Short-term changes in serum miRNA levels and patient-reported clinical outcomes in myasthenia gravis.

INTRODUCTION/AIMS: The circulating microRNAs (miRNAs) miR-150-5p, miR-30e-5p, and miR-21-5p have been suggested as potential biomarkers for myasthenia gravis (MG); however, the relationships between short-term natural changes of the miRNAs and patient-reported MG outcome scores have not been well-studied. We assessed the short-term fluctuations in miRNA levels and patient-reported outcome measures in MG. METHODS: This prospective cohort study included 39 MG patients with regular follow-ups and unchanged medications at the Neurology outpatient clinic at Uppsala University Hospital. Patients had weekly follow-up visits for 1 month, at which blood samples were drawn, and scores from MG activities of daily living (MG-ADL), MG quality-of-life-15 (MG-QoL15), and Fatigue Severity Scale (FSS) were assessed. Serum levels of miRNA miR-150-5p, miR-30e-5p, and miR-21-5p were analyzed using quantitative real-time PCR. RESULTS: Intra-individual levels of miR-30e-5p and miR-150-5p were stable, whereas a significant reduction in miR-21-5p was observed from week 1 to week 2 (p = .0024) and from week 2 to week 3 (p < .0001). There were intra-individual differences over a short time in MG-ADL, with higher scores in female patients (p = .0281) and a significant reduction from the first to the second weeks (p = .0281), whereas MG-QoL15 and FSS scores were stable. DISCUSSION: The suggested MG biomarkers miR-30e-5p and miR-150-5p were more stable than miR-21-5p over a short time, indicating their short-term stability as biomarkers. Prospective multi-center studies with longer periods of follow-up and matched controls are needed to validate these miRNAs as biomarkers in MG.

Thymic gene expression analysis reveals a potential link between HIF-1A and Th17/Treg imbalance in thymoma associated myasthenia gravis.

Myasthenia gravis (MG) is an immune-mediated disease frequently associated with thymic changes. Increased T helper 17 (Th17) cell activity and dysfunctional regulatory T (Treg) cells have been demonstrated in subgroups of MG. On the other hand, hypoxia-inducible factor 1 (HIF-1) has been shown to regulate the Th17/Treg balance by inducing Th17 differentiation while attenuating Treg development. To identify the underlying mechanisms of different thymic pathologies in MG development, we evaluated thymic samples from thymoma-associated myasthenia gravis (TAMG), MG with hyperplasia (TFH-MG) and thymoma without MG (TOMA) patients. Differential gene expression analysis revealed that TAMG and TFH-MG cells are associated with different functional pathways. A higher RORC/FOXP3 ratio provided evidence for Th17/Treg imbalance in TAMG potentially related to increased HIF1A. The hypoxic microenvironment in thymoma may be a driver of TAMG by increasing HIF1A. These findings may lead to new therapeutic approaches targeting HIF1A in the development of TAMG.

Construction of ceRNA network mediated by circRNAs screening from microarray and identification of novel biomarkers for myasthenia gravis.

BACKGROUND: Recent studies have revealed that circRNA can serve as ceRNA to participate in multiple autoimmune diseases. Our study aims to explore the key circRNA as ceRNA and biomarker for MG. METHODS: We used circRNA microarray to explore differentially expressed circRNAs (DECs) from MG and compare with control. Then, we predicted the target miRNA associated with DECs and screened miRNAs by the algorithm of random walk with restart (RWR). Next, we constructed the circRNA-miRNA-mRNA ceRNA regulated network (CMMC) to identify the hub objects. Following, we detected the expression of hub-circRNAs by RT-PCR. We verify has_circ_0004183 (circFRMD4) sponging miR-145-5p regulate cells proliferation using luciferase assay and CCK-8. RESULTS: We found that the expression level of circFRMD4 and has_circ_0035381 (circPIGB) were upregulated and has_circ_0089153(circ NUP214) had the lowest expression level in MG. Finally, we proved circFRMD4 sponging miR-145-5p regulate Jurkat cells proliferation. CircFRMD4 take part in the genesis and development of MG via circFRMD4/miR145-5p axis. CONCLUSIONS: We found that circFRMD4, circPIGB and circNUP214 can be considered as valuable potential novel biomarkers for AchR + MG. CircFRMD4 participate in the development of AchR + MG via targeting binding with miR-145-5p.

Mendelian randomization and colocalization analysis reveal novel drug targets for myasthenia gravis.

