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INTRODUCTION/AIMS: Facioscapulohumeral muscular dystrophy (FSHD) is a slowly progressive muscular dystrophy without approved therapies. In this study we evaluated whether locally acting ACE-083 could safely increase muscle volume and improve functional outcomes in adults with FSHD. METHODS: Participants were at least 18 years old and had FSHD1/FSHD2. Part 1 was open label, ascending dose, assessing safety and tolerability (primary objective). Part 2 was randomized, double-blind for 6 months, evaluating ACE-083240 mg/muscle vs placebo injected bilaterally every 3 weeks in the biceps brachii (BB) or tibialis anterior (TA) muscles, followed by 6 months of open label. Magnetic resonance imaging measures included total muscle volume (TMV; primary objective), fat fraction (FF), and contractile muscle volume (CMV). Functional measures included 6-minute walk test, 10-meter walk/run, and 4-stair climb (TA group), and performance of upper limb midlevel/elbow score (BB group). Strength, patient-reported outcomes (PROs), and safety were also evaluated. RESULTS: Parts 1 and 2 enrolled 37 and 58 participants, respectively. Among 55 participants evaluable in Part 2, the least-squares mean (90% confidence interval, analysis of covariance) treatment difference for TMV was 16.4% (9.8%-23.0%) in the BB group (P

ObjectiveTo determine whether locally acting ACE-083 is safe, well tolerated, and increases muscle volume, motor function, and quality of life (QoL) in adults with Charcot-Marie-Tooth disease (CMT) type 1.MethodsThis phase 2 study enrolled adults with CMT1 or CMTX (N=63). Part 1 was open-label and evaluated safety and tolerability of different dose levels of ACE-083 for use in Part 2. Part 2 was a randomized, placebo-controlled, 6-month study of 240 mg/muscle ACE-083 injected bilaterally in the tibialis anterior muscle, followed by a 6-month, open-label extension in which all patients received ACE-083. Pharmacodynamic endpoints included total muscle volume (TMV; primary endpoint), contractile muscle volume (CMV), and fat fraction. Additional secondary endpoints included 6-minute walk test, 10-meter walk/run, muscle strength, and QoL. Safety was assessed with treatment-emergent adverse events (TEAEs) and clinical laboratory tests.ResultsIn Part 1 (n=18), ACE-083 was generally safe and well tolerated at all dose levels, with no serious AEs, TEAEs ≥Grade 3, or death reported. In Part 2 (n=45 enrolled, n=44 treated), there was significantly greater change in TMV with ACE-083 compared with placebo (LS mean difference: 13.5%; p = 0.0096). There was significant difference between ACE-083 and placebo for CMV and change in ankle dorsiflexion strength. Fat fraction and all other functional outcomes were not significantly improved by ACE-083. Moderate-to-mild injection-site reactions were the most common TEAEs.ConclusionsDespite significantly increased TMV and CMV, patients with CMT receiving ACE-083 in tibialis anterior muscles did not demonstrate greater functional improvement compared with those receiving placebo.Classification of evidenceThis study provides Class II evidence that intramuscular ACE-083 is safe, well tolerated, and increases total muscle volume after 6 months of treatment in adults with CMT1 or CMTX.

Introduction/aimsThere is debate about whether and to what extent either respiratory or cardiac dysfunction occurs in patients with dysferlinopathy. This study aimed to establish definitively whether dysfunction in either system is part of the dysferlinopathy phenotype.MethodsAs part of the Jain Foundation's International Clinical Outcome Study (COS) for dysferlinopathy, objective measures of respiratory and cardiac function were collected twice, with a 3-y interval between tests, in 188 genetically confirmed patients aged 11-86 y (53% female). Measures included forced vital capacity (FVC), electrocardiogram (ECG), and echocardiogram (echo).ResultsMean FVC was 90% predicted at baseline, decreasing to 88% at year 3. FVC was less than 80% predicted in 44 patients (24%) at baseline and 48 patients (30%) by year 3, including ambulant participants. ECGs showed P-wave abnormalities indicative of delayed trans-atrial conduction in 58% of patients at baseline, representing a risk for developing atrial flutter or fibrillation. The prevalence of impaired left ventricular function or hypertrophy was comparable to that in the general population.DiscussionThese results demonstrate clinically significant respiratory impairment and abnormal atrial conduction in some patients with dysferlinopathy. Therefore, we recommend that annual or biannual follow-up should include FVC measurement, enquiry about arrhythmia symptoms and peripheral pulse palpation to assess cardiac rhythm. However, periodic specialist cardiac review is probably not warranted unless prompted by symptoms or abnormal pulse findings.

