Search

Background and Objectives: The French Pompe disease registry was created in 2004 for study of the natural course of the disease in patients. It rapidly became a major tool for assessing the long-term efficacy of enzyme replacement therapy (ERT) after the market release of alglucosidase-alfa., Methods: Approximately 10 years after publication of the baseline characteristics of the 126 initial patients of the French Late-Onset Pompe Disease registry, we provide here an update of the clinical and biological features of patients included in this registry., Results: We describe 210 patients followed at 31 hospital-based French neuromuscular or metabolic centers. The median age at inclusion was 48.67 ± 14.91 years. The first symptom was progressive lower limb muscle weakness, either isolated (50%) or associated with respiratory symptoms (18%), at a median age of 38 ± 14.9 years. At inclusion, 64% of the patients were able to walk independently and 14% needed a wheelchair. Positive associations were found between motor function measure, manual motor test, and 6-minute walk test (6MWT) results, and these parameters were inversely associated with the time taken to sit up from a lying position at inclusion. Seventy-two patients had been followed for at least 10 years in the registry. Thirty-three patients remained untreated a median of 12 years after symptom onset. The standard ERT dose was administered for 177 patients., Discussion: This update confirms previous findings for the adult population included in the French Pompe disease registry, but with a lower clinical severity at inclusion, suggesting that this rare disease is now diagnosed earlier; thanks to greater awareness among physicians. The 6MWT remains an important method for assessing motor performance and walking ability. The French Pompe disease registry provides an exhaustive, nationwide overview of Pompe disease and can be used to assess individual and global responses to future treatments., (© 2023 American Academy of Neurology.)

Background and Objectives: Spinal muscular atrophy (SMA) is mainly caused by homozygous SMN1 gene deletions on 5q13. Non-5q SMA patients' series are lacking, and the diagnostic yield of next-generation sequencing (NGS) is largely unknown. The aim of this study was to describe the clinical and genetic landscape of non-5q SMA and evaluate the performance of neuropathy gene panels in these disorders., Methods: Description of patients with non-5q SMA followed in the different neuromuscular reference centers in France as well as in London, United Kingdom. Patients without a genetic diagnosis had undergone at least a neuropathy or large neuromuscular gene panel., Results: Seventy-one patients from 65 different families were included, mostly sporadic cases (60.6%). At presentation, 21 patients (29.6%) showed exclusive proximal weakness (P-SMA), 35 (49.3%) showed associated distal weakness (PD-SMA), and 15 (21.1%) a scapuloperoneal phenotype (SP-SMA). Thirty-two patients (45.1%) had a genetic diagnosis: BICD2 (n = 9), DYNC1H1 (n = 7), TRPV4 (n = 4), VCP , HSBP1 , AR (n = 2), VRK1 , DNAJB2 , MORC2 , ASAH1 , HEXB , and unexpectedly, COL6A3 (n = 1). The genetic diagnostic yield was lowest in P-SMA (6/21, 28.6%) compared with PD-SMA (16/35, 45.7%) and SP-SMA (10/15, 66.7%). An earlier disease onset and a family history of the disease or consanguinity were independent predictors of a positive genetic diagnosis. Neuropathy gene panels were performed in 59 patients with a 32.2% diagnostic yield (19/59). In 13 additional patients, a genetic diagnosis was achieved through individual gene sequencing or an alternative neuromuscular NGS., Discussion: Non-5q SMA is genetically heterogeneous, and neuropathy gene panels achieve a molecular diagnosis in one-third of the patients. The diagnostic yield can be increased by sequencing of other neuromuscular and neurometabolic genes. Nevertheless, there is an unmet need to cluster these patients to aid in the identification of new genes., Competing Interests: The authors report no relevant disclosures. Go to Neurology.org/NG for full disclosures., (Copyright © 2023 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the American Academy of Neurology.)

Background and Purpose: Biallelic variants in SORD have been reported as one of the main recessive causes for hereditary peripheral neuropathies such as Charcot-Marie-Tooth disease type 2 (CMT2) and distal hereditary motor neuropathy (dHMN) resulting in lower limb (LL) weakness and muscular atrophy. In this study, phenotype and genotype landscapes of SORD-related peripheral neuropathies were described in a French and Swiss cohort. Serum sorbitol dosages were used to classify SORD variants., Methods: Patients followed at neuromuscular reference centres in France and Switzerland were ascertained. Sanger sequencing and next generation sequencing were performed to sequence SORD, and mass spectrometry was used to measure patients' serum sorbitol., Results: Thirty patients had SORD peripheral neuropathy associating LL weakness with muscular atrophy, foot deformities (87%), and sometimes proximal LL weakness (20%) or distal upper limb weakness (50%). Eighteen had dHMN, nine had CMT2, and three had intermediate CMT. Most of them had a mild or moderate disease severity. Sixteen carried a homozygous c.757delG (p.Ala253Glnfs*27) variant, and 11 carried compound heterozygous variants, among which four variants were not yet reported: c.403C > G, c.379G > A, c.68_100 + 1dup, and c.850dup. Two unrelated patients with different origins carried a homozygous c.458C > A variant, and one patient carried a new homozygous c.786 + 5G > A variant. Mean serum sorbitol levels were 17.01 mg/L ± 8.9 SD for patients carrying SORD variants., Conclusions: This SORD-inherited peripheral neuropathy cohort of 30 patients showed homogeneous clinical presentation and systematically elevated sorbitol levels (22-fold) compared to controls, with both diagnostic and potential therapeutic implications., (© 2023 The Authors. European Journal of Neurology published by John Wiley & Sons Ltd on behalf of European Academy of Neurology.)

