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Filamin-A-interacting protein 1 (FILIP1) is a structural protein that is involved in neuronal and muscle function and integrity and interacts with FLNa and FLNc. Pathogenic variants in filamin-encoding genes have been linked to neurological disorders (FLNA) and muscle diseases characterized by myofibrillar perturbations (FLNC), but human diseases associated with FILIP1 variants have not yet been described. Here, we report on five patients from four unrelated consanguineous families with homozygous FILIP1 variants (two nonsense and two missense). Functional studies indicated altered stability of the FILIP1 protein carrying the p.[Pro1133Leu] variant. Patients exhibit a broad spectrum of neurological symptoms including brain malformations, neurodevelopmental delay, muscle weakness and pathology, and dysmorphic features. Electron and immunofluorescence microscopy on the muscle biopsy derived from the patient harbouring the homozygous p.[Pro1133Leu] missense variant revealed core-like zones of myofibrillar disintegration, autophagic vacuoles and accumulation of FLNc. Proteomic studies on the fibroblasts derived from the same patient showed dysregulation of a variety of proteins including FLNc and alpha-B-crystallin, a finding (confirmed by immunofluorescence) which is in line with the manifestation of symptoms associated with the syndromic phenotype of FILIP1opathy. The combined findings of this study show that the loss of functional FILIP1 leads to a recessive disorder characterized by neurological and muscular manifestations as well as dysmorphic features accompanied by perturbed proteostasis and myopathology.

Popeye domain containing protein 1 (POPDC1) is a highly conserved transmembrane protein essential for striated muscle function and homeostasis. Pathogenic variants in the gene encoding POPDC1 (BVES, Blood vessel epicardial substance) are causative for limb-girdle muscular dystrophy (LGMDR25), associated with cardiac arrhythmia. We report on four affected children (age 7-19 years) from two consanguineous families with two novel pathogenic variants in BVES c.457CT(p.Q153X) and c.578TG (p.I193S). Detailed analyses were performed on muscle biopsies from an affected patient of each family including immunofluorescence, electron microscopy and proteomic profiling. Cardiac abnormalities were present in all patients and serum creatine kinase (CK) values were variably elevated despite lack of overt muscle weakness. Detailed histological analysis of skeletal muscle, however indicated a myopathy with reduced sarcolemmal expression of POPDC1 accompanied by altered sarcolemmal and sarcoplasmatic dysferlin and Xin/XIRP1 abundance. At the electron microscopic level, the muscle fiber membrane was focally disrupted. The proteomic signature showed statistically significant dysregulation of 191 proteins of which 173 were increased and 18 were decreased. Gene ontology-term analysis of affected biological processes revealed - among others - perturbation of muscle fibril assembly, myofilament sliding, and contraction as well as transition between fast and slow fibers. In conclusion, these findings demonstrate that the phenotype of LGMDR25 is highly variable and also includes younger children with conduction abnormalities, no apparent muscular problems, and only mildly elevated CK values. Biochemical studies suggest that BVES mutations causing loss of functional POPDC1 can impede striated muscle function by several mechanisms.

The original version of this article unfortunately contained mistake. One of the author name was missspelled during revision and finalization of the manuscript. Dr. Kiran Polavarapu's surname "Polaparapu" should be spelled "Polavarapu". The original article has been corrected.

The small sample sizes inherent in rare and pediatric disease settings offer significant challenges for clinical trial design. In such settings, Bayesian adaptive trial methods can often pay dividends, allowing the sensible incorporation of auxiliary data and other relevant information to bolster that collected by the trial itself. Previous work has also included the use of one-arm trials augmented by the participants’ own natural history data, from which the future course of the disease in the absence of intervention can be predicted. Patient response can then be defined by the degree to which post-intervention observations are inconsistent with the predicted “natural” trajectory. While such trials offer obvious advantages in efficiency and ethical hazard (since they expose no new patients to a placebo, anathema to patients or their parents and caregivers), they can offer no protection against bias arising from the presence of any “placebo effect,” the tendency of patients to improve merely by being in the trial. In this paper, we investigate the impact of both static and transient placebo effects on one-arm responder studies of this type, as well as two-arm versions that incorporate a small concurrent placebo group but still borrow strength from the natural history data. We also propose more traditional Bayesian changepoint models that specify a parametric functional form for the patient’s post-intervention trajectory, which in turn allow quantification of the treatment benefit in terms of the model parameters, rather than semi-parametrically in terms of a response relative to some “null” model. We compare the operating characteristics of our designs in the context of an ongoing investigation of centronuclear myopathies (CNMs), a group of congenital neuromuscular diseases whose most common and severe form is X-linked, affecting approximately 1 in 50,000 newborn boys. Our results indicate our two-arm responder and changepoint methods can offer protection against placebo effects, improving power while protecting the trial’s Type I error rate. However, further research into innovative trial designs as well as ongoing dialog with regulatory authorities remain critically important in rare disease research.

