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Agrin-mediated neuromuscular junction (NMJ) morphological alterations is one of the main pathogeneses of sarcopenia. The aim of this study was to observe the changes in serum agrin in patients with different degrees of sarcopenia and the alterations in Agrin receptors in human skeletal muscle with age. A total of 236 elderly subjects were enrolled and categorized into nonsarcopenia, possible sarcopenia, sarcopenia, and severe sarcopenia groups. Serum levels of the C-terminal Agrin fragment were quantified using an Enzyme-Linked Immunosorbent Assay (ELISA) kit. In addition, in a distinct and smaller exploratory subgroup ( Show less

Genome-wide studies of differential DNA methylation often focus on its role in turning transcription on or off. Here we report some atypical epigenetic/transcription relationships for 92 genes that are highly and preferentially expressed in primary human myoblasts relative to heterologous cell cultures. We compared methylomes and myoblast-specific differentially methylated regions (DMRs) with methylomes, chromatin profiles, and transcriptomes for many different cell populations. We found that myoblast-associated promoter hypomethylation was unusually prevalent among the 92 myoblast-preferential genes. Sometimes this promoter hypomethylation was seen as a myoblast-associated extension of their constitutively unmethylated region at a CpG island. All 92 genes showed some myoblast-specific hypomethylation, including 32 genes at tissue-specific super-enhancers or broad H3K4-trimethylated promoters. Myoblast hypermethylated DMRs were also associated with almost half of the myoblast-preferential genes. These hypermethylated DMRs were often in intragenic locations embedded in H3K36-trimethylated chromatin in myoblasts. Our analysis suggests that some of the hypermethylated DMRs repress cryptic, alternative, or adjacent promoters. Myoblast hypermethylated DMRs may also downmodulate expression in myoblasts to avoid yet higher RNA levels found in adult or fetal skeletal muscle tissue. The epigenetic insights that were obtained can help elucidate the transcription regulation of some of these genes (e.g., Show less

Congenital myasthenic syndromes (CMS) are often underdiagnosed due to phenotypic overlap with other neuromuscular disorders. Limited epidemiological data and low awareness hinder early diagnosis, which is key for effective treatment. Early recognition of CMS is important as symptomatic treatments often specific for genetic subtypes exist and emerging therapies are in the pipeline. This study aims to estimate the prevalence of genetically confirmed CMS in the United Kingdom and explore geographical variations. Prevalence was calculated as of 31 December 2023, including genetically confirmed CMS patients residing in the United Kingdom and known to be alive. Patients with missing geographic or living status data were excluded. Prevalence was estimated overall and compared between UK regions served by a highly specialized neuromuscular service (hsNMS) and those without such services (non-hsNMS). A cohort of 442 genetically confirmed CMS patients was identified. CHRNE deficiency, DOK7, RAPSN were the most common subtypes. The UK prevalence was 6.5 cases per million overall and 8.5 cases per million in the pediatric population. The overall prevalence was statistically higher in hsNMS (8.8 cases per million) compared to non-hsNMS regions (5.9 cases per million). Homozygous patients had a more clustered distribution particularly around urban area. Our results suggest there is likely underdiagnosis of CMS in many areas of the United Kingdom and hsNMS may play an important diagnostic role. Variations may also be related to other cultural clustering and founder effects. Further research should explore how healthcare access, ethnicity, and consanguinity contribute to regional variation and diagnostic rates. Show less

Male infertility affects approximately one in seven couples worldwide. Prenatal cadmium (Cd) exposure has been shown to affect offspring phenotypes and increase susceptibility to diseases later in life. However, the effects of prenatal Cd exposure on multi-generational offspring fertility and the mechanisms remain unknown. A novel murine multi-generational (F1-F3 offspring) male subfertility model induced by prenatal Cd exposure was developed. The levels of testosterone and steroidogenic enzymes were also lower in these offspring's testes. The ubiquitin-dependent degradation of NR4A1, the upstream transcription factor regulating steroidogenic enzymes, was enhanced across generations upon prenatal Cd exposure. After treatment with MG132, an inhibitor of the ubiquitin-proteasome system, the levels of NR4A1 and steroidogenic enzymes were higher in offspring testes with prenatal Cd exposure. Based on the analysis of the UbiBrowser database and testicular global transcriptome, RAPSN was identified as a novel ubiquitin E3 ligase containing the RING-H2_Rapsyn domain that mediates multi-generational testicular NR4A1 ubiquitination. m Show less

