Myasthenia gravis in South Africans: Racial differences in clinical manifestations

Lupus and other autoimmune diseases: Epidemiology in the population of African ancestry and diagnostic and management challenges in Africa

Autoimmune diseases are prevalent among people of African ancestry living outside Africa. However, the burden of autoimmune diseases in Africa is not well understood. This article provides a global overview of the current burden of autoimmune diseases in individuals of African descent. It also discusses the major factors contributing to autoimmune diseases in this population group, as well as the challenges involved in diagnosing and managing autoimmune diseases in Africa.

Possible sex and racial disparities in myasthenia gravis care

INTRODUCTION/AIMS

Given the importance of early diagnosis and treatment of myasthenia gravis (MG), it is critical to understand disparities in MG care. We aimed to determine if there are any differences in testing, treatment, and/or access to neurologists for patients of varying sex and race/ethnicity with MG.

METHODS

We used a nationally representative healthcare claims database of privately insured individuals (2001-2018) to identify incident cases of MG using a validated definition. Diagnostic testing, steroid-sparing agents, intravenous immunoglobulin (IVIG), plasma exchange (PLEX), and thymectomy were defined using drug names or CPT codes. Steroid use was defined using AHFS class codes. We also determined whether an individual had a visit to a neurologist and the time between primary care and neurologist visits. Logistic regression determined associations between sex and race/ethnicity and testing, treatments, and access to neurologists.

RESULTS

Female patients were less likely to get a computed tomography (CT) chest (odds ratio (OR) 0.73, 95% confidence interval (CI): 0.64-0.83), receive steroids (OR: 0.85, 95% CI: 0.75-0.97), steroid-sparing agents (OR: 0.84, 95% CI: 0.72-0.97), and IVIG or PLEX (OR: 0.80, 95% CI: 0.67-0.95). Black patients were less likely to receive steroids (OR: 0.78, 95% CI: 0.63-0.96). No significant disparities were seen in access to neurologists.

DISCUSSION

We found healthcare disparities in MG treatment with female and Black patients receiving less treatment than men and those of other races/ethnicities. Further research and detailed assessments accounting for individual patient factors are needed to confirm these apparent disparities.

Outcome and clinical features in juvenile myasthenia gravis: A systematic review and meta-analysis

Background

Juvenile myasthenia gravis (JMG) is a rare autoimmune disease that has so far only been described in small cohort studies. We defined the clinical characteristics, management, and outcomes of JMG patients over the past 22 years.

Methods

A search of PubMed, EMBASE, and web of science (1/2000–2/2022) identified all English language and human studies of JMG. The population was patients diagnosed with JMG. Outcomes included the history of myasthenic crisis, autoimmune comorbidity, mortality, and treatment outcome. Data extraction was performed by independent reviewers. And we performed a pooled reanalysis of all published data in the included studies and compared with other studies of adult cohorts.

Results

We identified 11 articles describing 1,109 patients diagnosed between 2006 and 2021. JMG occurred in 60.4% of female patients. The mean age at presentation was 7.38 years old, and 60.6% of the patients had ocular symptoms as the first clinical manifestation. The most common initial presentation was ptosis, which occurred in 77.7% patients. AchR-Ab positive accounted for 78.7%. 641 patients received thymus examination, found to have thymic hyperplasia in 64.9% and thymoma in 2.2%. Autoimmune comorbidity was found in 13.6% and the most common one is thyroid disease (61.5%). First-line therapy, including pyridostigmine and steroids, was initiated in 97.8 and 68.6%, respectively. Six patients resolved spontaneously without treatment. Thymectomy was performed in 45.6%. 10.6% of patients had a history of myasthenic crisis. Completely stable remission was achieved in 23.7% and mortality was reported in 2 studies, which reported 8 deaths.

Conclusion

JMG is a rare disease with a relatively benign course, and differs from adult MG in some clinical features. The treatment regimen guideline for children is still not well-established. There is a need for prospective studies to properly evaluate treatment regimes.

Analysis of length of stay and treatment emergent complications in hospitalized myasthenia gravis patients with exacerbation

INTRODUCTION

AIMS Myasthenia Gravis (MG) is an autoimmune neuromuscular disease in which patients suffer from recurrent exacerbation. There are insufficient data measuring the effects of the resources employed before and during acute exacerbation on subsequent disease outcomes. This study aims to identify factors which lead to lengthened hospital stay.

METHODS

This is a retrospective chart review of acute MG exacerbations requiring hospitalization. Exacerbations were identified using ICD-9/ICD-10 codes and considered the following variables: age and Myasthenia Gravis Foundation of America (MGFA) class at initial MG diagnosis, age and MGFA class at exacerbation, sex, thymectomy, cause of exacerbation, treatment regimen at time of exacerbation, inpatient treatment regimen, length of hospital stay (LOS), intubation, use of noninvasive ventilation, complications, and disposition.

RESULTS

Seventy patients with 141 hospitalizations were identified. Crisis management characterized by intubation and plasmapheresis positively correlated with LOS (both p < .001). Almost 1/5 hospitalizations required intubation. Previous thymectomy negatively correlated with LOS (p < .05). In contrast, male sex correlated with longer LOS (p < .05). One-third of hospital stays were followed by discharge to a post-acute care facility, 7% home with home health, and 1 hospitalization resulted in death.

DISCUSSION

Plasmapheresis, intubation, and male sex were associated with increased LOS in acute MG exacerbation. Intubation appears to be the strongest predictor of LOS. Those with previous thymectomy had shorter hospital stays. The role of thymectomy in the acute setting merits further analysis.

A single low-dose rituximab infusion in severe chronic refractory myasthenia gravis in resource-limited settings

The benefits of multi-dose rituximab cycles in patients with refractory anti-muscle-specific kinase antibody myasthenia gravis (MuSK+MG) are well reported, although less consistently in anti-acetylcholine receptor antibody MG (AChR+MG). Responsivity data to single low-dose rituximab infusions for refractory autoimmune myasthenia, are limited. Here, observational outcomes using MG grading scores and prednisone doses, before and after at least six months of a single-dose infusion of rituximab, were audited in previously treatment-refractory MG patients in a resource-limited setting. Seventeen moderately-severe to severely symptomatic MG patients received single low-dose rituximab infusions (median 500-600 mg) after a median MG duration of 6 years; 13 individuals responded including 5/5 MuSK+MG, 7/10 AChR+MG and 1/2 double seronegative MG. Three (60%) MuSK+MG and three (30%) AChR+MG achieved persistent asymptomatic status. Although more MuSK+MG vs AChR+MG cases stopped prednisone (80% vs 20%, respectively), the prednisone doses in the AChR+MG group was significantly reduced ≥30% (p = 0.008) due to improved MG composite scores (p = 0.016) and with durable benefit (median 12 months). There were no differences between responders and non-responders in MG duration and age at infusion. These results suggest that a single low-dose rituximab infusion is worth trying in refractory MG, including AChR+MG patients, as some patients showed good and durable responses. These results are particularly relevant to resource-limited settings.