Genes 13(5), 893 (2022). doi:10.3390/genes13050893 special issue: "Special Issue "Genetics of Motor Neuron Diseases" / Special Issue Editor: Christopher Grunseich, Guest Editor", Published by MDPI, Basel

X-linked myotubular myopathy (XLMTM) is a life-threatening rare neuromuscular disease, which is caused by pathogenic variants in the MTM1 gene. It has a large phenotypic heterogeneity, ranging from patients, who are able to walk independently to immobile patients who are only able to bring hand to mouth and depend on a respirator 24 hours a day every day. This suggests that ventilator requirements may not illustrate the full clinical picture of patients with XLMTM. At present, there is no curative therapy available, despite first promising results from ongoing gene therapy studies. In this study, we evaluated in detail the data from 13 German XLMTM patients, which was collected over a period of up to 20 years in our university hospital. We compared it to the international prospective longitudinal natural history study (NHS) data from 45 patients (containing 11 German patients). To highlight the broad phenotypic spectrum of the disease, we additionally focused on the clinical presentation of three cases at a glance. Comparing our data with the above mentioned natural history study, it appears the patients of the present German cohort seem to be more often severely affected, with higher frequency of non-ambulatory patients and patients on ventilation (and for longer time) and a higher proportion of patients needing a percutaneous endoscopic gastrostomy. Another key finding is a potential gap in time between first clinical presentation and final diagnosis, showing a need for patients to be treated in a specialized center for neuromuscular diseases.

The synthesis of cytochrome c oxidase 2 (SCO₂) gene encodes for a mitochondrial located metallochaperone essential for the synthesis of the cytochrome c oxidase (COX) subunit 2. Recessive mutations in SCO₂ have been reported in several cases with fatal infantile cardioencephalomyopathy with COX deficiency and in only four cases with axonal neuropathy. Here, we identified a homozygous pathogenic variant (c.361G > C; p.[Gly121Arg]) in SCO₂ in two brothers with isolated axonal motor neuropathy. To address pathogenicity of the amino acid substitution, biochemical studies were performed and revealed increased level of the mutant SCO₂-protein and dysregulation of COX subunits in leukocytes and moreover unraveled decrease of proteins involved in the manifestation of neuropathies. Hence, our combined data strengthen the concept of SCO₂ being causative for a very rare form of axonal neuropathy, expand its molecular genetic spectrum and provide first biochemical insights into the underlying pathophysiology.

