthcare benefits amounted to €14.9 million. CONCLUSIONS: The drug program to treat SMA improved patient care in Poland. The NHF database was a reliable source to monitor resource-intensive therapies' costs, demography, and selected patient outcomes.

Efficacy and Safety of Avalglucosidase Alfa in Patients With Late-Onset Pompe Disease After 97 Weeks: A Phase 3 Randomized Clinical Trial.

Importance: In the previously reported Comparative Enzyme Replacement Trial With neoGAA Versus rhGAA (COMET) trial, avalglucosidase alfa treatment for 49 weeks showed clinically meaningful improvements in upright forced vital capacity (FVC) percent predicted and 6-minute walk test (6MWT) compared with alglucosidase alfa. Objective: To report avalglucosidase alfa treatment outcomes during the COMET trial extension. Design, Setting, and Participants: This phase 3 double-blind randomized clinical trial with crossover in the extension period enrolled patients 3 years and older with previously untreated late-onset Pompe disease (LOPD) between November 2, 2016, and February 10, 2021, with primary analysis after 49 weeks. Patients were treated at 55 referral centers in 20 countries. Efficacy outcomes were assessed at 97 weeks and safety outcomes to last follow-up, with data cutoff at February 10, 2021. Data were analyzed from May to June 2021. Interventions: Random assignment (1:1) to receive 20 mg/kg of avalglucosidase alfa or alglucosidase alfa by intravenous infusion every other week for 49 weeks; thereafter, all patients received 20 mg/kg of avalglucosidase alfa every other week. Main Outcomes and Measures: The primary outcome was the least squares (LS) mean change from baseline in FVC percent predicted. Secondary outcomes included the LS mean change from baseline in 6MWT, muscle strength, motor function, quality of life, and disease biomarkers. Safety and tolerability were also assessed. Results: Of 100 participants from the double-blind treatment period, 95 entered the extension period. Of these, 51 (54%) were men, and the mean (range) age was 48.3 (10-79) years. At the start of this study, mean upright FVC percent predicted was similar between treatment arms, and 6MWT distance was greater in the avalglucosidase alfa arm. From baseline to week 97, LS mean (SE) FVC percent predicted increased by 2.65 (1.05) for those who continued avalglucosidase alfa and 0.36 (1.12) for those who switched to avalglucosidase alfa. The LS mean (SE) 6MWT distance increased by 18.60 (12.01) m and 4.56 (12.44) m, respectively. For participants who switched to avalglucosidase alfa, FVC percent predicted remained stable (LS mean [SE] change from week 49 to 97, 0.09 [0.88]) and 6MWT distance improved (LS mean [SE] change from week 49 to 97, 5.33 [10.81] m). Potentially treatment-related adverse events were reported in 29 patients (56.9%) who continued avalglucosidase alfa and in 25 patients (56.8%) who switched. Conclusions and Relevance: In this randomized clinical trial extension, maintenance of positive clinical outcomes was demonstrated for patients continuing avalglucosidase alfa treatment and, to a lesser extent, patients who switched from alglucosidase alfa. No new safety concerns were observed. Trial Registration: ClinicalTrials.gov Identifier: NCT02782741.

Anoctamin-5 related muscle disease: clinical and genetic findings in a large European cohort.

Anoctamin-5 related muscle disease is caused by biallelic pathogenic variants in the anoctamin-5 gene (ANO5) and shows variable clinical phenotypes: limb-girdle muscular dystrophy type 12 (LGMD-R12), distal muscular dystrophy type 3 (MMD3), pseudometabolic myopathy or asymptomatic hyperCKaemia. In this retrospective, observational, multicentre study we gathered a large European cohort of patients with ANO5-related muscle disease to study the clinical and genetic spectrum and genotype-phenotype correlations. We included 234 patients from 212 different families, contributed by 15 centres from 11 European countries. The largest subgroup was LGMD-R12 (52.6%), followed by pseudometabolic myopathy (20.5%), asymptomatic hyperCKaemia (13.7%) and MMD3 (13.2%). In all subgroups, there was a male predominance, except for pseudometabolic myopathy. Median age at symptom onset of all patients was 33 years (range 23-45 years). The most frequent symptoms at onset were myalgia (35.3%) and exercise intolerance (34.1%), while at last clinical evaluation most frequent symptoms and signs were proximal lower limb weakness (56.9%) and atrophy (38.1%), myalgia (45.1%) and atrophy of the medial gastrocnemius muscle (38.4%). Most patients remained ambulatory (79.4%). At last evaluation, 45.9% of patients with LGMD-R12 additionally had distal weakness in the lower limbs and 48.4% of patients with MMD3 also showed proximal lower limb weakness. Age at symptom onset did not differ significantly between males and females. However, males had a higher risk of using walking aids earlier (P = 0.035). No significant association was identified between sportive versus non-sportive lifestyle before symptom onset and age at symptom onset nor any of the motor outcomes. Cardiac and respiratory involvement that would require treatment occurred very rarely. Ninety-nine different pathogenic variants were identified in ANO5 of which 25 were novel. The most frequent variants were c.191dupA (p.Asn64Lysfs*15) (57.7%) and c.2272C>T (p.Arg758Cys) (11.1%). Patients with two loss-of function variants used walking aids at a significantly earlier age (P = 0.037). Patients homozygous for the c.2272C>T variant showed a later use of walking aids compared to patients with other variants (P = 0.043). We conclude that there was no correlation of the clinical phenotype with the specific genetic variants, and that LGMD-R12 and MMD3 predominantly affect males who have a significantly worse motor outcome. Our study provides useful information for clinical follow up of the patients and for the design of clinical trials with novel therapeutic agents.