Post-Infectious Autoimmunity in the Central (CNS) and Peripheral (PNS) Nervous Systems: An African Perspective

The direct impact and sequelae of infections in children and adults result in significant morbidity and mortality especially when they involve the central (CNS) or peripheral nervous system (PNS). The historical understanding of the pathophysiology has been mostly focused on the direct impact of the various pathogens through neural tissue invasion. However, with the better understanding of neuroimmunology, there is a rapidly growing realization of the contribution of the innate and adaptive host immune responses in the pathogenesis of many CNS and PNS diseases. The balance between the protective and pathologic sequelae of immunity is fragile and can easily be tipped towards harm for the host. The matter of immune privilege and surveillance of the CNS/PNS compartments and the role of the blood-brain barrier (BBB) and blood nerve barrier (BNB) makes this even more complex. Our understanding of the pathogenesis of many post-infectious manifestations of various microbial agents remains elusive, especially in the diverse African setting. Our exploration and better understanding of the neuroimmunology of some of the infectious diseases that we encounter in the continent will go a long way into helping us to improve their management and therefore lessen the burden. Africa is diverse and uniquely poised because of the mix of the classic, well described, autoimmune disease entities and the specifically "tropical" conditions. This review explores the current understanding of some of the para- and post-infectious autoimmune manifestations of CNS and PNS diseases in the African context. We highlight the clinical presentations, diagnosis and treatment of these neurological disorders and underscore the knowledge gaps and perspectives for future research using disease models of conditions that we see in the continent, some of which are not uniquely African and, where relevant, include discussion of the proposed mechanisms underlying pathogen-induced autoimmunity. This review covers the following conditions as models and highlight those in which a relationship with COVID-19 infection has been reported: a) Acute Necrotizing Encephalopathy; b) Measles-associated encephalopathies; c) Human Immunodeficiency Virus (HIV) neuroimmune disorders, and particularly the difficulties associated with classical post-infectious autoimmune disorders such as the Guillain-Barré syndrome in the context of HIV and other infections. Finally, we describe NMDA-R encephalitis, which can be post-HSV encephalitis, summarise other antibody-mediated CNS diseases and describe myasthenia gravis as the classic antibody-mediated disease but with special features in Africa.

Mitochondrial bioenergetics in ocular fibroblasts of two myasthenia gravis cases

Myasthenia gravis (MG) is a rare, treatable, antibody-mediated disease characterized by fatigable muscle weakness of extraocular muscles (EOMs) and non-ocular skeletal muscles. The antibodies are directed against muscle-endplate proteins, most frequently the acetylcholine receptor (AChR) alpha-subunit. Although most MG patients respond to immunosuppressive treatment, some individuals, frequently with African-genetic ancestry, develop treatment-resistant ophthalmoplegia (OP-MG). Although the underlying pathogenetic mechanisms of OP-MG remain unknown, experimental rodent models of MG showed upregulation of genes involved in oxidative metabolism in muscles. EOMs are highly dependent on oxidative metabolism. We opportunistically sampled EOM-tendons of two rare OP-MG patients (and non-MG controls) undergoing re-alignment surgery, and established ocular fibroblast cultures. Metabolic assays were performed on these live cells to assess real-time differences in energy metabolism. To study the cellular bioenergetic profiles in the context of MG, we exposed the cultures to homologous 5% MG sera for 24 h, vs. growth media, from two independent MG patients (with circulating AChR-antibodies) and five controls without MG, and estimated the fold change in oxygen consumption rates in response to three compounds which inhibit different mitochondrial chain complexes. Quantitative PCR (qPCR) was performed in cells before and after MG sera exposure, to assess transcript levels of mitochondrial genes, PDK4, ANGPTL4 and UCP3, which were altered in experimental MG. In response to the mitochondrial stressors, basal oxidative metabolism parameters were similar between OP-MG and control fibroblasts (p = 0.81). However, after exposure to MG sera, bioenergetic parameters (oxygen consumption rate as an indicator of oxidative phosphorylation; extracellular acidification rate as an indicator of glycolysis), were induced to higher levels in OP-MG fibroblasts compared to controls (2.6-fold vs 1.5-fold; p = 0.031) without evidence of mitochondrial insufficiency in the OP-MG ocular fibroblasts. In support of the bioenergetic responses to the same MG sera, gene transcripts of PDK4 and ANGPLT4 in ocular fibroblasts also showed significant upregulation (p ≤ 0.041), but similarly in OP-MG and control cases. Taken together we showed similar basal and metabolic adaptive responses after exposure to mitochondrial inhibitors in ocular fibroblasts derived from OP-MG cases and controls, although the OP-MG cells showed greater activation in response to MG conditions. These pilot results in orbital-derived tissues provide support for myasthenic-induced changes in cellular metabolism and evidence that orbital fibroblasts may be useful for dynamic bioenergetic assessments.

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Orbital fibroblasts may be useful for dynamic bioenergetic assays.

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Orbital-fibroblast cultures showed shifts in oxidative metabolism induced by homologous myasthenic sera.

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Altered bioenergetic adaptation was induced by MG sera in orbital fibroblasts from ophthalmoplegic MG patients compared to controls.

The Epidemiology and Phenotypes of Ocular Manifestations in Childhood and Juvenile Myasthenia Gravis: A Review

Myasthenia gravis (MG) appears to have a similar incidence among adult populations worldwide. However, epidemiological and phenotypic differences have been noted among children and juveniles with MG. We reviewed the literature on childhood- and juvenile-onset MG among different populations, with the focus on ocular involvement, antibody profiles, the genetic susceptibility to juvenile MG phenotypes, the use of immune treatments, and the reported responses of extraocular muscles to therapies. Although epidemiological studies used different methodologies, reports from Asia, compared to Europe, showed more than two-fold higher proportions of prepubertal onset (before 12 years) vs. postpubertal-onset juveniles with MG. Compared to European children, ocular MG was 4-fold more frequent among Asian children, and 2–3-fold more frequent among children with African ancestry both in prepubertal and postpubertal ages at onset. These results suggest genetic influences. In Asia, HLA-B^*46 and DRB1^*09 appeared overrepresented in children with ocular MG. In Europe, children with MG had a significantly higher rate of transforming from ocular to generalized disease and with an overrepresentation of HLADRB1^*04. Although treatment regimens vary widely and the responses to immune therapies of the ocular muscles involved in MG were generally poorly described, there were indications that earlier use of steroid therapy may have better outcomes. Reports of treatment-resistant ophthalmoplegia may be more frequent in African and Asian juvenile MG cohorts compared to Europeans. Genetic and muscle gene expression studies point to dysregulated muscle atrophy signaling and mitochondrial metabolism pathways as pathogenetic mechanisms underpinning treatment-resistant ophthalmoplegia in susceptible individuals. In conclusion, phenotypic differences in juveniles with ocular manifestations of MG were evident in different populations suggesting pathogenetic influences. Treatment responses in MG-associated ocular disease should attract more careful descriptive reports. In MG, extraocular muscles may be vulnerable to critical periods of poor force generation and certain individuals may be particularly susceptible to developing treatment-resistant ophthalmoplegia. The development of prognostic biomarkers to identify these susceptible individuals is an unmet need.

[Clinical and paraclinical profile of autoimmune myasthenia gravis in Ouagadougou, Burkina Faso]

INTRODUCTION

Certain differences in the epidemiological, clinical, paraclinical and evolution profiles of autoimmune myasthenia gravis (AIMG) are increasingly described in patients according to geographic origins. The present study was carried out in order to help characterize the socio-demographic, clinical and paraclinical profile of AIMG in Ouagadougou, Burkina Faso.