MORC2 gene encodes a ubiquitously expressed nuclear protein involved in chromatin remodeling, DNA repair, and transcriptional regulation. Heterozygous mutations in MORC2 gene have been associated with a spectrum of disorders affecting the peripheral nervous system such as Charcot-Marie-Tooth (CMT2Z), spinal muscular atrophy-like with or without cerebellar involvement, and a developmental syndrome associated with impaired growth, craniofacial dysmorphism and axonal neuropathy (DIGFAN syndrome). Such variability in clinical manifestations associated with the increasing number of variants of unknown significance detected by next-generation sequencing constitutes a serious diagnostic challenge. Here we report the characterization of an in vitro model to evaluate the pathogenicity of variants of unknown significance based on MORC2 overexpression in a neuroblastoma cell line SH-EP or cortical neurons. Likewise, we show that MORC2 mutants affect survival and trigger apoptosis over time in SH-EP cell line. Furthermore, overexpression in primary cortical neurons increases apoptotic cell death and decreases neurite outgrowth. Altogether, these approaches establish the pathogenicity of two new variants p.Gly444Arg and p.His446Gln in three patients from two families. These new mutations in MORC2 gene are associated with autosomal dominant CMT and with adult late onset proximal motor neuropathy, further increasing the spectrum of clinical manifestations associated with MORC2 mutations., (© 2022 The Authors. Human Mutation published by Wiley Periodicals LLC.)

Background: Valosin-containing protein (VCP) disease, caused by mutations in the VCP gene, results in myopathy, Paget's disease of bone (PBD) and frontotemporal dementia (FTD). Natural history and genotype-phenotype correlation data are limited. This study characterises patients with mutations in VCP gene and investigates genotype-phenotype correlations., Methods: Descriptive retrospective international study collecting clinical and genetic data of patients with mutations in the VCP gene., Results: Two hundred and fifty-five patients (70.0% males) were included in the study. Mean age was 56.8±9.6 years and mean age of onset 45.6±9.3 years. Mean diagnostic delay was 7.7±6 years. Symmetric lower limb weakness was reported in 50% at onset progressing to generalised muscle weakness. Other common symptoms were ventilatory insufficiency 40.3%, PDB 28.2%, dysautonomia 21.4% and FTD 14.3%. Fifty-seven genetic variants were identified, 18 of these no previously reported. c.464G>A (p.Arg155His) was the most frequent variant, identified in the 28%. Full time wheelchair users accounted for 19.1% with a median time from disease onset to been wheelchair user of 8.5 years. Variant c.463C>T (p.Arg155Cys) showed an earlier onset (37.8±7.6 year) and a higher frequency of axial and upper limb weakness, scapular winging and cognitive impairment. Forced vital capacity (FVC) below 50% was as risk factor for being full-time wheelchair user, while FVC <70% and being a full-time wheelchair user were associated with death., Conclusion: This study expands the knowledge on the phenotypic presentation, natural history, genotype-phenotype correlations and risk factors for disease progression of VCP disease and is useful to improve the care provided to patient with this complex disease., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2022. No commercial re-use. See rights and permissions. Published by BMJ.)

The objective was to investigate whether resveratrol (RSV) can improve exercise capacity in patients with fatty acid oxidation (FAO) disorders. The study was a randomized, double-blind, cross-over trial. Nine patients with very long-chain acyl-CoA dehydrogenase (VLCAD) deficiency or carnitine palmitoyl transferase (CPT) II deficiency were randomized to receive either 8 weeks of 1000 mg day -1 RSV or placebo (P) followed by a 4-weeks wash-out period and subsequently 8 weeks of the opposite treatment. Primary outcome measures were heart rate and FAO as measured via stable isotope technique during constant workload exercise. Secondary outcome measures included fat and glucose metabolism; perceived exertion; as well as subjective measures of energy expenditure, fatigue, and daily function. Eight participants completed the trial. Heart rate did not differ at the end of exercise after treatment with RSV vs placebo (P = .063). Rate of oxidation of palmitate at end of exercise was not different with 1.5 ± 0.8 (RSV) vs 1.3 ± 0.6 (P) μmol kg -1  min -1 (P = .109). Secondary outcomes did not change except for increased plasma glycerol and decreased plasma glucose levels at the end of exercise after treatment with RSV vs placebo. A daily dose of 1000 mg resveratrol does not improve exercise capacity or FAO during exercise in patients with CPTII or VLCAD deficiencies., (© 2022 SSIEM.)

Background and Purpose: Data on interruption of enzyme replacement therapy (ERT) are scarce in late onset Pompe disease. Due to the COVID-19 crisis, eight neuromuscular reference centers in France were obligated to stop the treatment for 31 patients., Methods: We collected the motor and respiratory data from our French registry, before COVID-19 and at treatment restart., Results: In 2.2 months (mean), patients showed a significant deterioration of 37 m (mean) in the 6-min walk test and a loss of 210 ml (mean) of forced vital capacity, without ad integrum restoration after 3 months of ERT restart., Conclusions: This national study based on data from the French Pompe Registry shows that the interruption of ERT, even as short as a few months, worsens Pompe patients' motor and respiratory function., (© 2021 European Academy of Neurology.)

Background: Facioscapulohumeral muscular dystrophy (FSHD) is among the most prevalent muscular dystrophies and currently has no treatment. Clinical and genetic heterogeneity are the main challenges to a full comprehension of the physiopathological mechanism. Improving our knowledge of FSHD is crucial to the development of future therapeutic trials and standards of care. National FSHD registries have been set up to this end. The French National Registry of FSHD combines a clinical evaluation form (CEF) and a self-report questionnaire (SRQ), filled out by a physician with expertise in neuromuscular dystrophies and by the patient, respectively. Aside from favoring recruitment, our strategy was devised to improve data quality. Indeed, the pairwise comparison of data from 281 patients for 39 items allowed for evaluating data accuracy. Kappa or intra-class coefficient (ICC) values were calculated to determine the correlation between answers provided in both the CEF and SRQ., Results: Patients and physicians agreed on a majority of questions common to the SRQ and CEF (24 out of 39). Demographic, diagnosis- and care-related questions were generally answered consistently by the patient and the medical practitioner (kappa or ICC values of most items in these groups were greater than 0.8). Muscle function-related items, i.e. FSHD-specific signs, showed an overall medium to poor correlation between data provided in the two forms; the distribution of agreements in this section was markedly spread out and ranged from poor to good. In particular, there was very little agreement regarding the assessment of facial motricity and the presence of a winged scapula. However, patients and physicians agreed very well on the Vignos and Brooke scores. The report of symptoms not specific to FSHD showed general poor consistency., Conclusions: Patient and physician answers are largely concordant when addressing quantitative and objective items. Consequently, we updated collection forms by relying more on patient-reported data where appropriate. We hope the revised forms will reduce data collection time while ensuring the same quality standard. With the advent of artificial intelligence and automated decision-making, high-quality and reliable data are critical to develop top-performing algorithms to improve diagnosis, care, and evaluate the efficiency of upcoming treatments., (© 2022. The Author(s).)