OBJECTIVE: Myasthenia gravis (MG) is a complex autoimmune disease affecting the neuromuscular junction with limited drug options, but the field of MG treatment recently benefits from novel biological agents. We performed a drug-targeted Mendelian randomization (MR) study to identify novel therapeutic targets of MG. METHODS: Cis-expression quantitative loci (cis-eQTL), which proxy expression levels for 2176 druggable genes, were used for MR analysis. Causal relationships between genes and disease, identified by eQTL MR analysis, were verified by comprehensive sensitivity, colocalization, and protein quantitative loci (pQTL) MR analyses. The protein-protein interaction (PPI) analysis was also performed to extend targets, followed by enzyme-linked immunosorbent assay (ELISA) to explore the serum level of drug targets in MG patients. A phenome-wide MR analysis was then performed to assess side effects with a clinical trial review assessing druggability. RESULTS: The eQTL MR analysis has identified eight potential targets for MG, one for early-onset MG and seven for late-onset MG. Further colocalization analyses indicated that CD226, CDC42BPB, PRSS36, and TNFSF12 possess evidence for colocalization with MG or late-onset MG. pQTL MR analyses identified the causal relations of TNFSF12 and CD226 with MG and late-onset MG. Furthermore, PPI analysis has revealed the protein interaction between TNFSF12-TNFSF13(APRIL) and TNFSF12-TNFSF13B(BLyS). Elevated TNFSF13 serum level of MG patients was also identified by ELISA experiments. This study has ultimately proposed three promising therapeutic targets (TNFSF12, TNFSF13, TNFSF13B) of MG. CONCLUSIONS: Three drug targets associated with the BLyS/APRIL pathway have been identified. Multiple biological agents, including telitacicept and belimumab, are promising for MG therapy.

Small extracellular vesicle microRNAs in pediatric myasthenia gravis plasma and skeletal muscle.

BACKGROUND: The diagnosis of myasthenia gravis (MG) in children remains difficult. Circulating small extracellular vesicle (sEV)-derived miRNAs (sEV-miRNAs) have been recognized as biomarkers of various diseases and can be excreted by different cell types. These biomarker candidates also play a vital role in autoimmune diseases via intercellular communication. METHODS: In the present study, we used sEV isolation and purification methods to extract the plasma-derived sEV-miRNAs from children with MG and healthy controls. A small RNA sequencing analysis confirmed the miRNA expression features in plasma-derived sEVs from MG patients. The miRNA expression analysis in vitro was determined using microarray analysis. The enrichment and network analyses of altered sEV-miRNAs were performed using miRNA databases and Database for Annotation, Visualization, and Integrated Discovery website. Quantitative real-time polymerase chain reaction was performed for validation of sEV-miRNA. The diagnostic power of altered sEV-miRNAs was evaluated using receiver operating characteristic curve analyses. RESULTS: Twenty-four sEV-miRNAs with altered expression level were identified between groups by DESeq2 method. The miRNAs were extracted from the sEVs, which were isolated from human primary skeletal muscle cell culture treated with mAb198. The target genes and enriched pathways of sEV-miRNAs partially overlapped between cell supernatant and plasma samples. The significantly downregulated miR-143-3p was validated in quantitative real-time polymerase chain reaction analysis. CONCLUSIONS: For the first time, we report that plasma-derived sEV-miRNAs may act as novel circulating biomarkers and therapeutic targets in pediatric MG.

Integrative multi-omics analysis identifies genetically supported druggable targets and immune cell specificity for myasthenia gravis.

BACKGROUND: Myasthenia gravis (MG) is a chronic autoimmune disorder characterized by fluctuating muscle weakness. Despite the availability of established therapies, the management of MG symptoms remains suboptimal, partially attributed to lack of efficacy or intolerable side-effects. Therefore, new effective drugs are warranted for treatment of MG. METHODS: By employing an analytical framework that combines Mendelian randomization (MR) and colocalization analysis, we estimate the causal effects of blood druggable expression quantitative trait loci (eQTLs) and protein quantitative trait loci (pQTLs) on the susceptibility of MG. We subsequently investigated whether potential genetic effects exhibit cell-type specificity by utilizing genetic colocalization analysis to assess the interplay between immune-cell-specific eQTLs and MG risk. RESULTS: We identified significant MR results for four genes (CDC42BPB, CD226, PRSS36, and TNFSF12) using cis-eQTL genetic instruments and three proteins (CTSH, PRSS8, and CPN2) using cis-pQTL genetic instruments. Six of these loci demonstrated evidence of colocalization with MG susceptibility (posterior probability > 0.80). We next undertook genetic colocalization to investigate cell-type-specific effects at these loci. Notably, we identified robust evidence of colocalization, with a posterior probability of 0.854, linking CTSH expression in TH2 cells and MG risk. CONCLUSIONS: This study provides crucial insights into the genetic and molecular factors associated with MG susceptibility, singling out CTSH as a potential candidate for in-depth investigation and clinical consideration. It additionally sheds light on the immune-cell regulatory mechanisms related to the disease. However, further research is imperative to validate these targets and evaluate their feasibility for drug development.