Two-year efficacy and safety of risdiplam in patients with type 2 or non-ambulant type 3 spinal muscular atrophy (SMA).

Risdiplam is an oral, survival of motor neuron 2 (SMN2) pre-mRNA splicing modifier approved for the treatment of spinal muscular atrophy (SMA). SUNFISH (NCT02908685) Part 2, a Phase 3, randomized, double-blind, placebo-controlled study, investigated the efficacy and safety of risdiplam in type 2 and non­ambulant type 3 SMA. The primary endpoint was met: a significantly greater change from baseline in 32-item Motor Function Measure (MFM32) total score was observed with risdiplam compared with placebo at month 12. After 12 months, all participants received risdiplam while preserving initial treatment blinding. We report 24-month efficacy and safety results in this population. Month 24 exploratory endpoints included change from baseline in MFM32 and safety. MFM­derived results were compared with an external comparator. At month 24 of risdiplam treatment, 32% of patients demonstrated improvement (a change of ≥ 3) from baseline in MFM32 total score; 58% showed stabilization (a change of ≥ 0). Compared with an external comparator, a treatment difference of 3.12 (95% confidence interval [CI] 1.67-4.57) in favor of risdiplam was observed in MFM-derived scores. Overall, gains in motor function at month 12 were maintained or improved upon at month 24. In patients initially receiving placebo, MFM32 remained stable compared with baseline (0.31 [95% CI - 0.65 to 1.28]) after 12 months of risdiplam; 16% of patients improved their score and 59% exhibited stabilization. The safety profile after 24 months was consistent with that observed after 12 months. Risdiplam over 24 months resulted in further improvement or stabilization in motor function, confirming the benefit of longer-term treatment.

Risdiplam in Patients Previously Treated with Other Therapies for Spinal Muscular Atrophy: An Interim Analysis from the JEWELFISH Study.

INTRODUCTION: Risdiplam is a survival of motor neuron 2 (SMN2) splicing modifier for the treatment of patients with spinal muscular atrophy (SMA). The JEWELFISH study (NCT03032172) was designed to assess the safety, tolerability, pharmacokinetics (PK), and pharmacodynamics (PD) of risdiplam in previously treated pediatric and adult patients with types 1-3 SMA. Here, an analysis was performed after all patients had received at least 1 year of treatment with risdiplam. METHODS: Patients with a confirmed diagnosis of 5q-autosomal recessive SMA between the ages of 6 months and 60 years were eligible for enrollment. Patients were previously enrolled in the MOONFISH study (NCT02240355) with splicing modifier RG7800 or treated with olesoxime, nusinersen, or onasemnogene abeparvovec. The primary objectives of the JEWELFISH study were to evaluate the safety and tolerability of risdiplam and investigate the PK after 2 years of treatment. RESULTS: A total of 174 patients enrolled: MOONFISH study (n = 13), olesoxime (n = 71 patients), nusinersen (n = 76), onasemnogene abeparvovec (n = 14). Most patients (78%) had three SMN2 copies. The median age and weight of patients at enrollment was 14.0 years (1-60 years) and 39.1 kg (9.2-108.9 kg), respectively. About 63% of patients aged 2-60 years had a baseline total score of less than 10 on the Hammersmith Functional Motor Scale-Expanded and 83% had scoliosis. The most common adverse event (AE) was upper respiratory tract infection and pyrexia (30 patients each; 17%). Pneumonia (four patients; 2%) was the most frequently reported serious AE (SAE). The rates of AEs and SAEs per 100 patient-years were lower in the second 6-month period compared with the first. An increase in SMN protein was observed in blood after risdiplam treatment and was comparable across all ages and body weight quartiles. CONCLUSIONS: The safety and PD of risdiplam in patients who were previously treated were consistent with those of treatment-naïve patients.

Transient global amnesia - hippocampal lesions in magnetic resonance imaging.