PATIENTS AND METHODS

This was a cross-sectional, descriptive, multicenter, hospital study carried out in Ouagadougou (Burkina Faso), over a period of 5 years 6 months, from March 2015 to September 2019. The study concerned all patients who had a clinical symptomatology suggestive of myasthenia gravis, associated with the presence in the serum of anti-AChR Ab and / or anti-MuSK Ab and / or the presence of a >10% decrement in electroneuromyography and / or a positive therapeutic test for oral anticholinestherasics. Sociodemographic, clinical and paraclinical variables, were analyzed.

RESULTS

A total of 25 patients (15 women and 10 men), were included. The young adult form was predominant (20 cases). The median time between the first symptoms and the diagnosis was 28.4 months +/- 44.8 (2 - 217 months). Diplopia and/or ptosis (80%) and dysphonia (72%) were the most frequent revealing clinical presentations. On admission, 7 patients (28%) had a moderate generalized form (MGFA class III) and 9 patients (36%) had a severe to very severe generalized form (MGFA class IV to V). Plasma Ab assays were performed in 17 patients (68%): anti-RACh Ab were positive in 11 patients (64.7%) and anti-MuSK Ab in 3 patients (14.3%). Thoracic CT revealed thymus hyperplasia in 12 patients (48%), thymoma in 5 patients (20%). Hyperthyroidism was associated in 2 patients (8%).

CONCLUSION

AIMG in Ouagadougou, Burkina Faso is marked by delayed diagnosis, a predominance in young women, severe generalized forms and a high frequency of plasma anti-MuSK Ab. This profile appears to be different from that of Caucasian patients. Collaborative studies in the sub-Saharan region on AIMG in general populations are needed.

A Comparison of Clinical, Electro-Diagnostic, Laboratory, and Treatment Outcome Differences in a Cohort of HIV-Infected and HIV-Uninfected Patients With Myasthenia Gravis

There is limited literature comparing the clinical parameters and treatment outcomes in HIV-infected and HIV-uninfected myasthenia gravis (MG) patients. The aim of the study was to investigate the clinical differences and treatment outcomes in the two categories of patients, particularly the safe use of immunosuppressive therapy in immunocompromised patients. The study was a retrospective analysis of medical records of MG patients from the neuromuscular unit at Inkosi Albert Luthuli Central Hospital in Kwa-Zulu Natal between 2003 and 2019. One hundred and seventy-eight (178) patients fulfilled the clinical criteria for MG. Twenty-four (13.4%) were HIV-infected and 154 (86.5%) were HIV-uninfected. There were 116 (65%) females, median 45 years, (IQR 40–62), 90 (50.5%) black African, 66 (37%) Indian, 20 (11.2%) white, and 2 (1.1%) of mixed ancestry. In the HIV-infected cohort, 20 (87%) had generalized MG, 12 (50%) bulbar, and 14 (60.9%) respiratory onset MG, 12 (50%) presented with MG Foundation of America (MGFA) class five diseases at diagnosis, six (25%) presented with MG crisis during the 5-year follow-up. Thirteen (54%) of the HIV-infected group required rescue therapy using (plasma exchange or IV immunoglobulin) combined with pulse cyclophosphamide compared with 17 (11%) in the HIV-uninfected cohort, respectively. At 5 years, 8 (33%) of the HIV-infected group remained refractory to treatment compared with 10 (6.5%) HIV-uninfected cohort, respectively. No adverse events were documented in HIV-infected patients receiving combination rescue therapy (PLEX or IVIG combined with IV cyclophosphamide). In conclusion HIV-infected MG patients are more likely to require combination rescue therapy with PE/IVIG and IV cyclophosphamide compared with those who were HIV-uninfected. No side effects were documented in the HIV-infected group receiving the above therapy.

Epidemiology of Ocular Manifestations in Autoimmune Disease

The global prevalence of autoimmune diseases is increasing. As a result, ocular complications, ranging from minor symptoms to sight-threatening scenarios, associated with autoimmune diseases have also risen. These ocular manifestations can result from the disease itself or treatments used to combat the primary autoimmune disease. This review provides detailed insights into the epidemiological factors affecting the increasing prevalence of ocular complications associated with several autoimmune disorders.

Age at sampling and sex distribution of AChRAb vs. MuSKAb myasthenia gravis in a large Greek population

OBJECTIVE

Myasthenia gravis (MG) is a typical B-cell-mediated neuromuscular junction disease that can be classified into seropositive and seronegative subtypes. Association of patients' age at sampling and sex with the two major seropositive MG subcategories, i.e., MGs linked to antibodies directed against the acetylcholine receptor (AChRAb) and against the muscle-specific kinase (MuSKAb), has not been compared in a large population.

METHODS

We performed a retrospective analysis of samples from patients with MG in Greece who underwent neurochemical diagnostic evaluation between January 2, 2013, and August 31, 2016.

RESULTS

Overall, 1620 adult (623 male and 997 female patients; male-to-female ratio = 0.62) and 51 pediatric patients were found to be seropositive for MG. The distributions in both male and female patients were bimodal in the total and AChRAb MG cases but not in the total MuSKAb MG cases. Significant differences in the age at sampling distribution between the male and female adult patients were observed only in the AChRAb MG subtype. Significant differences between the AChRAb and MuSKAb MG categories were noted in the mean age values (60.10 and 51.49 years, respectively, for female and 65.69 and 56.19 years, respectively, for male adult patients).

CONCLUSION

Our findings confirm an uneven profile of age at sampling and sex between the AChRAb and MuSKAb MG cases in a large population. Future mechanistic studies can elucidate the cause of these differences. Moreover, clinical studies can explore how such differences can affect MG treatment and prognosis.

Determinants of Suboptimal Outcome Following Thymectomy in Myasthenia Gravis

Background

Response to thymectomy in myasthenia gravis (MG) is influenced by various patient-, disease-, and therapy-related factors.

Methods

Retrospective analysis of 128 patients with MG who underwent maximal thymectomy over 15 years was done to identify the determinants of suboptimal clinical outcome.

Results

Among the 128 patients, 62 (48.4%) were females with a mean age of 38.97 (12.29) years. Thymomatous MG occurred in 66 (51.6%). Overall improvement from preoperative status was noted in 88 (68.8%) patients after mean follow-up of 51.68 (33.21) months. The presence of thymoma was the major predictor of suboptimal clinical outcome (P = 0.001), whereas age, gender, preoperative disease severity, and seropositive status did not attain significance. Patients with better outcome had received higher steroid dose preoperatively (P = 0.035).

Conclusions

Suboptimal response after thymectomy occurred in one-third of MG patients, more commonly with thymomatous MG. Relationship of preoperative steroid therapy to remission merits evaluation.

Myasthenia Gravis: Epidemiology, Pathophysiology and Clinical Manifestations

Myasthenia gravis (MG) is an autoimmune neurological disorder characterized by defective transmission at the neuromuscular junction. The incidence of the disease is 4.1 to 30 cases per million person-years, and the prevalence rate ranges from 150 to 200 cases per million. MG is considered a classic example of antibody-mediated autoimmune disease. Most patients with MG have autoantibodies against the acetylcholine receptors (AChRs). Less commonly identified autoantibodies include those targeted to muscle-specific kinase (MuSK), low-density lipoprotein receptor-related protein 4 (Lrp4), and agrin. These autoantibodies disrupt cholinergic transmission between nerve terminals and muscle fibers by causing downregulation, destruction, functional blocking of AChRs, or disrupting the clustering of AChRs in the postsynaptic membrane. The core clinical manifestation of MG is fatigable muscle weakness, which may affect ocular, bulbar, respiratory and limb muscles. Clinical manifestations vary according to the type of autoantibody, and whether a thymoma is present.