CSDE1 encodes the cytoplasmic cold shock domain-containing protein E1 (CSDE1), which is highly conserved across species and functions as an RNA-binding protein involved in translationally coupled mRNA turnover. CSDE1 displays a bidirectional role: promoting and repressing the translation of RNAs but also increasing and decreasing the abundance of RNAs. Preclinical studies highlighted an involvement of CSDE1 in different forms of cancer. Moreover, CSDE1 is highly expressed in human embryonic stem cells and plays a role in neuronal migration and differentiation. A genome-wide association study suggested CSDE1 as a potential autism-spectrum disorder risk gene. A multicenter next generation sequencing approach unraveled likely causative heterozygous variants in CSDE1 in 18 patients, identifying a new autism spectrum disorder-related syndrome consisting of autism, intellectual disability, and neurodevelopmental delay. Since then, no further patients with CSDE1 variants have been reported in the literature. Here, we report a 9.5-year-old girl from a consanguineous family of Turkish origin suffering from profound delayed speech and motor development, moderate intellectual disability, neurologic and psychiatric symptoms as well as hypoplasia of corpus callosum and mildly reduced brain volume on brain magnetic resonance imaging associated with a recurrent de novo mutation in CSDE1 (c.367C > T; p.R123*) expanding the phenotypical spectrum associated with pathogenic CSDE1 variants. Funding: Andreas Roos received funding from The French Muscular Dystrophy Association (AFM-Téléthon) (grant 21644). Andreas Roos, Andrea Gangfuß, and Ulrike Schara-Schmidt also acknowledge funding in the framework of the NME-GPS project by the European Regional Development Fund (ERDF). Rita Horvath was supported by the European Research Council (309548), the Wellcome Investigator Award (109915/Z/15/Z), the Medical Research Council (UK) (MR/N025431/1), the Wellcome Trust Pathfinder Scheme (201064/Z/16/Z) and the Newton Fund (UK/Turkey, MR/N027302/1). Hanns Lochmüller receives support from the Canadian Institutes of Health Research (Foundation Grant FDN-167281), the Canadian Institutes of Health Research, and Muscular Dystrophy Canada (Network Catalyst Grant for NMD4C), the Canada Foundation for Innovation (CFI-JELF 38412), and the Canada Research Chairs program (Canada Research Chair in Neuromuscular Genomics and Health, 950-232279). AT is supported by the Horizon 2020 research and innovation program via grant 779257 “Solve-RD.” Sequencing and analysis were provided by the Broad Institute of MIT and Harvard Center for Mendelian Genomics (Broad CMG) and was funded by the National Human Genome Research Institute, the National Eye Institute, and the National Heart, Lung and Blood Institute grant UM1 HG008900 and in part by National Human Genome Research Institute grant R01 HG009141. Andreas Roos received funding from The French Muscular Dystrophy Association (AFM-Téléthon) (grant 21644). Andreas Roos, Andrea Gangfuß, and Ulrike Schara-Schmidt also acknowledge funding in the framework of the NME-GPS project by the European Regional Development Fund (ERDF). Rita Horvath was supported by the European Research Council (309548), the Wellcome Investigator Award (109915/Z/15/Z), the Medical Research Council (UK) (MR/N025431/1), the Wellcome Trust Pathfinder Scheme (201064/Z/16/Z), the Newton Fund (UK/Turkey, MR/N027302/1) and the Lily Foundation and the Evelyn Trust. Hanns Lochmüller receives support from the Canadian Institutes of Health Research (Foundation Grant FDN-167281), the Canadian Institutes of Health Research, and Muscular Dystrophy Canada (Network Catalyst Grant for NMD4C), the Canada Foundation for Innovation (CFI-JELF 38412), and the Canada Research Chairs program (Canada Research Chair in Neuromuscular Genomics and Health, 950-232279). AT is supported by the Horizon 2020 research and innovation program via grant 779257 “Solve-RD.” Sequencing and analysis were provided by the Broad Institute of MIT and Harvard Center for Mendelian Genomics (Broad CMG) and was funded by the National Human Genome Research Institute, the National Eye Institute, and the National Heart, Lung and Blood Institute grant UM1 HG008900 and in part by National Human Genome Research Institute grant R01 HG009141

Background: Presynaptic forms of congenital myasthenic syndromes (CMS) due to pathogenic variants in SLC18A3 impairing the synthesis and recycling of acetylcholine (ACh) have recently been described. SLC18A3 encodes the vesicular ACh transporter (VAChT), modulating the active transport of ACh at the neuromuscular junction, and homozygous loss of VAChT leads to lethality. Methods: Exome sequencing (ES) was carried out to identify the molecular genetic cause of the disease in a 5-year-old male patient and histological, immunofluorescence as well as electron- and CARS-microscopic studies were performed to delineate the muscle pathology, which has so far only been studied in VAChT-deficient animal models. Results: ES unraveled compound heterozygous missense and nonsense variants (c.315G>A, p.Trp105* and c.1192G>C, p.Asp398His) in SLC18A3. Comparison with already-published cases suggests a more severe phenotype including impaired motor and cognitive development, possibly related to a more severe effect of the nonsense variant. Therapy with pyridostigmine was only partially effective while 3,4 diaminopyridine showed no effect. Microscopic investigation of the muscle biopsy revealed reduced fibre size and a significant accumulation of lipid droplets. Conclusions: We suggest that nonsense variants have a more detrimental impact on the clinical manifestation of SLC18A3-associated CMS. The impact of pathogenic SLC18A3 variants on muscle fibre integrity beyond the effect of denervation is suggested by the build-up of lipid aggregates. This in turn implicates the importance of proper VAChT-mediated synthesis and recycling of ACh for lipid homeostasis in muscle cells. This hypothesis is further supported by the pathological observations obtained in previously published VAChT-animal models.