Gastric adenocarcinoma with enteroblastic differentiation (GAED) is a rare entity with worse prognosis compared to conventional gastric adenocarcinomas. Its histological characteristics are fetal gut-like architecture and tumor cells with cytoplasmic clearing, as well as positive immunohistochemical reaction to at least one of the enteroblastic markers. Hereby, we present a case of GAED with neuroendocrine marker positivity, with whole-exome sequencing (WES), and an updated literature review. A 68-year-old woman presented at the general practitioner with abdominal pain. Abdominal ultrasound described gastric wall thickening raising suspicion of gastric cancer; thus, gastroscopy was performed, and biopsy samples were taken, which confirmed malignancy. Neoadjuvant systemic chemotherapy was initiated, and total gastrectomy was performed. Microscopically, pleomorphic polygonal cells were visible with clear cytoplasm and high-grade cellular atypia. Alcian blue and PAS stains demonstrated positivity for acidic and neutral mucins. P53 IHC was negative, indicative of null-phenotype, while Syntaxin-1 and Chromogranin showed focal positivity. SALL4 and Glypican 3 were positive; however, AFP displayed only minimal, uncertain positivity. The Ki67 labeling index was 70%. Due to the morphological and immunohistochemical characteristics, the tumor was concluded as GAED with neuroendocrine marker positivity. WES was carried out revealing 4 pathogenic, including TP53, KLHL7, RAPSN, and ACTA1, and 3 likely pathogenic mutations, encompassing PNKP, HNF1A, and ADNP. GAED is a rare subtype of gastric adenocarcinomas, representing 0.3-5.4% of all cases, and has an unclarified etiology. Our WES results identified new pathogenic and likely pathogenic mutations. From a differential diagnostic point of view, hepatoid adenocarcinoma and the possibility of metastatic origin have to be excluded. Show less

Congenital Myasthenic Syndromes (CMS) are a group of inherited disorders characterised by fatigable muscle weakness. There are currently no validated outcome measures in CMS. We conducted a prospective exploratory observational study in 49 CMS patients. The primary aim was to explore relevant and reliable outcome measures for assessing and monitoring change. Assessments included Quantitative Myasthenia Gravis score, Myasthenia Gravis Activities of Daily Living, six-minute-walk-test and sit to stand in one minute, in addition to others. Patients were seen 2-4 times over a 2-year period. Median age was 25.5 (range 1-72) years. Subtypes included AChR-deficiency (n = 15), AGRN-DOK7 clustering complex (n = 15), RAPSN (n = 6), COLQ (n = 5), others (n = 8). Ptosis was highest in AChR-deficiency and limb fatigue was highest in AGRN-DOK7 and COLQ. Median sit to stand in one minute was 22 (range 6-45), median total distance walked in six-minute-walk-test was 434 metres (range 0-711 m). A correlation was noted between sit to stand and six-minute-walk-test (R² = 0.291, p-value <0.001) and between total Quantitative Myasthenia Gravis and Myasthenia Gravis Activities of Daily Living scores (R² = 0.2851, p-value <0.001). This is the first study exploring the use of outcome measures in a CMS population, highlighting the variability in fatigue across CMS subtypes and the limitations of outcome measures validated in myasthenia gravis for CMS. Show less

Myasthenia gravis (MG) is a disorder of the neuromuscular junction, typically associated with autoantibodies (Abs) that impair neuromuscular transmission. However, approximately 10% of cases are seronegative. Emerging evidence suggests that seronegative MG (SNMG) may be mimicked by hereditary conditions, particularly congenital myasthenic syndromes (CMSs), which require different treatments. In this study, we aimed to determine the proportion of CMS among patients diagnosed with SNMG. We used whole-exome sequencing (WES) in adult patients (aged ≥18 years) diagnosed with SNMG who were enrolled at 3 Austrian tertiary neuromuscular centers between August 2022 and January 2024. Genetic testing was conducted in individuals who remained seronegative after comprehensive serologic testing to exclude Abs against (clustered) acetylcholine receptors, muscle-specific kinase, lipoprotein receptor-related protein 4, and voltage-gated calcium channels. Moreover, we aimed to analyze clinical and demographic factors associated with the likelihood of receiving a molecular diagnosis. A total of 50 patients with SNMG (35 [70%] female) were referred for exome-based genetic screening. The median age at disease onset was 35 years (interquartile range 24.0-46.0 years). Seven patients (14%) were genetically diagnosed with CMS through WES (4 with Our findings provide evidence that a considerable proportion of patients diagnosed with SNMG have an underlying hereditary etiology. Notably, a (subjective) response to immunotherapies does not exclude a molecular CMS diagnosis. In conclusion, offering genetic testing to seronegative patients with myasthenic syndromes may have profound therapeutic implications. Show less