Tuberculosis in Myasthenia Gravis patients on immunosuppressive therapy in a high-risk area: Implications for preventative therapy

Data regarding the risk of tuberculosis (TB) in myasthenia gravis (MG) patients receiving immunosuppressive therapy is limited, and the benefit of TB preventative therapy in these patients is uncertain. We audited observational data collected at an MG clinic in South Africa over a ~ 10-year period, of cases who received immunosuppressive therapy. The total time that the cohort was at risk (patient-years) was used as the denominator to calculate TB incidence after immunosuppressive therapy initiation. Multivariate logistic regression analysis was performed to identify differences between patients who did, and those who did not, develop TB. Of 480 cases, only two received TB preventative therapy when starting immunotherapy. Seventeen of 282 (6%) patients tested, were HIV-infected. With a median follow-up of 3.6 years (interquartile range 1;7.5), 13 (3%) patients (all HIV-uninfected) developed TB (38% within 12 months of starting immunosuppressive therapy). The incidence rate of TB in the study population (≤401/100000 person-years) was not higher than that for the hospital's catchment area during the same period (>500/100000 population). The maximum dose of prescribed prednisone was higher in patients who developed TB compared to those who did not (median: 0.6 mg/kg/day vs 0.4; 0.002); Odds ratio for TB increased 1.26-fold for every 0.1 mg/kg/day increase in maximum dose (p = 0.001). In our TB endemic setting, receiving immunosuppressive therapy was not associated with excess TB in MG patients. Preventative therapy may be considered in those who are at greatest risk of developing TB and receiving high-dose prednisone.

Early onset myasthenia gravis in a Malawian woman: Challenges in managing myasthenia gravis in a low-resource setting

Myasthenia gravis is a rare autoimmune disease, which presents with ocular or generalised symptoms. Few publications describe its prevalence in African populations. We describe a young woman who was diagnosed with myasthenia gravis in a Malawian public hospital and outline the challenges encountered in managing this condition in a low-resource setting.

The epidemiology of myasthenia gravis

Neuromuscular junction (NMJ) disorders include several dysfunctions that ultimately lead to muscle weakness. Myasthenia gravis (MG) is the most prevalent NMJ disorder with a highly polymorphic clinical presentation and many different faces. Being an autoimmune disease, MG correlates with the presence of detectable antibodies directed against the acetylcholine receptor, muscle-specific kinase, lipoprotein-related protein 4, agrin, titin, and ryanodine in the postsynaptic membrane at the NMJ. MG has become a prototype serving to understand both autoimmunity and the function of the NMJ better. The aim of this review is to synthesize some of the epidemiological data available. Epidemiological data regarding MG are important for postulating hypotheses regarding its etiology and facilitating the description of MG subtypes. Thus, adequate documentation through broad databases is essential. The incidence and prevalence of MG reported around the globe have been rising steadily and consistently over the past decades. Ethnic aspects, gender-related differences, and environmental risk factors have been described, implying that these might contribute to a specific phenotype, further suggesting that MG may be considered an umbrella term that covers several clinical entities.

Gene expression profiling of orbital muscles in treatment-resistant ophthalmoplegic myasthenia gravis

Background

Unbiased in silico approaches applied to genome-wide data prioritized putative functional gene variants associating with treatment-resistant ophthalmoplegic myasthenia gravis (OP-MG). Although altered expression of genes harbouring these variants, or associated pathways, were shown in patient-derived transdifferentiated-myocyte models, gene expression in orbital-derived muscle was required to test the validity of the predictions.

Methods

We sampled orbicularis oculi muscle (OOM) and one paralysed extraocular muscle (EOM) from six individuals with OP-MG during blepharoptosis and re-alignment surgeries, respectively. For controls, the OOMs were sampled from four individuals without myasthenia undergoing surgery for non-muscle causes of ptosis, and one non-paralysed EOM. Using a qPCR array, expression of 120 genes was compared between OP-MG and control OOMs, profiling putative “OP-MG” genes, genes in related biological pathways and genes reported to be dysregulated in MG cases or experimental MG models, and in EOMs of cases with strabismus. Normalization was performed with two stable reference genes. Differential gene expression was compared between OP-MG and control samples using the ΔΔCT method. Co-expression was analysed by pairwise correlation of gene transcripts to infer expression networks.

Results

Overall, transcript levels were similar in OOMs and EOMs (p = 0.72). In OOMs, significant downregulated expression of eight genes was observed in OP-MG cases compared with controls (> twofold; p ≤ 0.016), including TFAM, a mitochondrial transcription factor, and genes related to the following pathways: atrophy signalling; muscle regeneration and contraction; glycogen synthesis; and extracellular matrix remodelling. Several microRNAs, known to be highly expressed in EOMs, are predicted to regulate some of these genes. Co-expression analyses of gene-pairs suggested high interconnectedness of gene expression networks in OP-MG muscle, but not controls (r > 0.96, p < 0.01). Significant inverse directions of gene-pair correlations were noted in OP-MG versus controls OOM networks (r ≥ 0.92, p < 0.001) involving most OP-MG genes overlapping prominently with muscle atrophy/contractility and oxidative metabolism genes.

Conclusions

The gene expression in orbital muscles derived from OP-MG individuals compared with normal controls, support the pathogenic hypothesis previously generated from whole genome sequence analyses. Repression of gene transcripts in OP-MG orbital muscle implicate tissue-specific regulatory mechanisms, which may inform future biomarker discovery approaches.

Management Issues in Myasthenia Gravis Patients Living With HIV: A Case Series and Literature Review

South Africa is home to more than seven million people living with human immunodeficiency virus (HIV) and a high prevalence of tuberculosis. Human immunodeficiency virus–infected individuals may develop myasthenia gravis (MG), which raises questions regarding their management. An MG database, with 24 years of observational data, was audited for HIV-infected persons. Case reports of MG in HIV-infected persons were reviewed. We identified 17 persons with MG and HIV infection. All had generalized MG with a mean age at onset of 37.8 years. Eleven had acetylcholine receptor antibody–positive MG; one had antibodies against muscle-specific kinase. Six developed MG prior to HIV infection (mean CD4⁺ 361 cells/mm³); four worsened <6 months of starting antiretrovirals. Eleven developed MG while HIV-infected (mean CD4⁺ 423 cells/mm³); five presented with mild MG; three in MG crisis requiring rescue therapies (intravenous immune globulin or plasma exchange and/or intravenous cyclophosphamide). Two were diagnosed with HIV infection and MG at the same time. Fifteen required maintenance steroid-sparing immune therapies, predominantly azathioprine, or methotrexate. Plasma HIV viral loads remained below detectable levels on antiretrovirals during immunosuppressant treatment. Over the average follow-up of 6 years, 10 achieved minimal manifestation status, and the remainder improved to mild symptoms. Three cases had tuberculosis before MG, but none developed tuberculosis reactivation on immunosuppressive therapy; one used isoniazid prophylaxis. Herpes zoster reactivation during treatment occurred in one. Conclusions include the following: MG in HIV-infected patients should be managed similarly to individuals without HIV infection; half develop moderate–severe MG; MG symptoms may worsen within 6 months of antiretroviral initiation; safety monitoring must include plasma HIV viral load estimation. Isoniazid prophylaxis may not be indicated in all cases.