Background: The recent lockdown due to the COVID-19 pandemic has been linked to a higher incidence of psychiatric manifestations and substance abuse. The recreative use of nitrous oxide is more and more widespread and neurological complications are frequent., Methods: We report clinical characteristics and biological findings of five consecutive patients presenting to our tertiary care center between April 2020 and February 2021 with various neurological symptoms occurring after recent nitrous oxide abuse., Results: Our patients presented with subacute combined degeneration of the spinal cord (4/5 patients) or with acute inflammatory demyelinating polyneuropathy (1/5 patients). No patient had reduced vitamin B-12 titer, but all had elevated blood levels of homocysteine and methylmalonic acid. This reflects the functional deficit in vitamin B-12 that can be linked to nitrous oxide consumption. After vitamin B-12 supplementation, clinical signs regressed at least partially in all 5 patients., Conclusion: We report an elevated incidence of neurological complications of nitrous oxide abuse occurring during the recent COVID-19 lockdown. Nitrous oxide abuse should be tracked down in patients presenting with compatible neurological symptoms and elevated homocysteinemia. Vitamin B-12 should be supplemented as soon as the diagnosis is made., (© 2021. Springer-Verlag GmbH Germany, part of Springer Nature.)

The MYOMEX study was a multicentre, randomised, double-blind, placebo-controlled, cross-over study aimed to compare the effects of mexiletine vs. placebo in patients with myotonia congenita (MC) and paramyotonia congenita (PC). The primary endpoint was the self-reported score of stiffness severity on a 100 mm visual analogic scale (VAS). Mexiletine treatment started at 200 mg/day and was up-titrated by 200 mg increment each three days to reach a maximum dose of 600 mg/day for total treatment duration of 18 days for each cross-over period. The modified intent-to-treat population included 25 patients (13 with MC and 12 with PC; mean age, 43.0 years; male, 68.0%). The median VAS score for mexiletine was 71.0 at baseline and decreased to 16.0 at the end of the treatment while the score did not change for placebo (81.0 at baseline vs. 78.0 at end of treatment). A mixed effects linear model analysis on ranked absolute changes showed a significant effect of treatment (p < 0.001). The overall score of the Individualized Neuromuscular Quality of Life questionnaire (INQoL) was significantly improved (p < 0.001). No clinically significant adverse events were reported. In conclusion, mexiletine improved stiffness and quality of life in patients with nondystrophic myotonia and was well tolerated., (Copyright © 2021 The Authors. Published by Elsevier B.V. All rights reserved.)

Background: Due to their health condition, patients with neuromuscular diseases (NMD) are at greater risk of developing serious complications with COVID-19. The objective of this study was to analyze the prevalence of COVID-19 among NMD patients and the risk factors for its impact and severity during the first wave of the pandemic. Clinical data were collected from NMD-COVID-19 patients, between March 25, 2020 and May 11, 2020 in an anonymous survey carried out by expert physicians from the French Health Care Network Filnemus., Results: Physicians reported 84 patients, including: 34 with myasthenia gravis, 27 with myopathy and 23 with neuropathy. COVID-19 had no effect on NMD for 48 (58%) patients and 48 (58%) patients developed low COVID-19 severity. COVID-19 caused the death of 9 (11%) NMD patients. Diabetic patients were at greater risk of dying. Patients with diabetes, hypertension or severe forms of NMD had a higher risk of developing a moderate or severe form of COVID-19. In our cohort, corticosteroids and other immunosuppressants were not significantly associated with higher COVID-19 severity for acquired NMD., Conclusion: During this period, a small percentage of French NMD patients was affected by COVID-19 compared to the general French population and COVID-19 had a limited short-term effect on them. Diabetes, hypertension and a severe degree of NMD were identified as risk factors of unfavorable outcome following COVID-19. Conversely, in our cohort of patients with acquired NMD, corticosteroids or other immunosuppressants did not appear to be risk factors for more severe COVID-19., (© 2021. The Author(s).)

Objective: Cerebellar ataxia with neuropathy and vestibular areflexia syndrome (CANVAS) is a recessively inherited multisystem ataxia compromising cerebellar, vestibular, and sensory nerves, which has been associated to a pathogenic AAGGG(n) biallelic expansion repeat in the RFC1 gene. Our objective was to assess its prevalence in a French cohort of patients with idiopathic sporadic late-onset ataxia (ILOA), idiopathic early-onset ataxia (IEOA), or Multiple System Atrophy of Cerebellar type (MSA-C)., Methods: 163 patients were recruited in 3 French tertiary centers: 100 ILOA, 21 IEOA, and 42 patients with possible or probable MSA-C., Results: A pathogenic biallelic RFC1 AAGGG(n) repeat expansion was found in 15 patients: 15/100 in the ILOA group, but none in the IEOA and MSA-C subgroups. 14/15 patients had a CANVAS phenotype. Only 1/15 had isolated cerebellar ataxia, but also shorter biallelic expansions. Two RFC1 AAGGG(n) alleles were found in 78% of patients with a CANVAS phenotype. In one post-mortem case, the pathophysiological involvement of cerebellum and medullar posterior columns was found., Conclusion: Our study confirms the genetic heterogeneity of the CANVAS and that RFC1 repeat expansions should be searched for preferentially in case of unexplained ILOA associated with a sensory neuronopathy, but not particularly in patients classified as MSA-C., (© 2021. Springer-Verlag GmbH, DE part of Springer Nature.)