Neurological diseases affect 3-5% of children and, apart from cardiovascular diseases and cancer, represent the most prominent cause of morbidity and mortality in adults and particularly in the aged population of western Europe. Neuromuscular disorders are a subgroup of neurological diseases and often have a genetic origin, which leads to familial clustering. Despite the enormous progress in the analysis of the genome, such as by sequence analysis of coding regions of deoxyribonucleic acid or even the entire deoxyribonucleic acid sequence, in approximately 50% of the patients suffering from rare forms of neurological diseases the genetic cause remains unsolved. The reasons for this limited detection rate are presented in this article. If a treatment concept is available, under certain conditions this can have an impact on the adequate and early treatment of these patients. Considering neuromuscular disorders as a paradigm, this article reports on the advantages of the inclusion of next generation sequencing analysis-based DNA investigations as an omics technology (genomics) and the advantage of the integration with protein analyses (proteomics). A special focus is on the combination of genomics and proteomics in the sense of a proteogenomic approach in the diagnostics and research of these diseases. Along this line, this article presents a proteogenomic approach in the context of a multidisciplinary project aiming towards improved diagnostic work-up and future treatment of patients with neuromuscular diseases; "NMD-GPS: gene and protein signatures as a global positioning system in patients suffering from neuromuscular diseases".Neurologische Erkrankungen betreffen 3–5 % aller Kinder und nehmen bei Erwachsenen, insbesondere in der alternden Population Westeuropas, neben Herz‑/Kreislauf- und Tumorerkrankungen die häufigste Ursache für Morbidität und Mortalität ein. Neuromuskuläre Krankheitsbilder sind eine Untergruppe der neurologischen Erkrankungen und haben häufig eine genetische Ursache, was zu einer familiären Häufung führt. Trotz des enormen Fortschritts in der Analyse des Erbguts wie beispielsweise durch Sequenzanalysen der kodierenden Desoxyribonukleinsäureregionen oder der gesamten Desoxyribonukleinsäure bleibt die genetische Ursache bei ca. der Hälfte der Patienten, die an seltenen Formen neurologischer Erkrankungen leiden, ungeklärt. Gründe hierfür werden in diesem Artikel aufgeführt. Im Falle des Vorhandenseins von Therapiekonzepten kann dies unter Umständen einen Einfluss auf die frühzeitige und adäquate Behandlung der Patienten haben. Unter Betrachtung der neuromuskulären Erkrankungen als Paradigmen stellt dieser Artikel neben den Vorzügen des Einzugs der „Next-generation-sequencing“-Analyse-basierten DNA-Untersuchungen als eine Omics-Technologie („genomics“) zudem den Vorzug der Integration dieser mit Proteinanalysen („proteomics“) dar. Dabei wird ein besonderes Augenmerk auf die Kombination von Genomik und Proteomik in Sinne eines proteogenomischen Ansatzes bei der Diagnostik und Erforschung der Erkrankungen gelegt. In diesem Sinne wird im Rahmen dieses Artikels ein proteogenomischer Ansatz im Kontext eines multidisziplinären Projektes zur verbesserten Diagnostik und zukünftigen Therapie von Patienten mit neuromuskulären Erkrankungen vorgestellt; NME-GPS: Gen- und Protein-Signaturen als globales Positionsbestimmungssystem bei Patienten mit neuromuskulären Erkrankungen.

Amyotrophic lateral sclerosis (ALS) is a progressive, neurodegenerative disease of the lower and upper motor neurons with sporadic or hereditary occurrence. Age of onset, pattern of motor neuron degeneration and disease progression vary widely among individuals with ALS. Various cellular processes may drive ALS pathomechanisms, but a monogenic direct metabolic disturbance has not been causally linked to ALS. Here we show SPTLC1 variants that result in unrestrained sphingoid base synthesis cause a monogenic form of ALS. We identified four specific, dominantly acting SPTLC1 variants in seven families manifesting as childhood-onset ALS. These variants disrupt the normal homeostatic regulation of serine palmitoyltransferase (SPT) by ORMDL proteins, resulting in unregulated SPT activity and elevated levels of canonical SPT products. Notably, this is in contrast with SPTLC1 variants that shift SPT amino acid usage from serine to alanine, result in elevated levels of deoxysphingolipids and manifest with the alternate phenotype of hereditary sensory and autonomic neuropathy. We custom designed small interfering RNAs that selectively target the SPTLC1 ALS allele for degradation, leave the normal allele intact and normalize sphingolipid levels in vitro. The role of primary metabolic disturbances in ALS has been elusive; this study defines excess sphingolipid biosynthesis as a fundamental metabolic mechanism for motor neuron disease.