Autoantibodies in acquired myasthenia gravis: Clinical phenotype and immunological correlation

BACKGROUND

Data on antibody profile in myasthenia gravis (MG) from India are limited.

OBJECTIVES

To investigate antibody profile in patients with MG and their clinical correlates.

PATIENTS AND METHODS

Patients of MG (n = 85, M:F::1.1:1, mean age: 39.29 ± 17.3 years, mean symptom duration: 72.94 ± 91.8 months) were evaluated for clinical features, MG foundation of America (MGFA) score, response to treatment, and outcome at last follow-up. Antibodies to acetylcholine receptor (AChR), muscle-specific kinase (MUSK), titin and ryanodine receptor (RYR) were analysed using ELISA.

RESULTS

Based on the regional distribution of weakness, the cohort could be categorized as: generalized: 60, ocular: 16 and oculo-bulbar: 9. Sixty patients were followed up for a mean duration of 26.74 ± 13.8 months. Outcome at last follow-up was as follows: remission-22, no remission-33 and dead-5. AChR and MUSK antibodies were detected in 58 and 8 patients, respectively. Frequency of generalized MG, worse MGFA score during the disease course and thymomatous histology significantly correlated with presence of AChR-antibodies, though outcome at last follow-up was comparable between AChR-antibody positive and negative groups. Patients with MUSK antibodies had oculo-bulbar or generalized MG and frequent respiratory crisis, but majority improved or remitted with treatment. Titin antibodies were detected in 31.8% and RYR antibodies in 32.9%. Their presence did not correlate with age at onset of MG, severity or presence of thymoma.

CONCLUSION

This report highlights the spectrum of antibodies in MG in an Indian cohort. AChR-antibody positivity correlated with clinical severity. Outcome was good in majority of MUSK antibody-positive MG. The role of other antibodies, complementary vs epiphenomenon, remains open.

A review of the histopathological findings in myasthenia gravis: Clues to the pathogenesis of treatment-resistance in extraocular muscles

In myasthenia gravis autoantibodies target components of the neuromuscular junction causing variable degrees of weakness. In most cases, autoantibodies trigger complement-mediated endplate damage and extraocular muscles may be most susceptible. A proportion of MG cases develop treatment-resistant ophthalmoplegia. We reviewed publications spanning 65 years reporting the histopathological findings in the muscles and extraocular muscles of myasthenic patients to determine whether pathological changes in extraocular muscles differ from non-ocular muscles. As extraocular muscles represent a unique muscle allotype we also compared their histopathology in myasthenia to those in strabismus. We found that in myasthenia gravis, the non-ocular muscles frequently demonstrate neurogenic changes regardless of myasthenic serotype. Mitochondrial stress/damage was also frequent in myasthenic muscles and possibly more evident in muscle-specific kinase antibody-positive MG. Although myasthenia-associated paralysed extraocular muscles demonstrated prominent fibro-fatty replacement and mitochondrial alterations, these features appeared commonly in paralysed extraocular muscles of any cause. We postulate that extraocular muscles may be more susceptible than limb muscles to poor contractility as a consequence of myasthenia, resulting in a cascade of atrophy signaling pathways and altered mitochondrial homeostasis which contribute to the tipping point in developing treatment-resistant myasthenic ophthalmoplegia. Early strategies to improve force generation in extraocular muscles are critical.

Using Whole Genome Sequencing in an African Subphenotype of Myasthenia Gravis to Generate a Pathogenetic Hypothesis

Myasthenia gravis (MG) is a rare, treatable antibody-mediated disease which is characterized by muscle weakness. The pathogenic antibodies are most frequently directed at the acetylcholine receptors (AChRs) at the skeletal muscle endplate. An ophthalmoplegic subphenotype of MG (OP-MG), which is characterized by treatment resistant weakness of the extraocular muscles (EOMs), occurs in a proportion of myasthenics with juvenile symptom onset and African genetic ancestry. Since the pathogenetic mechanism(s) underlying OP-MG is unknown, the aim of this study was to use a hypothesis-generating genome-wide analysis to identify candidate OP-MG susceptibility genes and pathways. Whole genome sequencing (WGS) was performed on 25 AChR-antibody positive myasthenic individuals of African genetic ancestry sampled from the phenotypic extremes: 15 with OP-MG and 10 individuals with control MG (EOM treatment-responsive). Variants were called according to the Genome Analysis Toolkit (GATK) best practice guidelines using the hg38 reference genome. In addition to single variant association analysis, variants were mapped to genes (±200 kb) using VEGAS2 to calculate gene-based test statistics and HLA allele group assignment was inferred through "best-match" alignment of reads against the IMGT/HLA database. While there were no single variant associations that reached genome-wide significance in this exploratory sample, several genes with significant gene-based test statistics and known to be expressed in skeletal muscle had biological functions which converge on muscle atrophy signaling and myosin II function. The closely linked HLA-DPA1 and HLA-DPB1 genes were associated with OP-MG subjects (gene-based p < 0.05) and the frequency of a functional A > G SNP (rs9277534) in the HLA-DPB1 3'UTR, which increases HLA-DPB1 expression, differed between the two groups (G-allele 0.30 in OP-MG vs. 0.60 in control MG; p = 0.04). Furthermore, we show that rs9277534 is an HLA-DBP1 expression quantitative trait locus in patient-derived myocytes (p < 1 × 10^-3). The application of a SNP to gene to pathway approach to this exploratory WGS dataset of African myasthenic individuals, and comparing dichotomous subphenotypes, resulted in the identification of candidate genes and pathways that may contribute to OP-MG susceptibility. Overall, the hypotheses generated by this work remain to be verified by interrogating candidate gene and pathway expression in patient-derived extraocular muscle.

Exome sequencing identifies novel dysferlin mutation in a family with pauci-symptomatic heterozygous carriers

BACKGROUND

We investigated a South African family of admixed ancestry in which the first generation (G1) developed insidious progressive distal to proximal weakness in their twenties, while their offspring (G2) experienced severe unexpected symptoms of myalgia and cramps since adolescence. Our aim was to identify deleterious mutations that segregate with the affected individuals in this family.

METHODS

Exome sequencing was performed on five cases, which included three affected G1 siblings and two pauci-symptomatic G2 offspring. As controls we included an unaffected G1 sibling and a spouse of one of the G1 affected individuals. Homozygous or potentially compound heterozygous variants that were predicted to be functional and segregated with the affected G1 siblings, were further evaluated. Additionally, we considered variants in all genes segregating exclusively with the affected (G1) and pauci-symptomatic (G2) individuals to address the possibility of a pseudo-autosomal dominant inheritance pattern in this family.

RESULTS

All affected G1 individuals were homozygous for a novel truncating p.Tyr1433Ter DYSF (dysferlin) mutation, with their asymptomatic sibling and both pauci-symptomatic G2 offspring carrying only a single mutant allele. Sanger sequencing confirmed segregation of the variant. No additional potentially contributing variant was found in the DYSF or any other relevant gene in the pauci-symptomatic carriers.

CONCLUSION

Our finding of a truncating dysferlin mutation confirmed dysferlinopathy in this family and we propose that the single mutant allele is the primary contributor to the neuromuscular symptoms seen in the second-generation pauci-symptomatic carriers.