Background and objectivesWe investigated the prevalence of late-onset Pompe disease (LOPD) in patients presenting to 13 academic, tertiary neuromuscular practices in the United States and Canada.MethodsAll successive patients presenting with proximal muscle weakness or isolated hyperCKemia and/or neck muscle weakness to these 13 centers were invited to participate in the study. Whole blood was tested for acid alpha-glucosidase (GAA) assay through the fluorometric method, and all cases with enzyme levels of ≤10 pmoL/punch/h were reflexed to molecular testing for mutations in the GAA gene. Clinical and demographic information was abstracted from their clinical visit and, along with study data, entered into a purpose-built REDCap database, and analyzed at the University of California, Irvine.ResultsGAA enzyme assay results were available on 906 of the 921 participants who consented for the study. LOPD was confirmed in 9 participants (1% prevalence). Another 9 (1%) were determined to have pseudodeficiency of GAA, whereas 19 (1.9%) were found to be heterozygous for a pathogenic GAA mutation (carriers). Of the definite LOPD participants, 8 (89%) were Caucasian and were heterozygous for the common leaky (IVS1) splice site mutation in the GAA gene (c -32-13T>G), with a second mutation that was previously confirmed to be pathogenic.DiscussionThe prevalence of LOPD in undiagnosed patients meeting the criteria of proximal muscle weakness, high creatine kinase, and/or neck weakness in academic, tertiary neuromuscular practices in the United States and Canada is estimated to be 1%, with an equal prevalence rate of pseudodeficiency alleles.Trial registration informationClinical trial registration number: NCT02838368.

ObjectiveTo define the clinicopathologic features and diagnostic utility associated with anti-cytosolic 5'-nucleotidase 1A (NT5C1A) antibody seropositivity in idiopathic inflammatory myopathies (IIMs).MethodsAnti-NT5C1A antibody status was clinically tested between 2014 and 2019 in the Washington University neuromuscular clinical laboratory. Using clinicopathologic information available for 593 patients, we classified them as inclusion body myositis (IBM), dermatomyositis, antisynthetase syndrome, immune-mediated necrotizing myopathy (IMNM), nonspecific myositis, or noninflammatory muscle diseases.ResultsOf 593 patients, anti-NT5C1A antibody was found in 159/249 (64%) IBM, 11/53 (21%) dermatomyositis, 7/27 (26%) antisynthetase syndrome, 9/76 (12%) IMNM, 20/84 (24%) nonspecific myositis, and 6/104 (6%) noninflammatory muscle diseases patients. Among patients with IBM, anti-NT5C1A antibody seropositive patients had more cytochrome oxidase-negative fibers compared with anti-NT5C1A antibody seronegative patients. Among 14 IBM patients initially negative for anti-NT5C1A antibody, three patients (21%) converted to positive. Anti-NT5C1A antibody seropositivity did not correlate with malignancy, interstitial lung disease, response to treatments in dermatomyositis, antisynthetase syndrome, and IMNM, or survival in IIMs.InterpretationAnti-NT5C1A antibody is associated with IBM. However, the seropositivity can also be seen in non-IBM IIMs and it does not correlate with any prognostic factors or survival.

ObjectivesTo approximate the rate of familial myasthenia gravis and the coexistence of other autoimmune disorders in the patients and their families.DesignRetrospective cohort study.SettingClinics across North America.ParticipantsThe study included 1032 patients diagnosed with acetylcholine receptor antibody (AChR)-positive myasthenia gravis.MethodsPhenotype information of 1032 patients diagnosed with AChR-positive myasthenia gravis was obtained from clinics at 14 centres across North America between January 2010 and January 2011. A critical review of the epidemiological literature on the familial rate of myasthenia gravis was also performed.ResultsAmong 1032 patients, 58 (5.6%) reported a family history of myasthenia gravis. A history of autoimmune diseases was present in 26.6% of patients and in 28.4% of their family members.DiscussionThe familial rate of myasthenia gravis was higher than would be expected for a sporadic disease. Furthermore, a high proportion of patients had a personal or family history of autoimmune disease. Taken together, these findings suggest a genetic contribution to the pathogenesis of myasthenia gravis.