This study aims to identify BMI-associated genes by integrating aggregated summary information from different omics data. We conducted a meta-analysis to leverage information from a genome-wide association study (n = 339 224), a transcriptome-wide association study (n = 5619), and an epigenome-wide association study (n = 3743). We prioritized the significant genes with a machine learning-based method, netWAS, which borrows information from adipose tissue-specific interaction networks. We also used the brain-specific network in netWAS to investigate genes potentially involved in brain-adipose interaction. We identified 195 genes that were significantly associated with BMI through meta-analysis. The netWAS analysis narrowed down the list to 21 genes in adipose tissue. Among these 21 genes, six genes, including FUS, STX4, CCNT2, FUBP1, NDUFS3, and RAPSN, were not reported to be BMI-associated in PubMed or GWAS Catalog. We also identified 11 genes that were significantly associated with BMI in both adipose and whole brain tissues. This study integrated three types of omics data and identified a group of genes that have not previously been reported to be associated with BMI. This strategy could provide new insights for future studies to identify molecular mechanisms contributing to BMI regulation. Show less

Congenital myasthenic syndromes (CMS) are clinically and genetically heterogeneous diseases caused by mutations affecting neuromuscular transmission. Even if the first symptoms mainly occur during childhood, adult neurologists must confront this challenging diagnosis and manage these patients throughout their adulthood. However, long-term follow-up data from large cohorts of CMS patients are lacking, and the long-term prognosis of these patients is largely unknown. We report the clinical features, diagnostic difficulties, and long-term prognosis of a French nationwide cohort of 235 adult patients with genetically confirmed CMS followed in 23 specialized neuromuscular centres. Data were retrospectively analysed. Of the 235 patients, 123 were female (52.3%). The diagnosis was made in adulthood in 139 patients, 110 of whom presented their first symptoms before the age of 18. Mean follow-up time between first symptoms and last visit was 34 years [standard deviation (SD) = 15.1]. Pathogenic variants were found in 19 disease-related genes. CHRNE-low expressor variants were the most common (23.8%), followed by variants in DOK7 (18.7%) and RAPSN (14%). Genotypes were clustered into four groups according to the initial presentation: ocular group (CHRNE-LE, CHRND, FCCMS), distal group (SCCMS), limb-girdle group (RAPSN, COLQ, DOK7, GMPPB, GFPT1), and a variable-phenotype group (MUSK, AGRN). The phenotypical features of CMS did not change throughout life. Only four genotypes had a proportion of patients requiring intensive care unit admission that exceeded 20%: RAPSN (54.8%), MUSK (50%), DOK7 (38.6%) and AGRN (25.0%). In RAPSN and MUSK patients most ICU admissions occurred before age 18 years and in DOK7 and AGRN patients at or after 18 years of age. Different patterns of disease course (stability, improvement and progressive worsening) may succeed one another in the same patient throughout life, particularly in AGRN, DOK7 and COLQ. At the last visit, 55% of SCCMS and 36.3% of DOK7 patients required ventilation; 36.3% of DOK7 patients, 25% of GMPPB patients and 20% of GFPT1 patients were wheelchair-bound; most of the patients who were both wheelchair-bound and ventilated were DOK7 patients. Six patients died in this cohort. The positive impact of therapy was striking, even in severely affected patients. In conclusion, even if motor and/or respiratory deterioration could occur in patients with initially moderate disease, particularly in DOK7, SCCMS and GFPT1 patients, the long-term prognosis for most CMS patients was favourable, with neither ventilation nor wheelchair needed at last visit. CHRNE-LE patients did not worsen during adulthood and RAPSN patients, often severely affected in early childhood, subsequently improved. Show less

