No association of the HLA-DQ alleles with myasthenia gravis in Cuban patients

Myasthenia gravis (MG) is a neuromuscular disorder characterized by fatigability and weakness of striated muscles. Its association with HLA molecules is well known and varies depending on age, sex and the ethnicity of the patients. A case–control study was performed in 61 Cuban patients and 81 controls using polymerase chain reaction and sequence-specific primers of the HLA-DQA1/B1 alleles. The distribution of the HLA-DQ alleles individually and in a simple haplotype between patients and controls shows no statistically significance differences. This result could be due to the heterogeneity and ethnic admixture existing in Cuban population. These findings indicate that the association between a disease and a particular genetic region cannot be explained merely by similarities in the genetic background but involve environmental and immunological factors.     

Plasma-exchange in myasthenia gravis: a study in 20 patients

Twenty patients with myasthenia gravis (MG) of generalized 2A and 2B types according to the Ossermann classification were treated with a course of nine plasma exchanges (PE) every two days. Before starting of the course, at the fourth exchange, and at the end of the course, the muscle balance was assessed following a special protocol. Other functions, such as respiratory function, stapedial reflex, phonation, and electro-oculographic activity were assessed and a Desmedt test was done. Three patients showed complete remission of symptoms, 8 showed good improvement and 6 mild improvement. Three showed no improvement. In total 85% of patients gained from PE. The onset of improvement was rapid in all patients but in some it lasted only a short time while in others it persisted for several weeks and even months, without the need for immunosuppressive therapy.     

Analysis of the DYSF mutational spectrum in a large cohort of patients

Dysferlinopathies belong to the heterogeneous group of autosomal recessive muscular dystrophies. Mutations in the gene encoding dysferlin (DYSF) lead to distinct phenotypes, mainly Limb Girdle Muscular Dystrophy type 2B (LGMD2B) and Miyoshi myopathy (MM). Here, we analysed the mutational data from the largest cohort described to date, a cohort of 134 patients, included based on clinical suspicion of primary dysferlinopathy and/or dysferlin protein deficiency identified on muscle biopsy samples. Data were compiled from 38 patients previously screened for mutations in our laboratory (Nguyen, et al., 2005; Nguyen, et al., 2007), and 96 supplementary patients screened for DYSF mutations using genomic DHPLC analysis, and subsequent sequencing of detected variants, in a routine diagnostic setting. In 89 (66%) out of 134 patients, molecular analysis identified two disease causing mutations, confirming the diagnosis of primary Dysferlinopathy on a genetic basis. Furthermore, one mutation was identified in 30 patients, without identification of a second deleterious allele. We are currently developing complementary analysis for patients in whom only one or no disease-causing allele could be identified using the genomic screening procedure. Altogether, 64 novel mutations have been identified in this cohort, which corresponds to approximately 25% of all DYSF mutations reported to date. The mutational spectrum of this cohort significantly shows a higher proportion of nonsense mutations, but a lower proportion of deleterious missense changes as compared to previous series. (c) 2008 Wiley-Liss, Inc.     

Histiocytosis X of the thymus in association with myasthenia gravis

A patient with myasthenia gravis underwent thymectomy following the failure of medical treatment. The thymus was normal except for four nodules, which, on histologic and electron microscopic examination, were found to consist of proliferative clusters of Langerhans' cells characteristic of histiocytosis X. This patient therefore had two disease processes in which thymic abnormalities are frequently encountered, but their simultaneous occurrence in the same patient has not hitherto been documented. The case is briefly discussed in the context of current concepts of the pathogenesis of histiocytosis X and myasthenia gravis.     

Precipitation of auto-antibody in serum from patients with myasthenia gravis

Suitable means have been developed for the preparation of extracts of human or monkey skeletal muscle, which give precipitation with certain sera from patients with myasthenia gravis. These extracts are prepared in three solvents, namely, water, saline or sucrose. The water and saline extracts are the best for precipitation in fluid systems, conveniently carried out in capillary tubes. While all three types can be used for precipitation in gel diffusion, either double diffusion or immunoelectrophoresis, the sucrose extract is more convenient. In all these tests, the systems are to be incubated at 4°, and the results are to be read at 24 hours. This time limit is particularly important for the fluid precipitation, in order to avoid non-specific precipitation. With these precautions, it was found that no precipitation occurred with a large number of normal sera. Furthermore, only two out of about 100 sera from patients with various other diseases gave any precipitation. The precipitation antigen could not be found in extracts from a large number of other tissues, including heart, thymus and smooth muscle. Gel diffusion analysis revealed two major antigens and a minor antigen. Different precipitating myasthenic sera differ in their content of the respective antibodies. The antigenic material has not yet been chemically characterized, but the data suggest that it is not myosin or actomyosin.     