Background: To describe the clinical, pathological, and molecular characteristics of late-onset (LO) dysferlinopathy patients., Methods: Retrospective series of patients with LO dysferlinopathy, defined by an age at onset of symptoms ≥30 years, from neuromuscular centers in France and the International Clinical Outcome Study for dysferlinopathy (COS). Patients with early-onset (EO) dysferlinopathy (<30 years) were randomly selected from the COS study as a control group, and the North Star Assessment for Dysferlinopathy (NSAD) and Activity Limitation (ACTIVLIM) scores were used to assess functionality. Muscle biopsies obtained from 11 LO and 11 EO patients were revisited., Results: Forty-eight patients with LO dysferlinopathy were included (28 females). Median age at onset of symptoms was 37 (range 30-57) years and most patients showed a limb-girdle (n = 26) or distal (n = 10) phenotype. However, compared with EO dysferlinopathy patients (n = 48), LO patients more frequently showed atypical phenotypes (7 vs. 1; p = 0.014), including camptocormia, lower creatine kinase levels (2855 vs. 4394 U/L; p = 0.01), and higher NSAD (p = 0.008) and ACTIVLIM scores (p = 0.016). Loss of ambulation in LO patients tended to occur later (23 ± 4.4 years after disease onset vs. 16.3 ± 6.8 years; p = 0.064). Muscle biopsy of LO patients more frequently showed an atypical pattern (unspecific myopathic changes) as well as significantly less necrosis regeneration and inflammation. Although LO patients more frequently showed missense variants (39.8% vs. 23.9%; p = 0.021), no differences in dysferlin protein expression were found on Western blot., Conclusions: Late-onset dysferlinopathy patients show a higher frequency of atypical presentations, are less severely affected, and show milder dystrophic changes in muscle biopsy., (© 2021 European Academy of Neurology.)

Objective: To describe the clinical characteristics and outcomes of coronavirus disease 2019 (COVID-19) among patients with myasthenia gravis (MG) and identify factors associated with COVID-19 severity in patients with MG., Methods: The CO-MY-COVID registry was a multicenter, retrospective, observational cohort study conducted in neuromuscular referral centers and general hospitals of the FILNEMUS (Filière Neuromusculaire) network (between March 1, 2020, and June 8, 2020), including patients with MG with a confirmed or highly suspected diagnosis of COVID-19. COVID-19 was diagnosed based on a PCR test from a nasopharyngeal swab or severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) serology, thoracic CT scan, or typical symptoms. The main outcome was COVID-19 severity based on location of treatment/management (home, hospitalized in a medical unit, or in an intensive care unit). We collected information on demographic variables, general history, and risk factors for severe COVID-19. Multivariate ordinal regression models were used to identify factors associated with severe COVID-19 outcomes., Results: Among 3,558 patients with MG registered in the French database for rare disorders, 34 (0.96%) had COVID-19. The mean age at COVID-19 onset was 55.0 ± 19.9 years (mean MG duration: 8.5 ± 8.5 years). By the end of the study period, 28 patients recovered from COVID-19, 1 remained affected, and 5 died. Only high Myasthenia Gravis Foundation of America (MGFA) class (≥IV) before COVID-19 was associated with severe COVID-19 ( p = 0.004); factors that were not associated included sex, MG duration, and medium MGFA classes (≤IIIb). The type of MG treatment had no independent effect on COVID-19 severity., Conclusions: This registry-based cohort study shows that COVID-19 had a limited effect on most patients, and immunosuppressive medications and corticosteroids used for MG management are not risk factors for poorer outcomes. However, the risk of severe COVID-19 is elevated in patients with high MGFA classes (odds ratio, 102.6 [4.4-2,371.9]). These results are important for establishing evidence-based guidelines for the management of patients with MG during the COVID-19 pandemic., (© 2021 American Academy of Neurology.)

Importance: The tapering of prednisone therapy in generalized myasthenia gravis (MG) presents a therapeutic dilemma; however, the recommended regimen has not yet been validated., Objective: To compare the efficacy of the standard slow-tapering regimen of prednisone therapy with a rapid-tapering regimen., Design: From June 1, 2009, to July 31, 2013, a multicenter, parallel, single-blind randomized trial was conducted to compare 2 regimens of prednisone tapering. Data analysis was conducted from February 18, 2019, to January 23, 2020. A total of 2291 adults with a confirmed diagnosis of moderate to severe generalized MG at 7 specialized centers in France were assessed for eligibility., Interventions: The slow-tapering arm included a gradual increase of the prednisone dose to 1.5 mg/kg every other day and a slow decrease once minimal manifestation status of MG was attained. The rapid-tapering arm consisted of immediate high-dose daily administration of prednisone, 0.75 mg/kg, followed by an earlier and rapid decrease once improved MG status was attained. Azathioprine, up to a maximum dose of 3 mg/kg/d, was prescribed for all participants., Main Outcomes and Measures: The primary outcome was attainment of minimal manifestation status of MG without prednisone at 12 months and without clinical relapse at 15 months. Intention-to-treat analysis was conducted., Results: Of the 2291 patients assessed, 2086 did not fulfill the inclusion criteria, 87 declined to participate, and 1 patient registered after trial closure. A total of 117 patients (58 in the slow-tapering arm and 59 in the rapid-tapering arm) were selected for inclusion by MG specialists and were randomized. The population included 62 men (53%); median age was 65 years (interquartile range, 35-69 years). The proportion of patients having met the primary outcome was higher in the rapid- vs slow-tapering arm (23 [39%] vs 5 [9%]), with a risk ratio of 3.61 (95% CI, 1.64-7.97; P < .001) after adjusting for center and thymectomy. The rapid-tapering regimen allowed sparing of a mean of 1898 mg (95% CI, -3121 to -461 mg) of prednisone over 1 year (ie, 5.3 mg/d per patient, P = .03). The number of serious adverse events did not differ significantly between the slow- vs rapid-tapering group (13 [22%] vs 21 [36%], P = .15)., Conclusions and Relevance: In patients with moderate to severe generalized MG who require high-dose prednisone with azathioprine therapy, rapid tapering of prednisone appears to be feasible, well tolerated, and associated with a good outcome., Trial Registration: ClinicalTrials.gov Identifier: NCT00987116.