Congenital myasthenic syndromes (CMSs) are genetic disorders affecting motor function with variable symptoms. RAPSN-related CMS, caused by mutations in the RAPSN gene, leads to muscle weakness. Accurate diagnosis is essential for proper management. This study aims to analyze six Iranian families affected by RAPSN-CMS, focusing on clinical manifestations, genetic variants, treatment response, and outcomes. Clinical assessments, genetic analysis, and whole-exome sequencing were performed on the six families to identify RAPSN gene mutations. The study examined symptoms, disease severity, age of onset, treatment response, and outcomes. Treatment with pyridostigmine and salbutamol was given to assess its effectiveness. Three homozygous known variants in RAPSN gene were identified: c.491G > A in three families, c.264 C > A in two families, and c.-210 A > G in one family. Clinical assessments showed diversity in symptoms and treatment responses. Pyridostigmine and salbutamol treatment improved symptoms and quality of life. This study highlights the significance of molecular diagnosis for RAPSN-related congenital myasthenic syndromes (CMS) in Iran, marking the first comprehensive genetic analysis in the region. The identification of specific pathogenic variants underscores the unique genetic landscape of local patients. Furthermore, our long-term follow-up revealed variable treatment responses, emphasizing the need for personalized care strategies. The clinical variability among patients with identical mutations necessitates a multidisciplinary approach for effective management. By enhancing genetic awareness and refining follow-up methods, we aim to improve diagnosis accuracy and interventions, fostering better outcomes for affected families in the Iranian population. Show less

Congenital myasthenic syndrome is a heterogeneous group of inherited neuromuscular transmission disorders. Variants in RAPSN are a common cause of CMS, accounting for approximately 14%-27% of all CMS cases. Whether preimplantation genetic testing for monogenic disease (PGT-M) could be used to prevent the potential birth of CMS-affected children is unclear. Application of WES (whole-exome sequencing) for carrier testing and guidance for the PGT-M in the absence of a genetically characterized index patient as well as assisted reproductive technology were employed to prevent the occurrence of birth defects in subsequent pregnancy. The clinical phenotypes of stillborn fetuses were also assessed. The family carried two likely pathogenic variants in RAPSN(NM₀₀₅₀₅₅.5): c.133G>A (p.V45M) and c.280G>A (p.E94K). And the potential birth of CMS-affected child was successfully prevented, allowing the family to have offspring devoid of disease-associated variants and exhibiting a normal phenotype. This report constitutes the first documented case of achieving a CMS-free offspring through PGT-M in a CMS-affected family. By broadening the known variant spectrum of RAPSN in the Chinese population, our findings underscore the feasibility and effectiveness of PGT-M for preventing CMS, offering valuable insights for similarly affected families. Show less

Congenital myasthenic syndromes (CMS) are a group of genetic disorders characterized by impaired neuromuscular transmission. CMS typically present at a young age with fatigable muscle weakness, often with an abnormal response after repetitive nerve stimulation (RNS). Pharmacologic treatment can improve symptoms, depending on the underlying defect. Prevalence is likely underestimated. This study reports on patients with CMS followed in Belgium in 2022. Data were gathered retrospectively from the medical charts. Only likely pathogenic and pathogenic variants were included in the analysis. We identified 37 patients, resulting in an estimated prevalence of 3.19 per 1,000,000. The patients harbored pathogenic variants in CHRNE, RAPSN, DOK7, PREPL, CHRNB1, CHRNG, COLQ, MUSK, CHRND, GFPT1, and GMPPB. CHRNE was the most commonly affected gene. Most patients showed disease onset at birth, during infancy, or during childhood. Symptom onset was at adult age in seven patients, caused by variants in CHRNE, DOK7, MUSK, CHRND, and GMPPB. Severity and distribution of weakness varied, as did the presence of respiratory involvement, feeding problems, and extraneuromuscular manifestations. RNS was performed in 23 patients of whom 18 demonstrated a pathologic decrement. Most treatment responses were predictable based on the genotype. This is the first pooled characterization of patients with CMS in Belgium. We broaden the phenotypical spectrum of pathogenic variants in CHRNE with adult-onset CMS. Systematically documenting larger cohorts of patients with CMS can aid in better clinical characterization and earlier recognition of this rare disease. We emphasize the importance of establishing a molecular genetic diagnosis to tailor treatment choices. Show less