Intellectual disability (ID) has an estimated prevalence of 1.5%-2%. Whole exome sequencing (WES) studies have identified a multitude of novel causative gene defects and have shown that sporadic ID cases result from de novo mutations in genes associated with ID. Here, we report on a 10-year-old girl, who has been regularly presented in our neuropediatric and genetic outpatient clinic. A median cleft palate and a heart defect were surgically corrected in infancy. Apart from ID, she has behavioral anomalies, muscular hypotonia, scoliosis, and hypermobile joints. The facial phenotype is characterized by arched eyebrows, mildly upslanting long palpebral fissures, prominent nasal tip, and large, protruding ears. Trio WES revealed a de novo missense variant in MEIS2 (c.998G>A; p.Arg333Lys). Haploinsufficiency of MEIS2 had been discussed as the most likely mechanism of the microdeletion 5q14-associated complex phenotype with ID, cleft palate, and heart defect. Recently, four studies including in total 17 individuals with intragenic MEIS2 variants were reported. Here we present the evolution of the clinical phenotype and compare with the data of known individuals.

Sarcoglycanopathies comprise four subtypes of autosomal recessive limb-girdle muscular dystrophies (LGMDR3, LGMDR4, LGMDR5 and LGMDR6) that are caused, respectively, by mutations in the SGCA, SGCB, SGCG and SGCD genes. In 2016, several clinicians involved in the diagnosis, management and care of patients with LGMDR3–6 created a European Sarcoglycanopathy Consortium. The aim of the present study was to determine the clinical and genetic spectrum of a large cohort of patients with sarcoglycanopathy in Europe. This was an observational retrospective study. A total of 33 neuromuscular centres from 13 different European countries collected data of the genetically confirmed patients with sarcoglycanopathy followed-up at their centres. Demographic, genetic and clinical data were collected for this study. Data from 439 patients from 13 different countries were collected. Forty-three patients were not included in the analysis because of insufficient clinical information available. A total of 159 patients had a confirmed diagnosis of LGMDR3, 73 of LGMDR4, 157 of LGMDR5 and seven of LGMDR6. Patients with LGMDR3 had a later onset and slower progression of the disease. Cardiac involvement was most frequent in LGMDR4. Sixty per cent of LGMDR3 patients carried one of the following mutations, either in a homozygous or heterozygous state: c.229C>T, c.739G>A or c.850C>T. Similarly, the most common mutations in LMGDR5 patients were c.525delT or c.848G>A. In LGMDR4 patients the most frequent mutation was c.341C>T. We identified onset of symptoms before 10 years of age and residual protein expression lower than 30% as independent risk factors for losing ambulation before 18 years of age, in LGMDR3, LGMDR4 and LGMDR5 patients. This study reports clinical, genetic and protein data of a large European cohort of patients with sarcoglycanopathy. Improving our knowledge about these extremely rare autosomal recessive forms of LGMD was helped by a collaborative effort of neuromuscular centres across Europe. Our study provides important data on the genotype-phenotype correlation that is relevant for the design of natural history studies and upcoming interventional trials in sarcoglycanopathies.

Neue Therapieansatze haben den Ubergang vom theoretischen Konzept zu randomisierten, kontrollierten Studien und nun erstmals zu einer medikamentosen Behandlung der proximalen spinalen Muskelatrophie (SMA) bei Patienten vollzogen. Masgebend fur den Therapieerfolg sind der fruhzeitige Einsatz der medikamentosen Behandlung und damit die Entdeckung der Erkrankung in einem fruhen Stadium, sodass die Einfuhrung eines flachendeckenden Neugeborenenscreenings fur die SMA notwendig erscheint.