BACKGROUND: Transient global amnesia is a benign syndrome characterized by a sudden onset loss of anterograde amnesia with full recovery. Magnetic resonance of the brain including diffusion-weighted imaging of patients with transient global amnesia revealed the presence of punctate hyperintense signal abnormalities in the hippocampus. OBJECTIVE: Analysis of the presence of hippocampal lesions in brain magnetic resonance imaging in patients with transient global amnesia and the possible influence of additional factors on their appearance. METHODS: In this retrospective, an observational study we assessed brain magnetic resonance imaging in 38 consecutive patients with transient global amnesia. The incidence of brain magnetic resonance imaging lesions was analyzed for the coexisting cardiovascular risk factors and precipitating events. RESULTS: Hippocampal brain magnetic resonance imaging lesions were detected in 47% of patients with transient global amnesia. Of those, 65% had unilateral lesions, 82% were left-sided, and 28% were right-sided. Most lesions were located in the CA1 subfield. The incidence of hypertension in patients with transient global amnesia was higher than in the general population. Stress and exercise preceded the onset of transient global amnesia only in 13% and 16% of patients, respectively. There was no higher incidence of migraine in transient global amnesia patients (13%). CONCLUSIONS: We found that nearly 50% of patients with transient global amnesia had hyperintense hippocampal brain magnetic resonance imaging lesions. In addition to hypertension, individuals with transient global amnesia had similar cardiovascular risk factors as the general population. We did not identify any precipitating events prior to the onset of transient global amnesia.

Randomized Double-Blind Placebo-Controlled Trial of the Corticosteroid-Sparing Effects of Immunoglobulin in Myasthenia Gravis.

BACKGROUND AND OBJECTIVES: Myasthenia gravis (MG) is an autoimmune disease characterized by dysfunction at the neuromuscular junction. Treatment frequently includes corticosteroids (CSs) and IV immunoglobulin (IVIG). This study was conducted to determine whether immune globulin (human), 10% caprylate/chromatography purified (IGIV-C) could facilitate CS dose reduction in CS-dependent patients with MG. METHODS: In this randomized double-blind placebo-controlled trial, CS-dependent patients with MG (Myasthenia Gravis Foundation of America Class II-Iva; AChR+) received a loading dose of 2 g/kg IGIV-C over 2 days (maximum 80 g/d) or placebo at week 0 (baseline). Maintenance doses (1 g/kg IGIV-C or placebo) were administered every 3 weeks through week 36. Tapering of CS was initiated at week 9 and continued through week 36 unless the patient worsened (quantitative MG score ≥4 points from baseline). CS doses were increased (based on the current CS dose) in patients who worsened. Patients were withdrawn if worsening failed to improve within 6 weeks or if a second CS increase was required. The primary efficacy end point (at week 39) was a ≥50% reduction in CS dose. Secondary and safety end points were assessed throughout the study and follow-up (weeks 42 and 45). The study results and full protocol are available at clinicaltrials.gov/ct2/show/NCT02473965. RESULTS: The primary end point (≥50% reduction in CS dose) showed no significant difference between the IGIV-C treatment (60.0% of patients) and placebo (63.3%). There were no significant differences for secondary end points. Safety data indicated that IGIV-C was well tolerated. DISCUSSION: In this study, IGIV-C was not more effective than placebo in reducing daily CS dose. These results suggest that the effects of IGIV-C and CS are not synergistic and may be mechanistically different. TRIAL REGISTRATION INFORMATION: The trial was registered on clinicaltrialsregister.eu (EudraCT #: 2013-005099-17) and clinicaltrials.gov (identifier NCT02473965). CLASSIFICATION OF EVIDENCE: This study provides Class II evidence that IVIG infusions in adult patients with MG do not increase the percentage of patients achieving a ≥50% reduction in corticosteroid dose compared with placebo.

Multisystem presentation of Late Onset Pompe Disease: what every consulting neurologist should know.

INTRODUCTION: Pompe disease is a rare, autosomal recessive, lysosomal disorder caused by deficiency of alpha glucosidase (GAA). It leads to the accumulation of glycogen in body tissues, with severe myopathy and cardiomegaly as a hallmark of the classic infantile form. Non-classical, or late onset, Pompe disease (LOPD) manifests after 12 months of age or in adulthood. MATERIAL AND METHODS: The clinical heterogeneity of LOPD causes delay in diagnosis and pharmacological treatment. In the Polish population, it is still underdiagnosed, and the time from onset to diagnosis remains a cause for concern. CLINICAL IMPLICATIONS: Although typically patients present with proximal muscle weakness, high CK or early respiratory insufficiency, they can also suffer from multiple symptoms from other organs. Patients may present with arrhythmias, vascular abnormalities including aneurysms or dilative arteriopathy, gastric or urinary symptoms, or musculoskeletal pathologies. RESULTS: A high index of suspicion among neurologists consulting internal medicine wards would aid early diagnosis of LOPD, while a multidisciplinary approach with the involvement of other specialists can reduce the risk of complications and improve the prognosis for LOPD patients. Patients who manifest with musculoskeletal and respiratory symptoms are prone to be diagnosed sooner than individuals with non-muscular symptoms, and therefore it is important to raise awareness of other manifestations of this disease.