The investigation of killer-cell immunoglobulin-like receptors (KIRs) and their HLA ligands in Iranian patients with myasthenia gravis.

BACKGROUND: Myasthenia gravis (MG) is a disabling disease with the underlying pathophysiology of auto-antibodies attacking the postsynaptic acetylcholine receptors of neuromuscular junctions causing muscle weakness. Natural killer (NK) cells are innate immune cells that play an important regulative role in immune responses. The human killer-cell immunoglobulin-like receptors (KIRs) family is one of the receptors on NK cells that can either activate or inhibit NK cells. This study aimed to assess the possible role of KIR and their human leukocyte antigen (HLA) ligand genes susceptibility to MG in Iranian patients. METHOD: One hundred and sixty-three patients with MG diagnosis based on the presence of clinical symptoms and laboratory tests and 400 healthy volunteers were studied. We used the polymerase chain reaction (PCR) technique for genotyping 15 KIRs and 5 HLA genes. RESULTS: The results demonstrated that there was no significant difference in the frequency of KIR genes and inhibitory KIR genotypes between controls and patients. In MG patients, HLA-C1Asn80 was significantly less frequent than in matched controls. The frequency of HLA genotype number 7 was significantly lower in MG cases, compared to the controls. Analysis of activating KIR genotypes showed that genotype number 10 was significantly less frequent in MG cases than in matched controls. CONCLUSION: Our results suggest that the presence HLA-C1Asn80 might play a protective role against the pathogenesis of MG. The significantly decreased prevalence of one activating KIR genotype and one of the HLA genotypes in MG cases suggest that these genotypes can reduce the risk of MG development. To specifically reveal the impact of KIR and HLA in MG, more studies are required.

Autoimmune thyroid disease and myasthenia gravis: a study bidirectional Mendelian randomization.

Background: Previous studies have suggested a potential association between AITD and MG, but the evidence is limited and controversial, and the exact causal relationship remains uncertain. Objective: Therefore, we employed a Mendelian randomization (MR) analysis to investigate the causal relationship between AITD and MG. Methods: To explore the interplay between AITD and MG, We conducted MR studies utilizing GWAS-based summary statistics in the European ancestry. Several techniques were used to ensure the stability of the causal effect, such as random-effect inverse variance weighted, weighted median, MR-Egger regression, and MR-PRESSO. Heterogeneity was evaluated by calculating Cochran's Q value. Moreover, the presence of horizontal pleiotropy was investigated through MR-Egger regression and MR-PRESSO. Results: The IVW method indicates a causal relationship between both GD(OR 1.31,95%CI 1.08 to 1.60,P=0.005) and autoimmune hypothyroidism (OR: 1.26, 95% CI: 1.08 to 1.47, P =0.002) with MG. However, there is no association found between FT4(OR 0.88,95%CI 0.65 to 1.18,P=0.406), TPOAb(OR: 1.34, 95% CI: 0.86 to 2.07, P =0.186), TSH(OR: 0.97, 95% CI: 0.77 to 1.23, P =0.846), and MG. The reverse MR analysis reveals a causal relationship between MG and GD(OR: 1.50, 95% CI: 1.14 to 1.98, P =3.57e-3), with stable results. On the other hand, there is a significant association with autoimmune hypothyroidism(OR: 1.29, 95% CI: 1.04 to 1.59, P =0.019), but it is considered unstable due to the influence of horizontal pleiotropy (MR PRESSO Distortion Test P < 0.001). MG has a higher prevalence of TPOAb(OR: 1.84, 95% CI: 1.39 to 2.42, P =1.47e-5) positivity and may be linked to elevated TSH levels(Beta:0.08,95% CI:0.01 to 0.14,P =0.011), while there is no correlation between MG and FT4(Beta:-9.03e-3,95% CI:-0.07 to 0.05,P =0.796). Conclusion: AITD patients are more susceptible to developing MG, and MG patients also have a higher incidence of GD.