Congenital myasthenic syndromes (CMS) are rare, heterogeneous, and often treatable genetic disorders depending on the underlying molecular defect. We performed a detailed clinical evaluation of seven patients from five unrelated families. Exome sequencing was performed on five index patients. Clinically significant variants were identified in four CMS disease-causing genes: COLQ (3/7), CHRNE (2/7), DOK7 (1/7), and RAPSN (1/7). We identified two novel variants, c.930₉₃₃delCATG in DOK7 and c.1016₁₀₃₂ + 2dup in CHRNE . A common pathogenic variant, c.955-2A>C, has been identified in COLQ -related CMS patients. Homozygosity mapping of this COLQ variant in patients from two unrelated families revealed that it was located in a common homozygous region of 3.2 Mb on chromosome 3 and was likely to be inherited from a common ancestor. Patients with COLQ variants had generalized muscle weakness, those with DOK7 and RAPSN variants had limb-girdle weakness, and those with CHRNE variants had predominant ocular weakness. Patients with COLQ and DOK7 variants showed improvement with salbutamol and CHRNE with pyridostigmine therapy. This study expands the mutational spectrum and adds a small but significant cohort of CMS patients from India. We also reviewed the literature to identify genetic subtypes of CMS in India. Show less

Congenital myasthenic syndromes (CMSs) and primary mitochondrial myopathies (PMMs) can present with ptosis, external ophthalmoplegia, and limb weakness. Our method involved the description of three cases of CMS that were initially characterized as probable PMM. All patients were male and presented with ptosis and/or external ophthalmoplegia at birth, with proximal muscle weakness and fatigue on physical exertion. After normal repetitive nerve stimulation (RNS) studies performed on facial muscles, a muscle biopsy (at a median age of 9) was performed to rule out congenital myopathies. In all three cases, the biopsy findings (COX-negative fibers or respiratory chain defects) pointed to PMM. They were referred to our neuromuscular unit in adulthood to establish a genetic diagnosis. However, at this time, fatigability was evident in the physical exams and RNS in the spinal accessory nerve showed a decremental response in all cases. Targeted genetic studies revealed pathogenic variants in the Early identification of CMS is essential as medical treatment can provide clear benefits. Its diagnosis can be challenging due to phenotypic overlap with other debilitating disorders. Thus, a high index of suspicion is necessary to guide the diagnostic strategy. Show less

Background Congenital myasthenic syndromes (CMS) are a group of hereditary diseases of the neuromuscular junction. CMS are extremely rare diseases that cause hypotonia; however, scoliosis may theoretically be helpful in early diagnosis of CMS. The objective of this study was to emphasize the clinical features of the patients we followed up with the diagnosis of CMS and demonstrate that scoliosis is an important finding in the diagnosis of CMS in the presence of hypotonia/weakness. Materials and methods In this retrospective study, data were retrieved by examining the digital files of the patients who presented to Aydın Maternity and Children's Hospital and Elazığ Fethi Sekin City Hospital Pediatric Neurology Clinics between 2018 and 2023. The diagnosis of CMS was strongly supported by a combination of clinical characteristics, neurophysiological studies, genetic tests, AChR antibodies, and serum creatine kinase measurement. The presence of scoliosis was evaluated by an orthopedics and traumatology specialist. Results Eleven CMS patients with accompanying scoliosis were included in the study. The mean age of the patients was 69.4±39.28 months. The age of the patients at the time of diagnosis was 42.7±35.19 months. Among the patients, eight were males (72.7%), and three were females (27.2%). Seven patients (63.6%) had COLQ mutations. Electromyography was conducted on eight patients, with one of them showing no pathological findings, while seven exhibited decremental responses. All patients had ptosis, while six (54.5%) had bulbar signs. Ten patients (90.9%) had weakness. Nine patients (81.8%) experienced frequent recurrent lower respiratory tract infections. Both the patient with CHAT mutation and RAPSN mutation had arthrogryposis. Conclusion In this study, CMS stands out as an essential consideration in the differential diagnosis, particularly when scoliosis accompanies early-onset muscle weakness. Show less