Role of autoantibody levels as biomarkers in the management of patients with myasthenia gravis: A systematic review and expert appraisal.

BACKGROUND AND PURPOSE: Although myasthenia gravis (MG) is recognized as an immunoglobulin G autoantibody-mediated disease, the relationship between autoantibody levels and disease activity in MG is unclear. We sought to evaluate this landscape through systematically assessing the evidence, testing the impact of predefined variables on any relationship, and augmenting with expert opinion. METHODS: In October 2020, a forum of leading clinicians and researchers in neurology from across Europe (Expert Forum for Rare Autoantibodies in Neurology in Myasthenia Gravis) participated in a series of virtual meetings that took place alongside the conduct of a systematic literature review (SLR). RESULTS: Forty-two studies were identified meeting inclusion criteria. Of these, 10 reported some correlation between a patient's autoantibody level and disease severity. Generally, decreased autoantibody levels (acetylcholine receptor, muscle-specific kinase, and titin) were positively and significantly correlated with improvements in disease severity (Quantitative Myasthenia Gravis score, Myasthenia Gravis Composite score, Myasthenia Gravis Activities of Daily Living score, Myasthenia Gravis Foundation of America classification). Given the limited evidence, testing the impact of predefined variables was not feasible. CONCLUSIONS: This first SLR to assess whether a correlation exists between autoantibody levels and disease activity in patients with MG has indicated a potential positive correlation, which could have clinical implications in guiding treatment decisions. However, in light of the limited and variable evidence, we cannot currently recommend routine clinical use of autoantibody level testing in this context. For now, patient's characteristics, clinical disease course, and laboratory data (e.g., autoantibody status, thymus histology) should inform management, alongside patient-reported outcomes. We highlight the need for future studies to reach more definitive conclusions on this relationship.

Severe congenital myasthenic syndromes caused by agrin mutations affecting secretion by motoneurons.

Congenital myasthenic syndromes (CMS) are predominantly characterized by muscle weakness and fatigability and can be caused by a variety of mutations in genes required for neuromuscular junction formation and maintenance. Among them, AGRN encodes agrin, an essential synaptic protein secreted by motoneurons. We have identified severe CMS patients with uncharacterized p.R1671Q, p.R1698P and p.L1664P mutations in the LG2 domain of agrin. Overexpression in primary motoneurons cultures in vitro and in chick spinal motoneurons in vivo revealed that the mutations modified agrin trafficking, leading to its accumulation in the soma and/or in the axon. Expression of mutant agrins in cultured cells demonstrated accumulation of agrin in the endoplasmic reticulum associated with induction of unfolded protein response (UPR) and impaired secretion in the culture medium. Interestingly, evaluation of the specific activity of individual agrins on AChR cluster formation indicated that when secreted, mutant agrins retained a normal capacity to trigger the formation of AChR clusters. To confirm agrin accumulation and secretion defect, iPS cells were derived from a patient and differentiated into motoneurons. Patient iPS-derived motoneurons accumulated mutant agrin in the soma and increased XBP1 mRNA splicing, suggesting UPR activation. Moreover, co-cultures of patient iPS-derived motoneurons with myotubes confirmed the deficit in agrin secretion and revealed a reduction in motoneuron survival. Altogether, we report the first mutations in AGRN gene that specifically affect agrin secretion by motoneurons. Interestingly, the three patients carrying these mutations were initially suspected of spinal muscular atrophy (SMA). Therefore, in the presence of patients with a clinical presentation of SMA but without mutation in the SMN1 gene, it can be worth to look for mutations in AGRN.

Value of short exercise and short exercise with cooling tests in diagnosis of recessive form of myotonia congenita (Becker disease) - are sex differences important?

INTRODUCTION: In myotonia congenita (MC), activation with exercise or cooling can induce transient changes in compound motor action potential (CMAP) parameters, thus providing a guide to genetic analysis. MATERIAL AND METHODS: We performed the short exercise test (SET) and the short exercise test with cooling (SETC) in 30 patients with genetically confirmed Becker disease (BMC) to estimate their utility in the diagnosis of BMC. RESULTS: Although we observed a significant decrease in CMAP amplitude immediately after maximal voluntary effort in both tests in the whole BMC group, in men this decline was significantly smaller than in women, especially in SET. Clinical implications/future directions: In men with a clinical suspicion of BMC, a small decrease in CMAP amplitude in SET together with a typical decline in SETC does not exclude the diagnosis of BMC. Our results show a sex-specific difference in chloride channel function in BMC, which needs further investigation.