Abstract Background Water T2 (T2H2O) mapping is increasingly being used in muscular dystrophies to assess active muscle damage. It has been suggested as a surrogate outcome measure for clinical trials. Here, we investigated the prognostic utility of T2H2O to identify changes in muscle function over time in limb girdle muscular dystrophies. Methods Patients with genetically confirmed dysferlinopathy were assessed as part of the Jain Foundation Clinical Outcomes Study in dysferlinopathy. The cohort included 18 patients from two sites, both equipped with 3‐tesla magnetic resonance imaging (MRI) systems from the same vendor. T2H2O value was defined as higher or lower than the median in each muscle bilaterally. The degree of deterioration on four functional tests over 3 years was assessed in a linear model against covariates of high or low T2H2O at baseline, age, disease duration, and baseline function. Results A higher T2H2O at baseline significantly correlated with a greater decline on functional tests in 21 out of 35 muscles and was never associated with slower decline. Higher baseline T2H2O in adductor magnus, vastus intermedius, vastus lateralis, and vastus medialis were the most sensitive, being associated bilaterally with greater decline in multiple timed tests. Patients with a higher than median baseline T2H2O (>40.6 ms) in the right vastus medialis deteriorated 11 points more on the North Star Ambulatory Assessment for Dysferlinopathy and lost an additional 86 m on the 6‐min walk than those with a lower T2H2O (

TAR DNA binding protein 43 (TDP-43) is an RNA binding protein that accumulates as aggregates in the central nervous systems of some patients with neurodegenerative diseases. However, TDP-43 aggregation is also a sensitive and specific pathologic feature found in a family of degenerative muscle diseases termed inclusion body myopathy. TDP-43 aggregates from amyotrophic lateral sclerosis (ALS) and frontotemporal dementia brain lysates may serve as self-templating aggregate seeds in vitro and in vivo, supporting a prion-like spread from cell to cell. Whether a similar process occurs in patient muscle is not clear. We developed a mouse model of inducible, muscle-specific cytoplasmic localized TDP-43. These mice develop muscle weakness with robust accumulation of insoluble and phosphorylated sarcoplasmic TDP-43, leading to eosinophilic inclusions, altered proteostasis, and changes in TDP-43–related RNA processing that resolve with the removal of doxycycline. Skeletal muscle lysates from these mice also have seeding-competent TDP-43, as determined by a FRET-based biosensor, that persists for weeks upon resolution of TDP-43 aggregate pathology. Human muscle biopsies with TDP-43 pathology also contain TDP-43 aggregate seeds. Using lysates from muscle biopsies of patients with sporadic inclusion body myositis (IBM), immune-mediated necrotizing myopathy (IMNM), and ALS, we found that TDP-43 seeding capacity was specific to IBM. TDP-43 seeding capacity anticorrelated with TDP-43 aggregate and vacuole abundance. These data support that TDP-43 aggregate seeds are present in IBM skeletal muscle and represent a unique TDP-43 pathogenic species not previously appreciated in human muscle disease. Editor's summary: Aggregates of TAR DNA binding protein 43 (TDP-43) have been previously linked with neurodegenerative disease as well as inclusion body myopathy in skeletal muscle. Here, Lynch et al. demonstrate that residual aggregates termed "seeds" can persist in muscle after larger aggregates have been cleared and are no longer visible by traditional methods. Using a Förster resonance energy transfer (FRET) biosensor system, they show that both human and mouse TDP-43 seeds can be the initiators of new aggregates that contribute to disease pathology. These results highlight the importance of protein homeostasis and suggest that these seeds may be a potential therapeutic target for ameliorating disease. —Allison Williams [ABSTRACT FROM AUTHOR]