A patient with weakness and an abnormal chest radiograph: A case report

A 40-year-old black male presented to ICU after intubation for airway protection due to rapid onset of neck weakness and swallowing difficulty. His chest radiograph showed an unusual mediastinal opacity for which a computer tomography (CT) scan was done, confirming a mediastinal mass.

Gender and quality of life in myasthenia gravis patients from the myasthenia gravis foundation of America registry

INTRODUCTION

Quality of life (QOL) has been poorly characterized among patients with myasthenia gravis (MG) other than assessments performed within the clinical setting.

METHODS

Patients age ≥ 18 years who were diagnosed with MG and registered with the MG patient registry between July 1, 2013, and June 30, 2016, were included. Demographic information, disease related history, and QOL were compared between men and women using multivariable analysis.

RESULTS

A total of 1,315 subjects (827 women) were included. Women were significantly younger, had a younger age at symptom onset, and were more likely to have thymoma and thymectomy. The 15-item Myasthenia Gravis Quality of Life scale (MG-QOL15) was significantly worse in women. MG-QOL15 score was comparable between women who had thymectomy and men with or without thymectomy.

DISCUSSION

QOL among MG patients is worse in women compared with men, but this disparity is eliminated in women who have undergone thymectomy. Muscle Nerve, 2018.

Open source modular ptosis crutch for the treatment of myasthenia gravis

INTRODUCTION

Pharmacologic treatment of Myasthenia Gravis presents challenges due to poor tolerability in some patients. Conventional ptosis crutches have limitations such as interference with blinking which causes ocular surface drying, and frequent irritation of the eyes. To address this problem, a modular and adjustable ptosis crutch for elevating the upper eyelid in Myasthenia Gravis patients has been proposed as a non-surgical and low-cost solution.

AREAS COVERED

This paper reviews the literature on the challenges in the treatment of Myasthenia Gravis globally and focuses on a modular and adjustable ptosis crutch that has been developed by the Medical Device Laboratory at the University of Cape Town.

EXPERT COMMENTARY

The new medical device has potential as a simple, effective and unobtrusive solution to elevate the drooping upper eyelid(s) above the visual axis without the need for medication and surgery. Access to the technology is provided through an open source platform which makes it available globally. Open access provides opportunities for further open innovation to address the current limitations of the device, ultimately for the benefit not only of people suffering from Myasthenia Gravis but also of those with ptosis from other aetiologies.

Extraocular Muscle Findings in Myasthenia Gravis Associated Treatment-Resistant Ophthalmoplegia

We report the histopathological and ultrastructural tissue analysis of extraocular muscle (EOM) obtained from a patient with seronegative myasthenia gravis (MG) with treatment-resistant ophthalmoplegia for 3.5 years. The EOM demonstrated predominantly myopathic features and ultrastructural evidence of mitochondrial dysfunction, but the most striking features were increased endomysial collagen and adipocyte replacement of muscle fibers. By contrast, control EOM from a patient undergoing strabismus surgery for a sensory exotropia in a nonseeing eye and a similar duration of deviation, showed normal muscle histology. Although the histopathological and ultrastructural findings largely resemble those of limb muscle in MG, the abundant endomysial collagen may be nonspecific and secondary to poor force generation as a result of chronic ophthalmoplegia.

Ocular presentation of myasthenia gravis: A natural history cohort

INTRODUCTION

There are limited data on the natural history of untreated myasthenia gravis (MG) with ocular presentation.

METHODS

We analyzed 93 patients from symptom onset who presented to the Birmingham Midlands Eye Centre (BMEC) between January 2004 and July 2015. We used multiple stepwise logistic regression to identify predictive factors of generalization and Kaplan-Meier analysis on time to generalization.

RESULTS

Forty-six percent of patients developed generalized symptoms during the study period. Median time to generalization was 7 months. Time to generalization was earlier in patients seropositive for acetylcholine receptor (AChR) antibody (median 5 months vs. 21 months, P < 0.0001) and bilateral ptosis at onset (P = 0.015). Multivariate analysis identified AChR seropositivity [hazard ratio (HR) 5.03; 95% confidence interval (CI) 1.48-17.14; P = 0.001] and disease onset < 50 years (HR 3.58; 95% CI 1.18-10.90; P = 0.035) as risk factors for generalization.

DISCUSSION

As patients were steroid-naive before generalization, our cohort approximated the natural history of the condition. Muscle Nerve 57: 622-627, 2018.

Exome sequencing identifies targets in the treatment-resistant ophthalmoplegic subphenotype of myasthenia gravis

Treatment-resistant ophthalmoplegia (OP-MG) is not uncommon in individuals with African genetic ancestry and myasthenia gravis (MG). To identify OP-MG susceptibility genes, extended whole exome sequencing was performed using extreme phenotype sampling (11 OP-MG vs 4 control-MG) all with acetylcholine receptor-antibody positive MG. This approach identified 356 variants that were twice as frequent in OP-MG compared to control-MG individuals. After performing probability test estimates and filtering variants according to those 'suggestive' of association with OP-MG (p < 0.05), only three variants remained which were expressed in extraocular muscles. Validation in 25 OP-MG and 50 control-MG cases supported the association of DDX17_delG (p = 0.014) and SPTLC3_insACAC (p = 0.055) with OP-MG, but ST8SIA1_delCCC could not be verified by Sanger sequencing. A parallel approach, using a semantic model informed by current knowledge of MG-pathways, identified an African-specific interleukin-6 receptor (IL6R) variant, IL6R c.*3043 T>C, that was more frequent in OP-MG compared to control-MG cases (p = 0.069) and population controls (p = 0.043). A weighted genetic risk score, derived from the odds ratios of association of these variants with OP-MG, correlated with the OP-MG phenotype as opposed to control MG. This unbiased approach implicates several potentially functional gene variants in the gangliosphingolipid and myogenesis pathways in the development of the OP-MG subphenotype.

Prevalence and clinical aspects of immigrants with myasthenia gravis in northern Europe

INTRODUCTION

Multiethnic studies can provide etiological clues toward the genetic and environmental influence of a disease. The aim of this study was to determine prevalence and clinical features of myasthenia gravis (MG) in immigrants compared with native patients in 2 population-based cohorts.

METHODS

This cross-sectional study included 843 MG patients (375 from Norway and 468 from the Netherlands). Ethnic background was defined by questionnaires.

RESULTS

Among the participating MG patients, 163 of 843 (19.3%) were first or second generation immigrants, mainly from Europe, Asia, and South America. No marked prevalence differences were found between immigrants and native ethnic groups. MG with muscle specific kinase antibodies and MG with thymoma were more frequent in Asian MG immigrants compared with other ethnic groups (8% vs. 0-4%; P < 0.001 and 21% vs. 6-10%; P < 0.001), respectively.

CONCLUSIONS

Our findings indicate that Asian immigrant MG patients carry genetic factors or environmental/lifestyle factors which contribute to their specific phenotype, even after migration. Muscle Nerve 55: 819-827, 2017.

Characteristics Of acetylcholine-receptor-antibody-negative myasthenia gravis in a South African cohort

INTRODUCTION

In this study we determined the frequencies of antibodies (Abs) directed against muscle-specific kinase (MuSK) and lipoprotein receptor-related protein 4 (LRP4) in the sera of a South African cohort with acetylcholine receptor (AChR)-antibody-negative generalized MG and determined outcomes to therapies.