Mendelian randomization analyses of known and suspected risk factors and biomarkers for myasthenia gravis overall and by subtypes.

BACKGROUND: Myasthenia gravis (MG) is an autoimmune disease that affects neuromuscular junction. The literature suggests the involvement of circulating cytokines (CK), gut microbiota (GM), and serum metabolites (SM) with MG. However, this research is limited to observational trials, and comprehensive causal relationship studies have not been conducted. Based on published datasets, this investigation employed Mendelian Randomization (MR) to analyze the known and suspected risk factors and biomarkers causal association of MG and its subtypes. METHODS: This research used two-sample MR and linkage disequilibrium score (LDSC) regression of multiple datasets to aggregate datasets acquired from the genome-wide association studies (GWAS) to assess the association of MG with 41-CK, 221-GM, and 486-SM. For sensitivity analysis and to validate the robustness of the acquired data, six methods were utilized, including MR-Egger regression, inverse variance weighting (IVW), weighted median, and MR-PRESSO. RESULTS: The MR method identified 20 factors significantly associated with MG, including 2 CKs, 6 GMs, and 9 SMs. Further analysis of the factors related to the two MG subtypes, early-onset MG (EOMG) and late-onset MG (LOMG), showed that EOMG had a high overlap with MG in the intestinal flora, while LOMG had a greater similarity in CKs and SMs. Furthermore, LDSC regression analysis indicated that Peptococcaceae, oxidized biliverdin, and Kynurenine had significant genetic correlations with general MG, whereas EOMG was highly correlated with Intestinibacter, while LOMG had significant genetic associations with Kynurenine and Glucose. CONCLUSION: This research furnishes evidence for the potential causal associations of various risk factors with MG and indicates a heterogeneous relationship between CKs, GMs, and SMs with MG subtypes.

Mendelian randomization study revealed a gut microbiota-neuromuscular junction axis in myasthenia gravis.

A growing number of studies have implicated that gut microbiota abundance is associated with myasthenia gravis (MG). However, the causal relationship underlying the associations is still unclear. Here, we aim to investigate the causal effect of gut microbiota on MG using Mendelian randomization (MR) method. Publicly available Genome-wide association study (GWAS) summary-level data for gut microbiota and for MG were extracted. Inverse variance weighted was used as the main method to analyze causality. The robustness of the results was validated with sensitivity analyses. Our results indicated that genetically predicted increased phylum Lentisphaerae (OR = 1.319, p = 0.026), class Lentisphaerae (OR = 1.306, p = 0.044), order Victivallales (OR = 1.306, p = 0.044), order Mollicutes (OR = 1.424, p = 0.041), and genus Faecalibacterium (OR = 1.763, p = 0.002) were potentially associated with a higher risk of MG; while phylum Actinobacteria (OR = 0.602, p = 0.0124), class Gammaproteobacteria (OR = 0.587, p = 0.036), family Defluviitaleaceae (OR = 0.695, p = 0.047), family Peptococcaceae (OR = 0.698, p = 0.029), and family Family XIII (OR = 0.614, p = 0.017) were related to a lower risk of MG. The present study provides genetic evidence for the causal associations between gut microbiota and MG, thus suggesting novel insights into the gut microbiota-neuromuscular junction axis in the pathogenesis of MG.

Myasthenia gravis and five autoimmune diseases: a bidirectional Mendelian randomization study.