Background: Late-onset Pompe disease (LOPD), a rare autosomal recessive multisystemic disorder, substantially impacts patients' day-to-day activities, outcomes, and health-related quality of life (HRQoL). The PROPEL trial compared cipaglucosidase alfa plus miglustat (cipa+mig) with alglucosidase alfa plus placebo (alg+pbo) in adult patients with LOPD over 52 weeks and showed improved motor and respiratory function in patients switching treatment from standard-of-care enzyme replacement therapy (ERT) to cipa+mig at baseline. This study evaluated the impact of cipa+mig on patient-reported outcomes (PROs), including HRQoL in ERT-experienced patients, using data from PROPEL. Methods: PROs evaluated included the Subject's Global Impression of Change (SGIC), Patient-Reported Outcomes Measurement Information System (PROMIS) Physical Function Short Form 20a, PROMIS Fatigue Short Form 8a, Rasch-built Pompe-specific Activity (R-PAct), and European Quality of Life-5 Dimensions 5 Response Levels (EQ-5D-5L). The proportions of responders in the cipa+mig arm and the alg+pbo arm were compared via chi-squared or Fisher's exact test (patient-level responder analysis), and least squares (LS) mean differences were calculated for change from baseline at Week 52 of the PRO measures (group-level analysis). Results: At Week 52, patient-level SGIC responder and group-level SGIC analyses favored cipa+mig compared with alg+pbo across all SGIC domains (e.g. 90 vs. 59% responders in the cipa+mig vs. the alg+pbo group for SGIC ability to move around; P = 0.0005; and LS mean difference 0.385; P = 0.02). Similarly, PROMIS Physical Function and Fatigue domains numerically favored cipa+mig in both analyses (e.g. 50 vs. 40% responders in the cipa+mig vs. alg+pbo arm for PROMIS Physical Function; P = 0.37; and LS mean difference 3.1; P = 0.11). R-PAct for both treatment groups was similar in the patient-level responder analysis, but numerically favored alg+pbo in the group-level analysis (35% responders in both arms; P = 0.95; and LS mean difference −0.8; P = 0.48). Self-care, usual activities, and depression/anxiety domains of EQ-5D-5L numerically favored cipa+mig in both analyses (e.g. 20 vs. 12% responders in the cipa+mig vs. alg+pbo arm for EQ-5D-5L self-care; P = 0.54; and LS mean difference −0.108; P = 0.52). Conclusions: Overall, switching treatment from alglucosidase alfa to cipa+mig positively impacted PRO measurements during the double-blind period of PROPEL. Trial registration: NCT03729362; Registration date: November 1, 2018; https://clinicaltrials.gov/study/NCT03729362 Plain English summary: Late-onset Pompe disease (LOPD) is a rare, multisystemic inherited genetic disease that causes glycogen accumulation in muscles and other body organs, leading to muscle weakness and respiratory insufficiency. LOPD significantly impacts patients' day-to-day life. Enzyme replacement therapies (ERT) have greatly improved the lives of patients with LOPD. The first approved ERT for LOPD was alglucosidase alfa (alg). To evaluate the effects of a new treatment (cipaglucosidase alfa+miglustat [cipa+mig]) in adult patients with LOPD, two-thirds of patients were switched from alg to cipa+mig and the remaining patients continued receiving alg (alg+placebo [alg+pbo]). We used patient-reported outcome (PRO) questionnaires (asking patients how they feel) to assess changes in patient health. Groups were similar at baseline. Analyses showed that patients improved following cipa+mig treatment for all domains of the PROs Subject's Global Impression of Change (SGIC; overall physical well-being, effort of breathing, muscle strength, muscle function, ability to move around, activities of daily living, energy level, level of muscular pain) and the Patient-Reported Outcomes Measurement Information System (PROMIS; Physical Function, Fatigue) compared with when treated with alg+pbo. Rasch-built Pompe-specific Activity (R-PAct), a survey evaluating daily activities and social life of patients living with Pompe disease, showed that patients felt similar after cipa+mig and alg+pbo. European Quality of Life-5 Dimensions-5 Response Levels (EQ-5D-5L), a measure of health covering five dimensions, favored cipa+mig in the self-care, usual activities, pain/discomfort and depression/anxiety areas, and alg+pbo for mobility. Overall, changing treatment from alg to cipa+mig positively affects PROs and the patient's general well-being. [ABSTRACT FROM AUTHOR]

OBJECTIVE: To characterize the pattern and extent of muscle weakness and impact on physical functioning in adults with GNEM. METHODS: Strength and function were assessed in GNEM subjects (n = 47) using hand-held dynamometry, manual muscle testing, upper and lower extremity functional capacity tests, and the GNEM-Functional Activity Scale (GNEM-FAS). RESULTS: Profound upper and lower muscle weakness was measured using hand-held dynamometry in a characteristic pattern, previously described. Functional tests and clinician-reported outcomes demonstrated the consequence of muscle weakness on physical functioning. CONCLUSIONS: The characteristic pattern of upper and lower muscle weakness associated with GNEM and the resulting functional limitations can be reliably measured using these clinical outcome assessments of muscle strength and function.

ImportanceUnderstanding the natural history of familial amyotrophic lateral sclerosis (ALS) caused by SOD1 mutations (ALSSOD1) will provide key information for optimising clinical trials in this patient population.ObjectiveTo establish an updated natural history of ALSSOD1.Design, setting and participantsRetrospective cohort study from 15 medical centres in North America evaluated records from 175 patients with ALS with genetically confirmed SOD1 mutations, cared for after the year 2000.Main outcomes and measuresAge of onset, survival, ALS Functional Rating Scale (ALS-FRS) scores and respiratory function were analysed. Patients with the A4V (Ala-Val) SOD1 mutation (SOD1A4V), the largest mutation population in North America with an aggressive disease progression, were distinguished from other SOD1 mutation patients (SOD1non-A4V) for analysis.ResultsMean age of disease onset was 49.7±12.3 years (mean±SD) for all SOD1 patients, with no statistical significance between SOD1A4V and SOD1non-A4V (p=0.72, Kruskal-Wallis). Total SOD1 patient median survival was 2.7 years. Mean disease duration for all SOD1 was 4.6±6.0 and 1.4±0.7 years for SOD1A4V. SOD1A4V survival probability (median survival 1.2 years) was significantly decreased compared with SOD1non-A4V (median survival 6.8 years; p