In recent years, numerous studies have confirmed that chronic stress is closely related to the development of cancer. Our previous research showed that high levels of stress hormones secreted in the body during chronic stress could inhibit the cancer-killing activity of granulocytes, which could further promote the development of cancer. Therefore, reversing the immunosuppressive effect of stress hormones on granulocytes is an urgent problem in clinical cancer treatment. Here, we selected noradrenaline (NA) as a representative stress hormone. After screening many traditional Chinese herbal medicine active ingredients, a promising compound, ginsenoside Rg1, attracted our attention. We verified the immunoprotective effect of ginsenoside Rg1 on granulocytes In future clinical treatments, ginsenoside Rg1 may be used as an adjuvant agent for cancer treatment to alleviate chronic stress-induced adverse events in cancer patients. Show less

Respiratory problems are a major cause of morbidity and mortality in patients with congenital myasthenic syndromes, a rare heterogeneous group of neuromuscular disorders caused by genetic defects impacting the structure and function of the neuromuscular junction. Recurrent, life-threatening episodic apnoea in early infancy and childhood and progressive respiratory failure requiring ventilation are features of certain genotypes of congenital myasthenic syndromes. Robb Show less

We here present the case of a patient with a congenital myasthenic syndrome (CMS) due to pathogenic variants in the RAPSN gene. During childhood he experienced recurrent episodes of respiratory failure during respiratory infections. This and other cases were reported as isolated dystrophy of the diaphragmatic musculature. In adulthood, whole exome sequencing revealed two heterozygous pathogenic variants in the RAPSN gene. This led to the revision of the diagnosis to rapsyn CMS11 (OMIM:616326, MONDO:0014588). EMG, muscle ultrasound and the revision of muscle biopsies taken in childhood support this diagnosis. After the revision of the diagnosis, treatment with pyridostigmine was started. This resulted in a reduction of fatigability and an improvement in functional abilities and quality of life. Show less

Congenital myasthenic syndromes (CMS) are a heterogeneous group of disorders caused by genetic defects resulting in impaired neuromuscular transmission. Although effective treatments are available, CMS is probably underdiagnosed, and systematic clinico-genetic investigations are warranted. We used a nationwide approach to collect Austrian patients with genetically confirmed CMS. We provide a clinical and molecular characterization of this cohort and aimed to ascertain the current frequency of CMS in Austria. Twenty-eight cases with genetically confirmed CMS were identified, corresponding to an overall prevalence of 3.1 per million (95% CI 2.0-4.3) in Austria. The most frequent genetic etiology was CHRNE (n = 13), accounting for 46.4% of the cohort. Within this subgroup, the variant c.1327del, p.(Glu443Lysfs*64) was detected in nine individuals. Moreover, causative variants were found in DOK7 (n = 4), RAPSN (n = 3), COLQ (n = 2), GMPPB (n = 2), CHAT (n = 1), COL13A1 (n = 1), MUSK (n = 1) and AGRN (n = 1). Clinical onset within the first year of life was reported in one half of the patients. Across all subtypes, the most common symptoms were ptosis (85.7%), lower limb (67.9%), upper limb (60.7%) and facial weakness (60.7%). The majority of patients (96.4%) received specific treatment, including acetylcholinesterase inhibitors in 20, adrenergic agonists in 11 and 3,4-diaminopyridine in nine patients. Our study presents the first systematic characterization of individuals with CMS in Austria, providing prevalence estimates and genotype-phenotype correlations that may help to improve the diagnostic approach and patient management. Show less

Congenital myasthenic syndromes (CMS) are a heterogeneous group of disorders characterized by impaired neuromuscular signal transmission due to germline pathogenic variants in genes expressed at the neuromuscular junction (NMJ). A total of 35 genes have been reported in CMS ( Show less

Congenital myasthenic syndromes (CMS) are composed of numerous hereditary disorders involving genetic mutations in proteins essential to the integrity of neuromuscular transmission. The symptoms of CMS vary according to the age at onset of symptoms, and the type and severity of muscle weakness. Effective treatment and genetic counseling depend upon the underlying pathogenic molecular mechanism and subtype of CMS. A retrospective and cross-sectional study was performed with 16 patients with a genetically confirmed diagnosis of CMS to share our experience with clinical symptoms, demographic data, genetic variants, and treatments applied. Sixteen patients with a specific CMS genetic diagnosis (three novel mutations) were identified, including CHRNE (n = 7), DOK7 (n = 2), AGRN (n = 2), RAPSN (n = 1), CHRNA1 (n = 1), CHRNB1 (n = 1), CHAT (n = 1), and SCN4A (n = 1). Age at onset of symptoms ranged from the neonatal period to 12 years. Genetic diagnosis was confirmed between the ages of three months and 17 years. A significant delay was determined between the onset of symptoms and genetic diagnosis of the disease. This study highlights the importance of genetic testing in CMS. Due to the rarity of CMS, more cases will be recognized and reported as the use of laboratory and genetic testing accelerates. We hope that our experience will grow and contribute further to the literature as clinical follow-up and treatment increase. Show less