BACKGROUND: The association between myasthenia gravis (MG) and other autoimmune diseases is well established. In this study, we aimed to investigate the causal effects between MG and five other autoimmune diseases, including autoimmune thyroid disease (AITD), multiple sclerosis (MS), rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), and type 1 diabetes (T1DM). METHODS: We conducted a bidirectional Mendelian randomization (MR) study by using seven published genome-wide association studies (GWAS), including MG (1873 patients versus 36,370 controls), AITD (autoimmune hypothyroidism) (22,997 patients versus 175,475 controls), AITD (autoimmune hyperthyroidism) (962 patients versus 172,976 controls), MS (47,429 patients versus 68,374 controls), RA (14,361 patients versus 43,923 controls), SLE (4222 patients versus 8431 controls), and T1DM (9266 patients versus 15,574 controls). We used the inverse-variance-weighted (IVW) method, weighted-median (WM) estimator, MR-Egger regression, and MR PRESSO in our analyses. We also carried out detailed sensitivity analyses for each direction using the aforementioned methods. RESULTS: When MG was treated as the exposure, MR evidence suggested a causal relationship between MG and T1DM, SLE, AITD (both hypothyroidism and hyperthyroidism), and MS (excluding RA). Using the IVW method, we found that MG was associated with increased risk of T1DM (OR = 1.94; 95% CI, 1.16-3.26; p = 0.012), SLE (OR = 1.47; 95% CI, 1.02-2.13; p = 0.04), AITD (hypothyroidism) (OR = 1.31; 95% CI, 1.02-1.68; p = 0.039), AITD (hyperthyroidism) (OR = 1.55; 95% CI, 1.15-2.09; p = 0.004), and MS (OR = 1.46; 95% CI, 1.01-2.09; p = 0.041). When MG was treated as the outcome, MR evidence suggested that RA, T1DM, and SLE were causal factors in MG. Using the IVW method, we found that the risk of MG increased with exposure to RA (OR = 1.21; 95% CI, 1.08-1.37; p = 0.002), T1DM (OR = 1.09; 95% CI, 1.02-1.16; p = 0.006), and SLE (OR = 1.12; 95% CI, 1.02-1.23; p = 0.018). CONCLUSIONS: This study demonstrated a causal relationship between MG and several other autoimmune diseases. Our results supported a bidirectional causal association between MG and SLE/T1DM. Our findings also provided reliable evidence that MG is associated with increased risk of AITD. Meanwhile, we also showed that RA is a possible causal driver of MG risk.

Study of serum exosome miRNA as a biomarker for early onset adult ouclar myastthenia gravis.

BACKGROUND: By extracting and sequencing miRNAs from serum exosomes of patients with early-onset ocular myasthenia gravis (OMG), generalized myasthenia gravis (GMG) and healthy controls, we screened differentially expressed miRNAs and explored the possibility as potential biomarkers for early-onset OMG. METHODS: Peripheral blood samples were collected from patients with early-onset OMG, early-onset GMG, and age-matched healthy subjects, with 6 samples in each group. All these patients were diagnosed as MG for the first time and did not undergo any treatment. Exosomes miRNAs were extracted from the serum and performed deep sequencing; the differentially expressed miRNAs were compared and analyzed between OMG, GMG, and healthy control groups using edgeR. The differential expression standard was set to | log2FC |>1, p < 0.05. Target prediction of mRNAs were performed using miRTarBase, TargetScan, and miRDB databases, and a protein-protein interaction (PPI) network was constructed subsequently. The miRNAs with a significant difference were validated using RT-qPCR (10 early-onset OMG patients, 10 early-onset GMG patients and 10 age-sex-matched healthy subjects), and the value of the area under the ROC curve (AUC) was used to assess the diagnostic accuracy and evaluate clinical prognostic value. RESULTS: In total, one upregulated (miR-130a-3p) miRNA was obtained through the upregulated intersection between control vs OMG and OMG vs GMG; four downregulated (miR-4712-3p; miR-6752-5p; miR-320d; miR-3614-3p) miRNAs were obtained through the downregulated intersection between control vs OMG and OMG vs GMG. A total of 408 target genes were predicted for the five differentially expressed miRNAs. The mTOR signaling pathway and Rap1 signaling pathway were significantly enriched based on the enrichment results. RT-qPCR findings revealed that for the OMG, the expression of miR-320d, miR-4712-3p and miR-3614-3p was markedly up-/down-regulated as compared to GMG and healthy control group. The AUC for the three miRNAs between OMG and healthy control groups were 0.78, 0.79 and 0.79 respectively; the AUC between OMG and GMG was 0.84. CONCLUSIONS: The present study identified three novel miRNAs as candidate biomarkers for early-onset OMG patients and it was expected to provide a possibility and a new orientation for serum exosomal miRNAs as OMG diagnostic biomarkers.

Bidirectional association between hypothyroidism and myasthenia gravis: a Mendelian randomized study.