METHODS

Sera negative by commercial AChR radioimmunoassay (RIA) were tested by MuSK RIA (n = 30; 2006-2012) and AChR, MuSK, and LRP4 RIA with or without cell-based assays (CBA) (n = 53; 2012-2015).

RESULTS

AChR-Abs were detected in 4 of 53 and MuSK-Abs in 20 of 83 (24%) cases. Thirty-six of 53 (68%) were triple seronegative (triple-SNMG) for MuSK, AChR, and LRP4-Abs. When compared with triple-SNMG, individuals with MuSK-MG had a younger onset age (P = 0.008), a greater likelihood of African genetic ancestry (P = 0.008), and 4-fold higher odds of reaching MGFA grade IVB/V (P = 0.018), but were also 9-fold more likely to reach at least minimal manifestations status after ≥12 months of therapy (P = 0.003).

CONCLUSIONS

Individuals with African genetic ancestry and severe bulbar/respiratory AChR-Ab-negative MG are likely to have MuSK-MG, but most respond favorably to maintenance immunotherapies. Muscle Nerve 54: 1023-1029, 2016.

Clinical features of patients with Myasthenia gravis from the Henan province, China

INTRODUCTION

Myasthenia gravis (MG) occurs globally, and many studies have indicated that there are regional differences in epidemiology, biomarkers, and prognosis of MG.

METHODS

A total of 478 patients with MG who visited hospitals in the Henan Province between January 2010 and February 2014 were included. Age, gender, age at onset, serum antibody, thymus pathology, treatment information, and Myasthenia Gravis Foundation of America (MGFA) classification were assessed.

RESULTS

Compared with previous reports from other areas, we found some differences in MG patients from Henan. The proportion of childhood MG in our study was lower than other reports of Oriental patients with MG. There seems to be an association between onset age, muscle involvement, and acetylcholine receptor antibody levels. Thymectomy improved the symptoms in 78.5% of thymectomy-treated patients.

CONCLUSIONS

These differences are likely related to geographical, environmental, and ethnic differences. Understanding these differences will help us to define more specific treatment.

The African-387 C>T TGFB1 variant is functional and associates with the ophthalmoplegic complication in juvenile myasthenia gravis

Although extraocular muscles are commonly affected by myasthenia gravis (MG) at presentation, a treatment-resistant ophthalmoplegic complication of MG (OP-MG) occurs in younger patients with African-genetic ancestry. In MG, pathogenic antibodies activate complement-mediated muscle damage and this may be potentiated in some OP-MG cases because of relative deficiency of decay-accelerating factor/CD55. Extending this argument, we hypothesized that OP-MG individuals may harbor African-specific polymorphisms in key genes influencing extraocular muscle remodeling. We screened the regulatory region of the transforming growth factor beta-1 (TGFB1) gene encoding the cytokine pivotal in muscle healing responses. We show the frequency of an African-specific polymorphism TGFB1 c.-387 T (rs11466316) among South Africans with African-genetic ancestry is higher than 1000 Genomes African controls (17.2% vs 4.8%; P<1 × 10(-7)), and associates with juvenile OP-MG (28%; P=0.043). Further, TGFB1 -387 C>T is functional because it represses the TGFB1 promoter construct basal activity by fivefold, and OP-MG fibroblasts (-387 C/T or T/T) have lower basal TGFB1 mRNA transcripts compared with controls (-387 C/C)(P=0.001). Co-transfections with Sp1 show less responsiveness of the -387 T promoter compared with wild-type -387 C (P=0.015). Our findings suggest that population-specific alleles may lower TGFB1 expression, thereby influencing OP-MG susceptibility by inhibiting extraocular muscle CD55 upregulation and/or altered endplate remodeling.

Clinical profile of patients with myasthenia gravis followed at the University Hospital, Federal University of Minas Gerais

OBJECTIVE

to determine the clinical profile of patients with myasthenia gravis (MG); followed at the Neuromuscular Diseases Clinic of the University Hospital, Federal University of Minas Gerais, Brazil, and to compare it with other Brazilian case series.

METHODS

sociodemographic and clinical data were collected from patients, and a systematic literature review performed, focusing on national studies on the clinical profile of MG patients.

RESULTS

sixty nine patients were enrolled in the study. Fifty five (91%) subjects were female and the mean age (SD) was 37.6 (± 11.4) years. The mean disease duration was 14.1 years. Regarding treatment, prednisone was the most used strategy (64%), followed by the use of azathioprine (43%). There was no difference between thymectomized (42) and non-thymectomized (27) patients regarding disease severity and medication use.

CONCLUSION

clinical and socio-demographic features of this MG sample from a University-based clinic resemble those reported in other Brazilian series and in the international literature.

The effects of prednisone and steroid-sparing agents on decay accelerating factor (CD55) expression: implications in myasthenia gravis

Decay accelerating factor (DAF) expression at the muscle endplate is an important defence against complement-mediated damage in myasthenia gravis. Previously we implicated the c.-198C>G DAF polymorphism with the development of treatment-resistant myasthenia-associated ophthalmoplegia by showing that the C>G DAF polymorphism prevented lipopolysaccharide-induced upregulation of lymphoblast DAF. We postulated that drugs used in myasthenia gravis may increase the susceptibility of extraocular muscles to complement-mediated damage and studied their effects on endogenous DAF using patient-derived lymphoblasts as well as mouse myotubes. We show that prednisone repressed C>G DAF expression in lymphoblasts and increased their susceptibility to cytotoxicity. Methotrexate, but not azathioprine or cyclosporine, increased DAF in C>G lymphoblasts. In mouse myotubes expressing wild-type Daf, prednisone also repressed Daf expression. Although cyclosporine, azathioprine, and methotrexate increased muscle Daf levels when used alone, upon co-treatment with prednisone only azathioprine maintained myotube Daf levels close to basal. Therefore, prednisone negatively influences DAF expression in C>G lymphoblasts and in myotubes expressing wild-type Daf. We speculate that myasthenic individuals at risk of developing the ophthalmoplegic complication, such as those with C>G DAF, may have inadequate endogenous levels of complement regulatory protein protection in their extraocular muscle in response to prednisone, increasing their susceptibility to complement-mediated damage.

Association of transforming growth factor β-1 (TGFB1) regulatory region polymorphisms with myasthenia gravis-related ophthalmoparesis

We investigated the association of an ophthalmoplegic complication developing in African myasthenia gravis (MG) subjects with polymorphisms in the regulatory region of TGFB1. We found significant associations with several putative functional single nucleotide polymorphisms (SNPs) (including two novel SNPs) that potentially alter transcription factor binding. Our data support a hypothesis that altered TGFB1 regulation may predispose individuals who harbour these SNPs to developing ophthalmoplegia as a result of increased TGF-β1 driven myofibrosis as a consequence to complement-mediated damage.

A single-blinded trial of methotrexate versus azathioprine as steroid-sparing agents in generalized myasthenia gravis

Background

Long-term immunosuppression is often required in myasthenia gravis (MG). There are no published trials using methotrexate (MTX) in MG. The steroid-sparing efficacy of azathioprine (AZA) has been demonstrated after 18-months of starting therapy. However, AZA is considered expensive in Africa. We evaluated the steroid-sparing efficacy of MTX (17.5 mg weekly) compared with AZA (2.5 mg/kg daily) in subjects recently diagnosed with generalized MG by assessing their average monthly prednisone requirements.