Congenital myasthenic syndromes (CMS) are a group of heterogeneous diseases of the neuromuscular junction. We report electrodiagnostic testing (EDX) and genetic findings in a series of 120 CMS patients tested with a simple non-invasive EDX workup with surface recording of CMAPs and 3Hz repetitive nerve stimulation of accessory, radial and deep fibular nerves. Five ENMG phenotypes were retrieved based on the presence or not of R-CMAPs and the distribution pattern of decremental CMAP responses which significantly correlated with genetic findings (p <0.00001). R-CMAPs were found in all COLQ-mutated patients (CMS1A) and Slow Channel CMS (SCCMS) (CMS1B). CMS1A exhibited greater decrements in accessory nerve RNS than CMS1B. Patients without R-CMAPs were classified into CMS2A (DOK7-, MUSK-, GFPT1-, GMPPB-, TOR1AIP-mutated) when exhibiting predominant accessory nerve RNS decrements, CMS2B (CHRNE, CHRND, RAPSN) with predominant radial nerve RNS decrements, or CMS2C (AGRN) if there were predominant fibular decrements. Our algorithm may have a major impact on diagnostic and therapeutic monitoring in CMS patients, as well as for validation of the pathogenicity of genetic variants. It should also be part of the evaluation of unexplained muscle weakness or complex neuromuscular phenotypes. Show less

To present phenotype features of a large cohort of congenital myasthenic syndromes (CMS) and correlate them with their molecular diagnosis. Suspected CMS patients were divided into three groups: group A (limb, bulbar or axial weakness, with or without ocular impairment, and all the following: clinical fatigability, electrophysiology compatible with neuromuscular junction involvement and anticholinesterase agents response), group B (limb, bulbar or axial weakness, with or without ocular impairment, and at least one of additional characteristics noted in group A) and group C (pure ocular syndrome). Individual clinical findings and the clinical groups were compared between the group with a confirmed molecular diagnosis of CMS and the group without molecular diagnosis or with a non-CMS molecular diagnosis. Seventy-nine patients (68 families) were included in the cohort: 48 in group A, 23 in group B and 8 in group C. Fifty-one were considered confirmed CMS (30 CHRNE, 5 RAPSN, 4 COL13A1, 3 DOK7, 3 COLQ, 2 GFPT1, 1 CHAT, 1 SCN4A, 1 GMPPB, 1 CHRNA1), 7 probable CMS, 5 non-CMS and 16 unsolved. The chance of a confirmed molecular diagnosis of CMS was significantly higher for group A and lower for group C. Some individual clinical features, alterations on biopsy and electrophysiology enhanced specificity for CMS. Muscle imaging showed at least mild alterations in the majority of confirmed cases, with preferential involvement of soleus, especially in CHRNE CMS. Stricter clinical criteria increase the chance of confirming a CMS diagnosis, but may lose sensitivity, especially for some specific genes. Show less

Congenital myasthenic syndrome (CMS) is a clinically and genetically heterogeneous neuromuscular disorder characterized by muscle weakness and caused by mutations in more than 35 different genes. This condition should not be overlooked as a subset of patients with CMS are treatable. However, the diagnosis of CMS is often difficult due to the broad variability in disease severity and course. A five-year-old boy without remarkable family history was born with marked general muscle hypotonia and weakness, respiratory insufficiency, anomalies, and multiple joint contractures. Congenital myopathy was suspected based upon type 1 fiber predominance on muscle biopsy. However, he was diagnosed with CMS at age 4 years when his ptosis and ophthalmoplegia were found to be improved by edrophonium chloride and repetitive nerve stimulation showed attenuation of compound muscle action potentials. An exome sequencing identified a compound heterozygous missense variant of c.737C > T (p.A246V) and a novel intronic insertion c.1166 + 4₁₁₆₆ + 5insAAGCCCACCAC in RAPSN. RT-PCR analysis which showed the skipping of exon 7 in a skeletal muscle sample confirmed that the intronic insertion was pathogenic. His myasthenic symptoms were remarkably improved by pyridostigmine. The patient's diagnosis of CMS was confirmed by exome sequencing, and RT-PCR revealed that the skipping of exon 7 in RAPSN was caused by a novel intronic insertion. The genetic information uncovered in this case should therefore be added to the collection of tools for diagnosing and treating CMS. Show less