OBJECTIVES: Although observational studies have suggested a link between hypothyroidism and myasthenia gravis (MG), a causal relationship has not been established. We aimed to investigate the causal association using a two-sample Mendelian randomization (MR) study. METHODS: Using summary statistics from genome-wide association studies involving 494,577 and 38,243 individuals, single-nucleotide polymorphisms exhibiting no linkage disequilibrium (r2 ≤ 0.001) and displaying significant differences (p ≤ 5 × 10-8) were selected for hypothyroidism and MG. To assess the potential causality relationship between hypothyroidism and MG, MR analysis was conducted using inverse variance weighted (IVW), weighted median method, and MR-Egger. The MR-Egger regression, heterogeneity test, pleiotropy test, and leave-one-out sensitivity test were employed to examine sensitivity analyses. In addition, validation datasets were used to validate the relevant results. RESULTS: Genetic liability to hypothyroidism was positively associated with MG (IVW, OR: 1.36, 95% CI: 1.17-1.58, p = 7.53 × 10-05; weighted median, OR: 1.19, 95% CI: 0.70-2.02, p = 0.522; MR-Egger, OR: 1.19, 95% CI: 0.98-1.45, p = 0.080). Among the three MR methods, the correlation between hypothyroidism and MG genetic prediction was consistent. The independent validation set (IVW, OR: 466.47, 95% CI: 4.70 -46,285.95, p = 0.01) further supported this. Additionally, bidirectional studies showed that using IVW, there was no reverse causality (OR: 1.104, 95%CI: 0.96-1.27, p = 0.170). DISCUSSION: This MR study showed that hypothyroidism can increase the risk of MG. Further investigation into the underlying mechanisms of this potential causality is warranted to offer novel therapeutic options for MG in the future.

Rs1800629 polymorphism in TNF-alpha is associated with the susceptibility and initial short-term glucocorticoids efficacy in myasthenia gravis patients.

Tumor necrosis factor-alpha (TNF-α) is a potent pro-inflammatory agent involved in various autoimmune and inflammatory diseases including myasthenia gravis (MG). In this study, we enrolled 409 adult MG patients and 487 healthy individuals to investigate the association between TNF-α polymorphism and MG. We found the rs1800629 A allele frequency was significantly higher in the MG group than in the control group. Subgroup analysis revealed that the A allele frequencies were significantly higher in the early-onset subgroup, non-thymoma subgroup, ocular-onset subgroup, and mild severity subgroup than in the control group. To minimize the interactions between clinical features, we used a comprehensive classification and found that the rs1800629 A allele frequency was significantly higher in the non-thymoma AChR-Ab negative subgroup than in the control group. In the analysis of initial short-term glucocorticoids (GC) efficacy in the treatment-naive patients, the rs1800629 A allele frequency was significantly higher in the unresponsive subgroup than in the responsive group and the control group. Logistic regression demonstrated the rs1800629 genotypes in the dominant model and disease duration prior to GC treatment independently contributed to initial short-term GC efficacy. In conclusion, our study revealed that in Chinese adult MG patients, rs1800629 polymorphism in TNF-α was associated with the susceptibility of MG and might indicate the initial short-term GC efficacy.

Genetic, serological and clinical evaluation of childhood myasthenia syndromes- single center subgroup analysis experience in Turkey.

BACKGROUND: Congenital myasthenic syndrome is a disease that occurs due to several types such as mutations in different pre-synaptic, synaptic, post-synaptic proteins and, glycosylation defects associated with congenital myopathy. Juvenile myasthenia gravis is an autoimmune condition usually caused by antibodies targeting the acetylcholine receptor. AIMS: Our objective is to conduct an analysis on the subgroup traits exhibited by patients who have been diagnosed with congenital myasthenic syndrome and juvenile myasthenia gravis, with a focus on their long-term monitoring and management. METHODS: This study was conducted on children diagnosed with myasthenia gravis, who were under the care of Dokuz Eylul University's Department of Pediatric Neurology for a period of ten years. RESULTS: A total of 22 (12 congenital myasthenic syndrome, 10 juvenile myasthenia gravis) patients were identified. Defects in the acetylcholine receptor (6/12) were the most common type in the congenital myasthenic syndrome group. Basal-lamina-related defects (5/12) were the second most prevalent. One patient had a GFPT1 gene mutation (1/12). Patients with ocular myasthenia gravis (n = 6) exhibited milder symptoms. In the generalized myasthenia gravis group (n = 4), specifically in postpubertal girls, a more severe clinical progression was observed, leading to the implementation of more aggressive treatment strategies. CONCLUSION: This study highlights that clinical recognition of congenital myasthenic syndrome and knowledge of related genes will aid the rapid diagnosis and treatment of these rare neuromuscular disorders. Findings in the juvenile myasthenia gravis group demonstrate the impact of pubertal development and the need for timely and appropriate active therapy, including thymectomy, to improve prognosis.