Becker muscular dystrophy (BMD) is a rare hereditary neuromuscular disease, caused by a genetic defect in the Duchenne Muscular Dystrophy (DMD) gene. We studied the natural history of respiratory function and its affecting factors in 23 adult BMD patients. These important data are needed for (future) clinical trials in BMD but are largely lacking. Patients had a median age of 51 years (28-78y) and median follow-up duration of 14 years (2-25y). We analysed 190 pulmonary function measurements with a median interval of one year (1-17y) and measured a 1.00% decline of Forced Vital Capacity percent predicted (FVC%pred) per year (p = 0.004). Loss of ambulation significantly increased the annual rate of FVC decline and was dependent of patient's body mass index (BMI; p = 0.015), with increases in BMI correlating with an even more rapid deterioration of FVC. A decline in Medical Research Council (MRC) sum score was significantly correlated with a decline in FVC (p = 0.003). We conclude that adult BMD patients experience a significant but mild respiratory decline. However, this decline is significantly more rapid and clinically relevant after loss of ambulation, which warrants a more vigilant follow-up of respiratory function in this subgroup., Competing Interests: Declaration of Competing Interest KGC is Chairholder of the Emil von Behring Chair for Neuromuscular and Neurodegenerative Disorders by CSL Behring. KGC and several authors of this publication are member of the European Reference Network for Rare Neuromuscular Diseases (ERN EURO-NMD) and of the European Reference Network for Rare Neurological Diseases (ERN-RND). The authors have no competing interests., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Despite a wide clinical spectrum, the adult form of Pompe disease is the most common one, and represents more than 90% of diagnosed patients in France. Since the marketing of enzyme replacement therapy (alglucosidase alfa, Myozyme), all reports to date in adults demonstrated an improvement of the walking distance, and a trend toward stabilization of respiratory function, but the majority of these studies were less than 5 years of duration. We report here the findings from 158 treated patients included in the French Pompe Registry, who underwent regular clinical assessments based on commonly used standardized tests (6-minute walking test, MFM scale, sitting vital capacity, MIP and MEP). For longitudinal analyses, the linear mixed effects models were used to assess trends in primary endpoints over time under ERT. A two-phase model better described the changes in distance traveled in the 6-minute walk test and MFM. 6MWT showed an initial significant increase (1.4% ± 0.5/year) followed by a progressive decline (-2.3%/year), with a cut-off point at 2.2 years. A similar pattern was observed in total MFM score (6.6% ± 2.3/year followed by a - 1.1%/year decline after 0.5 years). A single-phase decline with a slope of -0.9 ± 0.1%/year (P < .001) was observed for FVC, and MEP remained stable over the all duration of follow-up. This study provides further evidence that ERT improves walking abilities and likely stabilizes respiratory function in adult patients with Pompe disease, with a ceiling effect for the 6MWT in the first 3 years of treatment., (© 2020 SSIEM.)

Background and Purpose: Fifteen percent of patients with myasthenia gravis (MG) are refractory to conventional treatment. Case reports and a few studies show probable benefit of rituximab in these cases. Our objective was to assess the efficacy and the safety of rituximab in patients with MG, in a multicentric real-life study., Method: Inclusion criteria were: age > 18 years; MG with anti-acetylcholine receptor (AChR) antibodies, anti-muscle-specific kinase (MuSk) antibodies or significant decrement after repetitive nerve stimulation; Myasthenia Gravis Foundation of America (MGFA) class >II; refractory or steroid-dependent MG; and treatment with rituximab. Efficacy was assessed at 6 months using the MGFA-post-intervention status (PIS) score, the myasthenic muscle score (MMS) and the number of patients receiving steroids <10 mg/day. Data on adverse events were collected., Results: Twenty-nine patients were included: 20 with anti-AChR MG, five with anti-MuSK MG and four with seronegative MG. MGFA-PIS score was improved or better (improved, minimal manifestations or remission) in 86.2% of patients after 6 months of treatment (P < 0.0001). The mean MMS increased from 68.8 to 83.1 (P < 0.0001). A decrease in steroid dosage (<10 mg/day) was effective in 57.9% of treated patients. In all, 42.8% of patients experienced adverse events: infections (21.4% of patients); infusion reaction (7%); bradycardia (3.7%); and cytopenia (7%)., Conclusion: The present study demonstrates the efficacy and safety of rituximab in patients with MG. Additional studies remain necessary to determine the role of rituximab in the pharmacopeia of MG treatment and to establish precise recommendations for the infusion protocol., (© 2020 European Academy of Neurology.)

Glycogen storage disorder type III (GSDIII), or debranching enzyme (GDE) deficiency, is a rare metabolic disorder characterized by variable liver, cardiac, and skeletal muscle involvement. GSDIII manifests with liver symptoms in infancy and muscle involvement during early adulthood. Muscle biopsy is mainly performed in patients diagnosed in adulthood, as routine diagnosis relies on blood or liver GDE analysis, followed by AGL gene sequencing. The GSDIII mouse model recapitulate the clinical phenotype in humans, and a nearly full rescue of muscle function was observed in mice treated with the dual AAV vector expressing the GDE transgene.In order to characterize GSDIII muscle morphological spectrum and identify novel disease markers and pathways, we performed a large international multicentric morphological study on 30 muscle biopsies from GSDIII patients. Autophagy flux studies were performed in human muscle biopsies and muscles from GSDIII mice. The human muscle biopsies revealed a typical and constant vacuolar myopathy, characterized by multiple and variably sized vacuoles filled with PAS-positive material. Using electron microscopy, we confirmed the presence of large non-membrane bound sarcoplasmic deposits of normally structured glycogen as well as smaller rounded sac structures lined by a continuous double membrane containing only glycogen, corresponding to autophagosomes. A consistent SQSTM1/p62 decrease and beclin-1 increase in human muscle biopsies suggested an enhanced autophagy. Consistent with this, an increase in the lipidated form of LC3, LC3II was found in patients compared to controls. A decrease in SQSTM1/p62 was also found in the GSDIII mouse model.In conclusion, we characterized the morphological phenotype in GSDIII muscle and demonstrated dysfunctional autophagy in GSDIII human samples.These findings suggest that autophagic modulation combined with gene therapy might be considered as a novel treatment for GSDIII.