Clinical and molecular data on the occurrence and frequency of inherited neuromuscular disorders (NMD) in the Lebanese population is scarce. This study aims to provide a retrospective overview of hereditary NMDs based on our clinical consultations in Lebanon. Clinical and molecular data of patients referred to a multi-disciplinary consultation for neuromuscular disorders over a 20-year period (1999-2019) was reviewed. A total of 506 patients were diagnosed with 62 different disorders encompassing 10 classes of NMDs. 103 variants in 49 genes were identified. In this cohort, 81.4% of patients were diagnosed with motor neuron diseases and muscular dystrophies, with almost half of these described with spinal muscular atrophy (SMA) (40.3% of patients). We estimate a high SMA incidence of 1 in 7,500 births in Lebanon. Duchenne and Becker muscular dystrophy were the second most frequently diagnosed NMDs (17% of patients). These disorders were associated with the highest number of variants (39) identified in this study. A highly heterogeneous presentation of Limb Girdle Muscular Dystrophy and Charcot-Marie-Tooth disease was notably identified. The least common disorders (5.5% of patients) involved congenital, metabolic, and mitochondrial myopathies, congenital myasthenic syndromes, and myotonic dystrophies. A review of the literature for selected NMDs in Lebanon is provided. Our study indicates a high prevalence and underreporting of heterogeneous forms of NMDs in Lebanon- a major challenge with many novel NMD treatments in the pipeline. This report calls for a regional NMD patient registry. Show less

Congenital myasthenic syndromes (CMS) have some phenotypic overlap with seronegative myasthenia gravis (SNMG). The aim of this single center study was to assess the minimum occurrence of CMS misdiagnosed as double SNMG in a Brazilian cohort. The genetic analysis of the most common mutations in CHRNE, RAPSN, and DOK7 genes was used as the main screening tool. We performed genetic analysis in 22 patients with a previous diagnosis of 'double' SNMG. In this study, one CMS patient was confirmed due to the presence of compound heterozygous variants in the CHRNE gene (c.130insG/p.Cys210Phe). This study confirmed that CMS due to CHNRE mutations can be mistaken for SNMG. In addition, our study estimated the prevalence of misdiagnosed CMS to be 4.5% in 'double' SNMG patients of our center. Based on our findings, genetic screening could be helpful in the diagnostic workup of patients with 'double' SNMG in whom differential diagnosis is recommended. Show less

Altered ubiquitin signaling and disrupted protein quality control have been implicated in the pathogenesis of PD. The aim of the study was to systematically examine the overlaps between E3 ubiquitin ligase genes and early onset PD (EOPD). A total of 695 EOPD patients were analyzed aggregate burden for rare variants (MAF <0.001 and MAF <0.0001) in a total of 44 E3 ubiquitin ligase genes causing disorders involved in the nervous system. There was significant enrichment of the rare and rare damaging variants in the E3 ubiquitin ligase genes in EOPD patients. Detailly, in the gene-based level, the strongest associations were found in HERC1, IRF2BPL, KMT2D, RAPSN, RLIM, RNF168 and RNF216. Our findings highlighted the importance of UPS mechanism in the pathogenesis of PD from the genetic perspective. Moreover, our study also expanded the susceptible gene spectrum for PD. Show less

Mutations in RAPSN are an important cause of congenital myasthenic syndrome (CMS). In this study, we generated an induced pluripotent stem cell line (iPSC) derived from a 14-day-old male CMS patient carrying compound heterozygote mutations (c.532-2A > G and c.264C > A/p.Asn88Lys) in RAPSN gene. The established iPSC line harboring the original mutations, possessing a normal karyotype, is able to differentiate into all three germ layers in vitro and expresses pluripotency markers. Show less