Association between COVID-19 and myasthenia gravis (MG): A genetic correlation and Mendelian randomization study.

BACKGROUND: Observational studies have suggested an association between coronavirus disease 2019 (COVID-19) and myasthenia gravis (MG). Here, we aimed to estimate the genetic correlation and causal relationship between COVID-19 susceptibility, hospitalization, severity, and MG phenotypes using linkage disequilibrium score regression (LDSC) and Mendelian randomization (MR) approach. METHODS: Summary statistics of COVID-19 susceptibility, hospitalization, and severity were used as instrumental variables for exposure traits. Large-scale genome-wide association study (GWAS) data for MG were used as outcome traits. The inverse variance weighted approach was used for the main MR analysis, complemented by MR-Egger, weighted median, simple mode, and weighted mode methods. Sensitivity analysis was implemented using Cochran's Q test, MR-PRESSO method, and MR-Egger intercept test. RESULTS: LDSC analysis did not reveal any genetic correlation among COVID-19 susceptibility, hospitalization, severity, and MG phenotypes, including MG, early-onset MG, and late-onset MG (p > .05). Our MR analysis did not provide evidence supporting a causal effect of COVID-19 susceptibility, hospitalization, or severity on MG phenotypes (p > .05). Extensive sensitivity analysis strengthened the robustness and consistency of the MR estimates. CONCLUSION: Our study did not find evidence of a genetic correlation or causal relationship among COVID-19 susceptibility, hospitalization, severity, and MG. Future studies with more GWAS data are needed to evaluate the association between COVID-19 phenotypes and MG and its subgroups.

Peripheral immune landscape for hypercytokinemia in myasthenic crisis utilizing single-cell transcriptomics.

BACKGROUND: Myasthenia gravis (MG) is the most prevalent autoimmune disorder affecting the neuromuscular junction. A rapid deterioration in respiratory muscle can lead to a myasthenic crisis (MC), which represents a life-threatening condition with high mortality in MG. Multiple CD4+ T subsets and hypercytokinemia have been identified in the peripheral pro-inflammatory milieu during the crisis. However, the pathogenesis is complicated due to the many types of cells involved, leaving the underlying mechanism largely unexplored. METHODS: We conducted single-cell transcriptomic and immune repertoire sequencing on 33,577 peripheral blood mononuclear cells (PBMCs) from two acetylcholine receptor antibody-positive (AChR +) MG patients during MC and again three months post-MC. We followed the Scanpy workflow for quality control, dimension reduction, and clustering of the single-cell data. Subsequently, we annotated high-resolution cell types utilizing transfer-learning models derived from publicly available single-cell immune datasets. RNA velocity calculations from unspliced and spliced mRNAs were applied to infer cellular state progression. We analyzed cell communication and MG-relevant cytokines and chemokines to identify potential inflammation initiators. RESULTS: We identified a unique subset of monocytes, termed monocytes 3 (FCGR3B+ monocytes), which exhibited significant differential expression of pro-inflammatory signaling pathways during and after the crisis. In line with the activated innate immune state indicated by MC, a high neutrophil-lymphocyte ratio (NLR) was confirmed in an additional 22 AChR + MC patients in subsequent hemogram analysis and was associated with MG-relevant clinical scores. Furthermore, oligoclonal expansions were identified in age-associated B cells exhibiting high autoimmune activity, and in CD4+ and CD8+ T cells demonstrating persistent T exhaustion. CONCLUSIONS: In summary, our integrated analysis of single-cell transcriptomics and TCR/BCR sequencing has underscored the role of innate immune activation which is associated with hypercytokinemia in MC. The identification of a specific monocyte cluster that dominates the peripheral immune profile may provide some hints into the etiology and pathology of MC. However, future functional studies are required to explore causality.

Genetically predicted effects of physical activity and sedentary behavior on myasthenia gravis: evidence from mendelian randomization study.