ObjectivesBecause X-linked myotubular myopathy (XLMTM) is a rare neuromuscular disease caused by mutations in the MTM1 gene with a large phenotypic heterogeneity, to ensure clinical trial readiness, it was mandatory to better quantify disease burden and determine best outcome measures.MethodsWe designed an international prospective and longitudinal natural history study in patients with XLMTM and assessed muscle strength and motor and respiratory functions over the first year of follow-up. The humoral immunity against adeno-associated virus serotype 8 was also monitored.ResultsForty-five male patients aged 3.5 months to 56.8 years were enrolled between May 2014 and May 2017. Thirteen patients had a mild phenotype (no ventilation support), 7 had an intermediate phenotype (ventilation support less than 12 hours a day), and 25 had a severe phenotype (ventilation support 12 or more hours a day). Most strength and motor function assessments could be performed even in very weak patients. Motor Function Measure 32 total score, grip and pinch strengths, and forced vital capacity, forced expiratory volume in the first second of exhalation, and peak cough flow measures discriminated the 3 groups of patients. Disease history revealed motor milestone loss in several patients. Longitudinal data on 37 patients showed that the Motor Function Measure 32 total score significantly decreased by 2%. Of the 38 patients evaluated, anti–adeno-associated virus type 8 neutralizing activity was detected in 26% with 2 patients having an inhibitory titer >1:10.ConclusionsOur data confirm that XLMTM is slowly progressive for male survivors regardless of their phenotype and provide outcome validation and natural history data that can support clinical development in this population.ClinicalTrials.gov identifierNCT02057705.

Recessive variants in WASHC4 are linked to intellectual disability complicated by poor language skills, short stature, and dysmorphic features. The protein encoded by WASHC4 is part of the Wiskott-Aldrich syndrome protein and SCAR homolog family, co-localizes with actin in cells, and promotes Arp2/3-dependent actin polymerization in vitro. Functional studies in a zebrafish model suggested that WASHC4 knockdown may also affect skeletal muscles by perturbing protein clearance. However, skeletal muscle involvement has not been reported so far in patients, and precise biochemical studies allowing a deeper understanding of the molecular etiology of the disease are still lacking. Here, we report two siblings with a homozygous WASHC4 variant expanding the clinical spectrum of the disease and provide a phenotypical comparison with cases reported in the literature. Proteomic profiling of fibroblasts of the WASHC4-deficient patient revealed dysregulation of proteins relevant for the maintenance of the neuromuscular axis. Immunostaining on a muscle biopsy derived from the same patient confirmed dysregulation of proteins relevant for proper muscle function, thus highlighting an affliction of muscle cells upon loss of functional WASHC4. The results of histological and coherent anti-Stokes Raman scattering microscopic studies support the concept of a functional role of the WASHC4 protein in humans by altering protein processing and clearance. The proteomic analysis confirmed key molecular players in vitro and highlighted, for the first time, the involvement of skeletal muscle in patients. © 2021 The Authors. The Journal of Pathology published by John Wiley & Sons, Ltd. on behalf of The Pathological Society of Great Britain and Ireland. This study was supported by four authors of this publication who are members of the European Reference Network for Neuromuscular Diseases – Project ID No 870177. This study was supported also by the ‘Ministerium für Kultur und Wissenschaft des Landes Nordrhein-Westfalen’, the ‘Regierenden Bürgermeister von Berlin – Senatskanzlei Wissenschaft und Forschung’, and the ‘Bundesministerium für Bildung und Forschung’, also in form of the Leibniz Research Cluster (grant number 031A360E). This work was also supported by a grant from the French Muscular Dystrophy Association (AFM-Téléthon) (#21466) to AR. RH was supported by the European Research Council (309548), a Wellcome Investigator Award (109915/Z/15/Z), the Medical Research Council (UK) (MR/N025431/1), the Wellcome Trust Pathfinder Scheme (201064/Z/16/Z) and the Newton Fund (UK/Turkey, MR/N027302/1). HL receives support from the Canadian Institutes of Health Research (Foundation Grant FDN-167281), the Canadian Institutes of Health Research and Muscular Dystrophy Canada (Network Catalyst Grant for NMD4C), the Canada Foundation for Innovation (CFI-JELF 38412), and the Canada Research Chairs program (Canada Research Chair in Neuromuscular Genomics and Health, 950-232279). Parts of this study were financed within the framework of the NME-GPS project by the European Regional Development Fund (ERDF). AT is supported by the Horizon 2020 research and innovation program via grant 779257 ‘Solve-RD’. Sequencing and analysis were provided by the Broad Institute of MIT and Harvard Center for Mendelian Genomics (Broad CMG) and were funded by the National Human Genome Research Institute, the National Eye Institute, and the National Heart, Lung and Blood Institute grant UM1 HG008900, and in part by National Human Genome Research Institute grant R01 HG009141