Background: An accurate estimation of the risk of life-threatening (LT) ventricular tachyarrhythmia (VTA) in patients with LMNA mutations is crucial to select candidates for implantable cardioverter-defibrillator implantation., Methods: We included 839 adult patients with LMNA mutations, including 660 from a French nationwide registry in the development sample, and 179 from other countries, referred to 5 tertiary centers for cardiomyopathies, in the validation sample. LTVTA was defined as (1) sudden cardiac death or (2) implantable cardioverter defibrillator-treated or hemodynamically unstable VTA. The prognostic model was derived using the Fine-Gray regression model. The net reclassification was compared with current clinical practice guidelines. The results are presented as means (SD) or medians [interquartile range]., Results: We included 444 patients, 40.6 (14.1) years of age, in the derivation sample and 145 patients, 38.2 (15.0) years, in the validation sample, of whom 86 (19.3%) and 34 (23.4%) experienced LTVTA over 3.6 [1.0-7.2] and 5.1 [2.0-9.3] years of follow-up, respectively. Predictors of LTVTA in the derivation sample were: male sex, nonmissense LMNA mutation, first degree and higher atrioventricular block, nonsustained ventricular tachycardia, and left ventricular ejection fraction (https://lmna-risk-vta.fr). In the derivation sample, C-index (95% CI) of the model was 0.776 (0.711-0.842), and the calibration slope 0.827. In the external validation sample, the C-index was 0.800 (0.642-0.959), and the calibration slope was 1.082 (95% CI, 0.643-1.522). A 5-year estimated risk threshold ≥7% predicted 96.2% of LTVTA and net reclassified 28.8% of patients with LTVTA in comparison with the guidelines-based approach., Conclusions: In comparison with the current standard of care, this risk prediction model for LTVTA in laminopathies significantly facilitated the choice of candidates for implantable cardioverter defibrillators., Clinical Trial Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT03058185.

Programmed death receptor 1 (PD1) checkpoint inhibitors are known for immune mediated toxicities such as colitis, endocrinopathies and pneumonitis. However, other rare adverse effects are reported in the literature. Nivolumab is an anti-PD1 immunotherapy used in the second line of non-small cell lung cancer (NSCLC). We report two cases of rare toxicities occurring under nivolumab in patients without a history of dysimmunity. A 79-year-old patient with a large-cell carcinoma showed a muscle weakness after the second course, revealing myositis with a CPK grade IV elevation as well as symptoms of myasthenia. The diagnosis of myositis was confirmed by a muscle biopsy. An 82-year-old patient followed for bronchial adenocarcinoma with EGFR mutation, presented with nivolumab shoulder and hip pain with extreme fatigue. After further investigations, the diagnosis of systemic erythematosus lupus was retained. Investigations led to the diagnosis of systemic lupus erythematosus. For both patients treatment was interrupted and systemic corticosteroid therapy was initiated permitting resolution of symptoms. The occurrence of symptoms of dysimmunity should attract the attention of the clinician, leading to discontinuation of anti-PD1 therapy and corticosteroid therapy. Retreatment after symptoms resolution must be collegially discussed if no alternative therapeutic is available., (Copyright © 2017 Elsevier Masson SAS. All rights reserved.)

Mutations in GFPT1 (glutamine-fructose-6-phosphate transaminase 1), a gene encoding an enzyme involved in glycosylation of ubiquitous proteins, cause a limb-girdle congenital myasthenic syndrome (LG-CMS) with tubular aggregates (TAs) characterized predominantly by affection of the proximal skeletal muscles and presence of highly organized and remodeled sarcoplasmic tubules in patients' muscle biopsies. We report here the first long-term clinical follow-up of 11 French individuals suffering from LG-CMS with TAs due to GFPT1 mutations, of which nine are new. Our retrospective clinical evaluation stresses an evolution toward a myopathic weakness that occurs concomitantly to ineffectiveness of usual CMS treatments. Analysis of neuromuscular biopsies from three unrelated individuals demonstrates that the maintenance of neuromuscular junctions (NMJs) is dramatically impaired with loss of post-synaptic junctional folds and evidence of denervation-reinnervation processes affecting the three main NMJ components. Moreover, molecular analyses of the human muscle biopsies confirm glycosylation defects of proteins with reduced O-glycosylation and show reduced sialylation of transmembrane proteins in extra-junctional area. Altogether, these results pave the way for understanding the etiology of this rare neuromuscular disorder that may be considered as a "tubular aggregates myopathy with synaptopathy".

Glycogen storage disease type III is an inherited metabolic disorder characterized by liver and muscle impairment. This study aimed to identify promising muscle function measures for future studies on natural disease progression and therapeutic trials. The age-effect on the manual muscle testing (MMT), the hand-held dynamometry (HHD), the motor function measure (MFM) and the Purdue pegboard test was evaluated by regression analysis in a cross-sectional retrospective single site study. In patients aged between 13 and 56 years old, the Purdue pegboard test and dynamometry of key pinch and knee extension strength were age-sensitive with annual losses of 1.49, 1.10 and 0.70% of the predicted values (%pred), respectively. The MFM score and handgrip strength were also age-sensitive but only in patients older than 29 and 37 years old with annual losses of 1.42 and 1.84%pred, respectively. Muscle strength assessed by MMT and elbow extension measured by HHD demonstrated an annual loss of less than 0.50%pred and are thus unlikely to be promising outcome measures for future clinical trials. In conclusion, our results identified age-sensitive outcomes from retrospective data and may serve for future longitudinal studies in which an estimation of the minimal number of subjects is provided., (Copyright © 2016 Elsevier B.V. All rights reserved.)