BACKGROUND: Myasthenia gravis (MG) is an autoimmune disorder affecting the neuromuscular junction. Despite the potential benefits of higher physical activity and lower sedentary behavior in MG patients, evidence from observational studies for the effect of physical activity on the risk of MG is limited and inconclusive. METHODS: We employed linkage disequilibrium score (LDSC) regression, two-sample Mendelian randomization (MR), and its multivariable extension analyses (MVMR) to assess the relationship between leisure screen time (LST), moderate-to-vigorous intensity physical activity during leisure time (MVPA) and the risk of MG using genome-wide association studies (GWAS) summary datasets. MR analyses were performed using the inverse-variance-weighted (IVW), weighted-median, and MR-Egger regression. Sensitivity analyses were further performed using alternative instruments to test the robustness of our findings. RESULTS: We found evidence of genetic overlap between LST (rg = 0.113, P = 0.023) and MG, as well as between MVPA (rg=-0.220, P = 0.0001) and MG, using LDSC method. The results of the MR suggested an association between genetic liability to LST and increased risk of MG (IVW OR = 1.609, 95% CI = 1.153 to 2.244; P = 0.005). This association was particularly notable for late-onset MG (IVW OR = 1.698, 95% CI = 1.145 to 2.518; P = 0.008), but not for early-onset MG. Consistent findings were obtained in the MVMR analysis using BMI as covariate (IVW OR = 1.593, 95% CI 1.167 to 2.173, P = 0.003). However, the MR analysis does not support a substantial causal effect of MVPA on the risk of MG. CONCLUSION: Our findings support a causal effect of sedentary behavior as measured by LST on MG, indicating that lack of exercise may play a role in the development of MG. Longitudinal and interventional studies of this association are warranted.

Myasthenia gravis and congenital myasthenic syndromes.

Myasthenia gravis is an autoimmune disorder caused by antibodies against elements in the postsynaptic membrane at the neuromuscular junction, which leads to muscle weakness. Congenital myasthenic syndromes are rare and caused by mutations affecting pre- or postsynaptic function at the neuromuscular synapse and resulting in muscle weakness. MG has a prevalence of 150-250 and an annual incidence of 8-10 individuals per million. The majority has disease onset after age 50 years. Juvenile MG with onset in early childhood is more common in East Asia. MG is subgrouped according to type of pathogenic autoantibodies, age of onset, thymus pathology, and generalization of muscle weakness. More than 80% have antibodies against the acetylcholine receptor. The remaining have antibodies against MuSK, LRP4, or postsynaptic membrane antigens not yet identified. A thymoma is present in 10% of MG patients, and more than one-third of thymoma patients develop MG as a paraneoplastic condition. Immunosuppressive drug therapy, thymectomy, and symptomatic drug therapy with acetylcholine esterase inhibitors represent cornerstones in the treatment. The prognosis is good, with the majority of patients having mild or moderate symptoms only. Most congenital myasthenic syndromes are due to dysfunction in the postsynaptic membrane. Symptom debut is in early life. Symptomatic drug treatment has sometimes a positive effect.

Cytokines Single Nucleotide Polymorphisms (SNPs) Association With Myasthenia Gravis (MG) In Algerian Patients: A Case-Control Study On A Small Group.

ABSTRACT: Myasthenia gravis (MG) is an autoimmune disease of multifactorial etiology in which genetic factors and cytokines seem to play an important role. The aim of this study was to investigate potential associations of cytokines single nucleotide polymorphisms (SNPs) and MG in Algerian patients. We performed a case-control study that included 27 patients and 74 healthy subjects. Cytokines SNPs genotyping was performed by the polymerase chain reaction sequence-specific primers (PCR-SSP) method. Our results showed that the TNF-α -308G/A (P < 0.005) and TGF-ß1 +869T/T (P < 0.05) genotypes were more frequent among patients with MG compared with healthy individuals, whereas TNF-α -308G/G (P < 0.0001), TGF-ß1 +869T/C (P < 0.05), and IFN-γ +874A/A (P < 0.05) were less frequent. Our results also showed that IL-10 and IL-6 SNPs did not show any significant difference in distribution between MG patients and healthy individuals. Our observations support the hypothesis that implicates genetic variants of certain cytokines in MG. However, ours results should be replicated with a larger sample size. In addition, the precise underlying processes remain to be clarified. HIGHLIGHTS: TNF-α -308G/A and TGF-ß1 +869T/C genotypes predispose to MG.IFN-γ +874A/A genotype protects against MG.IL-6 -174C/G SNP is not associated with MG.