Methods

The primary outcome was the average daily prednisone requirement by month between the two groups. Prednisone was given at the lowest dose to manage MG symptoms and adjusted as required according to protocol. Single-blinded assessments were performed 3-monthly for 2-years to determine the quantitative MG score and the MG activities of daily living score in order to determine those with minimal manifestations of MG.

Results

Thirty-one subjects (AZA n = 15; MTX n = 16) satisfied the inclusion criteria but only 24 were randomized. Baseline characteristics were similar. There was no difference between the AZA- and MTX-groups in respect of prednisone dosing (apart from months 10 and 12), in quantitative MG Score improvement, proportions in sustained remission, frequencies of MG relapses, or adverse reactions and/or withdrawals. The MTX-group received lower prednisone doses between month 10 (p = 0.047) and month 12 (p = 0.039). At month 12 the prednisone dose per kilogram bodyweight in the MTX-group (0.15 mg/kg) was half that of the AZA-group (0.31 mg/kg)(p = 0.019).

Conclusions

This study provides evidence that in patients with generalized MG methotrexate is an effective steroid-sparing agent 10 months after treatment initiation. Our data suggests that in generalized MG methotrexate has similar efficacy and tolerability to azathioprine and may be the drug of choice in financially constrained health systems.

Trial registration

SANCTR:DOH-27-0411-2436

Myasthenia gravis in Ceará, Brazil: clinical and epidemiological aspects

A retrospective chart review was performed on patients diagnosed as having myasthenia gravis in Ceará State, Brazil and who were followed from October 1981 to June 2009. Clinical and epidemiologic aspects were evaluated. In this work, 122 patients were studied, of whom 85 (69.7%) were females and 37 (30.3%) were males. The disease duration ranged from five months to 50 years (8.9±8.1 years). Age at the first symptoms varied from 0 to 74 years (31.9±14.4 years). The first main symptoms and signs were ptosis, diplopia and limb weakness. Generalized myasthenia was the most common clinical presentation, but 5.1% (n=6) persisted as ocular myasthenia. Thymectomy was performed in 42.6% (n=52) of myasthenic patients. A thymoma was present in 10 patients. Serum acetylcholine receptor (AChR) antibodies were present in 80% (n=20) of specimens tested. The data presented are similar to those of studies performed in other countries.

A functional SNP in the regulatory region of the decay-accelerating factor gene associates with extraocular muscle pareses in myasthenia gravis

Complement activation in myasthenia gravis (MG) may damage muscle endplate and complement regulatory proteins such as decay-accelerating factor (DAF) or CD55 may be protective. We hypothesize that the increased prevalence of severe extraocular muscle (EOM) dysfunction among African MG subjects reported earlier may result from altered DAF expression. To test this hypothesis, we screened the DAF gene sequences relevant to the classical complement pathway and found an association between myasthenics with EOM paresis and the DAF regulatory region c.-198C>G SNP (odds ratio=8.6; P=0.0003). This single nucleotide polymorphism (SNP) results in a twofold activation of a DAF 5′-flanking region luciferase reporter transfected into three different cell lines. Direct matching of the surrounding SNP sequence within the DAF regulatory region with the known transcription factor-binding sites suggests a loss of an Sp1-binding site. This was supported by the observation that the c.-198C>G SNP did not show the normal lipopolysaccharide-induced DAF transcriptional upregulation in lymphoblasts from four patients. Our findings suggest that at critical periods during autoimmune MG, this SNP may result in inadequate DAF upregulation with consequent complement-mediated EOM damage. Susceptible individuals may benefit from anti-complement therapy in addition to immunosuppression.

Racial differences in myasthenia gravis in Alabama

Demographic, clinical, and laboratory features were compared in 235 white and African-American (AA) patients with myasthenia gravis (MG) at the University of Alabama at Birmingham Neuromuscular Disease Clinic from May 2003 to January 2008. Seventy nine percent of patients were white. Acetylcholine receptor antibody was positive in 71% of white patients and in 59% of AA. In patients with seronegative generalized MG, the rate of positive muscle-specific tyrosine kinase antibody (MuSK-Ab) was significantly higher in AA than it was in whites (50% in AA vs. 17% in whites). Ocular MG was seronegative in 75% of AA patients. In AA, MG occurred earlier and more frequently in females, whereas, in whites, disease onset was later and more common in males. Another significant difference was a higher percentage of abnormality on repetitive nerve stimulation in AA. There was also a tendency for more severe forms of MG in AA. There are racial differences in MG between whites and AA in Alabama. These racial differences highlight the need to study biological factors in the pathogenesis of MG and to assess different approaches in diagnosis and treatment.

Myasthenic crisis

Myasthenic crisis is a life-threatening medical emergency requiring early diagnosis and respiratory assistance. It can affect between one-fifth and one-third of all patients with generalized autoimmune myasthenia gravis. Myasthenic crisis is to be distinguished from other causes of acute neuromuscular paralysis which in most cases, can be achieved clinically. High dose corticosteroids in combination with plasma exchange or immunoglobulin are the cornerstone of treatment for this fully reversible cause of neuromuscular paralysis.

The MGTX experience: challenges in planning and executing an international, multicenter clinical trial

We present our experience planning and launching a multinational, NIH/NINDS funded study of thymectomy in myasthenia gravis. We highlight the additional steps required for international sites and analyze and contrast the time investment required to bring U.S. and non-U.S. sites into full regulatory compliance. Results show the mean time for non-U.S. centers to achieve regulatory approval was significantly longer (mean 13.4+/0.96 [corrected] months) than for U.S. sites (9.67+/0.74 [corrected] months; p=0.003, [corrected] t-test). The delay for non-U.S. sites was mainly attributable to Federalwide Assurance certification and State Department clearance.

Myasthenia gravis: presentation and outcome in 104 patients managed in a single institution

BACKGROUND AND OBJECTIVES

Few studies have attempted to delineate the clinical profile of myasthenia gravis (MG) among people of Arab ancestry. Therefore, we sought to clarify the clinical profile, the outcome of treatment and the role of thymectomy in non-thymomatous MG in Saudi Arabia.

PATIENTS AND METHODS

We retrospectively studied 104 patients followed over a mean period of 7.2 years (range, 1 to 22 years) at the King Khaled University Hospital, Riyadh, Saudi Arabia. Disease outcomes were compared among thymectomized and non-thymectomized patients according to the post-intervention status criteria of the Myasthenia Gravis Foundation of America (MGFA).

RESULTS

Age of onset was 22.5+/-9.3 years (meanA+/-SD) in females and 28.2+/-15.9 years in males, with peaks in the second and third decades among females and the third and fourth decades among males. At diagnosis, a majority of patients had moderate generalized weakness, equivalent to MGFA class III severity. After medical treatment with or without thymectomy, 9.6% of all patients had achieved complete stable remission, 3.8% had pharmacological remission, 27.9% had minimal manifestations, 23.1% were improved, 20.2% were unchanged and 15.4% were worse. Only thymectomized patients without a thymoma achieved remission, a significant benefit over those who had no thymectomy (P=.02).

CONCLUSION

MG presents at a younger age among Saudi Arabs compared to other racial groups. Thymectomy conferred significant benefits towards achievement of remission.