The m.8344A>G mutation in the MTTK gene, which encodes the mitochondrial transfer RNA for lysine, is traditionally associated with myoclonic epilepsy and ragged-red fibres (MERRF), a multisystemic mitochondrial disease that is characterised by myoclonus, seizures, cerebellar ataxia, and mitochondrial myopathy with ragged-red fibres. We studied the clinical and paraclinical phenotype of 34 patients with the m.8344A>G mutation, mainly derived from the nationwide mitoREGISTER, the multicentric registry of the German network for mitochondrial disorders (mitoNET). Mean age at symptom onset was 24.5 years ±10.9 (6-48 years) with adult onset in 75 % of the patients. In our cohort, the canonical features seizures, myoclonus, cerebellar ataxia and ragged-red fibres that are traditionally associated with MERRF, occurred in only 61, 59, 70, and 63 % of the patients, respectively. In contrast, other features such as hearing impairment were even more frequently present (72 %). Other common features in our cohort were migraine (52 %), psychiatric disorders (54 %), respiratory dysfunction (45 %), gastrointestinal symptoms (38 %), dysarthria (36 %), and dysphagia (35 %). Brain MRI revealed cerebral and/or cerebellar atrophy in 43 % of our patients. There was no correlation between the heteroplasmy level in blood and age at onset or clinical phenotype. Our findings further broaden the clinical spectrum of the m.8344A>G mutation, document the large clinical variability between carriers of the same mutation, even within families and indicate an overlap of the phenotype with other mitochondrial DNA-associated syndromes.

Tubular aggregate myopathy is a genetically heterogeneous disease characterized by tubular aggregates as the hallmark on muscle biopsy. Mutations in STIM1 have recently been identified as one genetic cause in a number of tubular aggregate myopathy cases. To characterize the pattern of muscle involvement in this disease, upper and lower girdles and lower limbs were imaged in five patients with mutations in STIM1, and the scans were compared with two patients with tubular aggregate myopathy not caused by mutations in STIM1. A common pattern of involvement was found in STIM1-mutated patients, although with variable extent and severity of lesions. In the upper girdle, the subscapularis muscle was invariably affected. In the lower limbs, all the patients showed a consistent involvement of the flexor hallucis longus, which is very rarely affected in other muscle diseases, and a diffuse involvement of thigh and posterior leg with sparing of gracilis, tibialis anterior and, to a lesser extent, short head of biceps femoris. Mutations in STIM1 are associated with a homogeneous involvement on imaging despite variable clinical features. Muscle imaging can be useful in identifying STIM1-mutated patients especially among other forms of tubular aggregate myopathy., (Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.)

Background: Glycogen storage disease type III (GSDIII) is a rare autosomal recessive disorder due to glycogen debranching enzyme (GDE) deficiency. It results in a multisystemic disease with predominant hepatic and myopathic symptoms. While frequent social maladjustment has been observed in our clinical practice, cognitive and psychological disturbances have never been assessed. The aim of this pilot study was to examine and characterize the cognitive profile of patients with GSDIII., Methods: Seven patients (six women and one man, mean age: 38.7 ± 11.6 years) with GSDIII underwent a neuropsychological set of tests assessing global cognitive efficiency, executive functions, social cognition, apathy, and episodic memory., Results: All patients presented previous psychopathological history. We observed attention fluctuations for each patient, and impaired global cognitive efficiency with deficiencies in executive functions in 5/7 patients. Emotional skills (social cognition) were impaired in five patients. Memory was mostly preserved., Conclusion: The impairment in social cognition (recognition of emotions and ability to attribute mental states to others) and executive functions observed could be a consequence of orbito-frontal dysfunction due to the abnormal glycogen metabolism characteristic of the underlying disease. These results are consistent with the hypothesis of a central nervous system involvement in patients with GSDIII, but need to be confirmed in future research. This could explain the social and economic difficulties, and the lack of compliance to the medical follow-up presented by these patients. It suggests that these disturbances need to be taken into account when planning the medical management of patients with GSDIII.

Background: Tubular aggregate myopathies (TAMs) are muscle disorders characterised by abnormal accumulations of densely packed single-walled or double-walled membrane tubules in muscle fibres. Recently, STIM1, encoding a major calcium sensor of the endoplasmic reticulum, was identified as a TAM gene., Methods: The present study aims to define the clinical, histological and ultrastructural phenotype of tubular aggregate myopathy and to assess the STIM1 mutation spectrum., Results: We describe six new TAM families harbouring one known and four novel STIM1 mutations. All identified mutations are heterozygous missense mutations affecting highly conserved amino acids in the calcium-binding EF-hand domains, demonstrating the presence of a mutation hot spot for TAM. We show that the mutations induce constitutive STIM1 clustering, strongly suggesting that calcium sensing and consequently calcium homoeostasis is impaired. Histological and ultrastructural analyses define a common picture with tubular aggregates labelled with Gomori trichrome and Nicotinamide adenine dinucleotide (NADH) tetrazolium reductase, substantiating their endoplasmic reticulum origin. The aggregates were observed in both fibre types and were often accompanied by nuclear internalisation and fibre size variability. The phenotypical spectrum ranged from childhood onset progressive muscle weakness and elevated creatine kinase levels to adult-onset myalgia without muscle weakness and normal CK levels., Conclusions: The present study expands the phenotypical spectrum of STIM1-related tubular aggregate myopathy. STIM1 should therefore be considered for patients with tubular aggregate myopathies involving either muscle weakness or myalgia as the first and predominant clinical sign., (Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.)

Myotonic dystrophy (DM) is the most common muscular dystrophy in adults. Two known genetic subtypes include DM1 (myotonic dystrophy type 1) and DM2 (myotonic dystrophy type 2). Genetic testing is considered as the only reliable diagnostic criterion in myotonic dystrophies. Relatively little is known about DM1 and DM2 myopathology. Thus, the aim of our study was to characterise light and electron microscopic features of DM1 and DM2 in patients with genetically proven types of the disease. We studied 3 DM1 cases and 15 DM2 cases from which muscle biopsies were taken for diagnostic purposes during the period from 1973 to 2006, before genetic testing became available at our hospital. The DM1 group included 3 males (age at biopsy 15-19). The DM2 group included 15 patients (5 men and 10 women, age at biopsy 26-60). The preferential type 1 fibre atrophy was seen in all three DM1 cases in light microscopy, and substantial central nucleation was present in two biopsies. Electron microscopy revealed central nuclei in all three examined muscle biopsies. No other structural or degenerative changes were detected, probably due to the young age of our patients. Central nucleation, prevalence of type 2 muscle fibres, and the presence of pyknotic nuclear clumps were observed in DM2 patients in light microscopy. Among the ultrastructural abnormalities observed in our DM2 group, the presence of internal nuclei, severely atrophied muscle fibres, and lipofuscin accumulation were consistent findings. In addition, a variety of ultrastructural abnormalities were identified by us in DM2. It appears that no single ultrastructural abnormality is characteristic for the DM2 muscle pathology. It seems, however, that certain constellations of morphological changes might be indicative of certain types of myotonic dystrophy.

Muscle biopsy is required to provide a definitive diagnosis in many neuromuscular disorders. Biopsy findings may indicate whether the pathological process is of neurogenic or myopathic origin. The muscle biopsy may give important information on the course of the disease (acute or chronic) and on the disease stage and progression. The interpretation of muscle biopsy, including histochemical and ultrastructural analysis, is a key factor in the diagnosis of muscular dystrophies, glycogenoses, inflammatory myopathies and congenital myopathies. An assessment of muscle biopsy on electron microscopy enables a definite diagnosis of oculopharyngeal muscular dystrophy, mitochondrial myopathy or inclusion body myositis. This paper presents an overview of general indications for muscle biopsy, biopsy procedures, as well as transportation and preparation of muscle tissue for final microscopic analysis. The interpretation of specific microscopic findings and a brief discussion on the clinical usefulness of muscle biopsy in the era of molecular diagnosis are also presented.

Debranching enzyme deficiency (Glycogen storage disease (GSD) type III) causes progressive muscle wasting myopathy. A comprehensive nuclear magnetic resonance study involving spectroscopy (NMRS) and imaging (NMRI) evaluated status and function of calf muscles in 18 GSDIII patients. At rest, (31)P NMRS showed elevated pH and accumulation of anomalous phosphomonoesters, (13)C NMRS quantified excess glycogen accumulation and NMRI demonstrated progressive fat replacement that paralleled muscle weakness. Multi-parametric functional NMR, performed at recovery from a single bout of aerobic exercise, simultaneously assessed oxidative phosphorylation from (31)P NMRS, muscle perfusion and BOLD, a marker of blood oxygenation, from arterial spin labeled NMRI, and oxygen uptake from deoxymyoglobin proton NMRS. While blocked glycogenolysis caused inadequate substrate supply to the mitochondria, combined measurements suggested that altered perfusion was also responsible for impaired post-exercise phosphocreatine recovery and could contribute to exercise intolerance in GSDIII. These non-invasive investigations provide new indices to quantify the progression of GSDIII., (2010 Elsevier B.V. All rights reserved.)

Background and Purpose: Oculopharyngeal muscular dystrophy (OPMD) is mostly an autosomal dominant myopathic disorder, characterized by progressive bilateral ptosis, dysphagia and proximal muscle weakness, appearing usually in the fifth to sixth decade of life. The underlying cause of OPMD is an expanded GCG repeat in the first exon of the gene encoding poly (A)-binding protein nuclear 1 (PABPN1) localized on chromosome 14.q11.2-q13. The number of GCG expansion ranges from 8 to 13 repeats. PABPN1 is a nuclear multifunctional protein which is involved in transcription regulation and post-transcriptional processes., Material and Methods: We report on clinical characteristics in 9 Polish patients with genetically confirmed OPMD., Results: The expanded repeat ranged from (GCG)8 to (GCG)11. Ptosis and dysphagia were present in all examined cases. In 4 patients weakness of extraocular muscle was found and two of them experienced transient diplopia. Mild limb-girdle weakness was observed in 6 patients. Muscle biopsy performed in all cases showed myopathic changes with rare rimmed vacuoles. Strikingly, despite thorough examination on electron microscopy, intranuclear inclusions typical for OPMD were found only in one patient., Conclusions: Genetic testing is necessary to confirm the diagnosis of OPMD, especially in cases with ptosis and external ophthalmoparesis, which may be initially diagnosed as mitochondrial myopathy.

Multi-minicore disease (MmD) is a congenital myopathy morphologically defined by the multifocal lack of oxidative activity on light microscopy (LM) and multiple small zones of sarcomeric disorganization on electron microscopy (EM) as the main findings in muscle biopsy. We report on clinical and pathomorphological features of 17 patients diagnosed with multi-minicore myopathy at our department. Clinically, axial and proximal muscle weakness was the predominant distinguishing feature. Dysmorphic features such as high-arched palate and chest deformities were frequent findings. Limitation in cervical spine mobility was found in 4 cases. Most of our cases were slowly progressive but three fatal cases also occurred. Multifocal lack of oxidative activity was found in 16/22 biopsies on LM. Examination on EM enabled the final diagnosis of MmD in all cases. It is of special interest that in 3 patients fulfilling the criteria of pure congenital fibre type disproportion and in 2 cases of centronuclear myopathy, the findings of ultrastructural examination led us to a revised diagnosis of MmD. We postulate that all muscle biopsies with abnormal fibre proportion or centrally located nuclei as the only pathology on LM need to undergo careful EM evaluation to identify possible underlying multi-minicore disease.