Immunoglobulin allotypes in myasthenia gravis patients with a thymoma

Gm and Km allotypes were examined in 29 myasthenia gravis patients with a thymoma and non-receptor skeletal muscle antibodies. The frequency of the phenotype Gm1,2,3;23;5,21 was significantly higher in the patients than in 292 healthy controls (P less than 0.01). Km allotype frequencies did not differ in patients and controls.     

A primary mediastinal Hodgkin's lymphoma with asymptomatic myasthenia gravis: a rare association

Myasthenia gravis (MG) is an autoimmune neuromuscular junction disorder that is frequently associated with other autoimmune diseases. It has been only rarely reported in association with thymic Hodgkin's lymphoma. We report a case of a 22-year-old man who presented with thoracic symptoms. Clinical examination was normal. Simple chest radiography showed a heterogeneous mediastinal mass. Thoracic computed tomography revealed an antero-superior mediastinal mass measuring 6 cm and invading the upper lobe of the left lung with parenchymal micronodules of the left lung and an involvement of mediastinal nodes. In order to consider a diagnosis of thymoma, electromyography was performed despite the fact that the patient was asymptomatic. This exam demonstrated signs specific of MG. After stabilising the MG with symptomatic therapies, surgical intervention was performed. Histological and immunohistochemical findings led to the diagnosis of thymic Hodgkin's lymphoma. The MG regressed completely after surgical removal of the lesion. The patient is currently receiving complementary chemotherapy. An association between asymptomatic MG and thymic Hodgkin's lymphoma has not been documented in the literature, and the present case appears to be the first reported. The pathogenesis of this association remains unknown. Some authors support a genetic origin, while others propose a hypothesis based on immunological studies. The treatment of thymic Hodgkin's lymphoma is based on Cotswold staging system. Nonetheless, MG generally regresses after surgical removal of the thymic lesion.     

Lymphocyte subpopulations in non-neoplastic thymus from myasthenia gravis patients.

Lymphocyte populations in non-neoplastic thymuses from fifteen patients with myasthenia gravis (MG) were examined. As in normal subjects, the great majority of thymic lymphocytes of MG patients are T cells. When MG thymuses were compared to normal glands, lower percentages of lymphocytes able to form E rosettes resistant to incubation at 37 degrees C (stable E rosettes) were found in MG thymuses. A negligible B cell content was detected in eight normal and in eight MG thymuses with absent or rare lymph follicles; but there was a substantial B cell presence in the thymuses of seven MG cases with thymic hyperplasia containing many germinal centres. Normal and MG thymuses contain the same percentage of lymphocytes bearing receptors for the Fc portion of IgM (TM). Moreover, the IgM Fc receptor was found mostly on cells which did not form stable E rosettes and did not bear surface immunoglobulin. The possible significance of these findings is discussed.     

Mutation spectrum in a large cohort of unrelated consecutive patients with hypertrophic cardiomyopathy

Defects in nine sarcomeric protein genes are known to cause hypertrophic cardiomyopathy (HCM). Mutation types and frequencies in large cohorts of consecutive and unrelated patients have not yet been determined. We, therefore, screened HCM patients for mutations in six sarcomeric genes: myosin-binding protein C3 (MYBPC3), MYH7, cardiac troponin T (TNNT2), alpha-tropomyosin (TPM1), cardiac troponin I (TNNI3), and cardiac troponin C (TNNC1). HCM was diagnosed in 108 consecutive patients by echocardiography (septum >15 mm, septal/posterior wall >1.3 mm), angiography, or based on a state after myectomy. Single-strand conformation polymorphism analysis was used for mutation screening, followed by DNA-sequencing. A total of 34 different mutations were identified in 108 patients: 18 mutations in MYBPC3 in 20 patients [intervening sequence (intron) 7 + 1G > A and Q1233X were found twice], 13 missense mutations in MYH7 in 14 patients (R807H was found twice), and one amino acid change in TPM1, TNNT2, and TNNI3, respectively. No disease-causing mutation was found in TNNC1. Cosegregation with the HCM phenotype could be demonstrated for 13 mutations (eight mutations in MYBPC3 and five mutations in MYH7). Twenty-eight of the 37 mutation carriers (76%) reported a positive family history with at least one affected first-grade relative; only eight mutations occurred sporadically (22%). MYBPC3 was the gene that most frequently caused HCM in our population. Systematic mutation screening in large samples of HCM patients leads to a genetic diagnosis in about 30% of unrelated index patients and in about 57% of patients with a positive family history.     

Autoimmunity in myasthenia gravis: a family study

The prevalence of autoantibodies to muscle, epithelial cells of calf thymus, thyroid, gastric parietal cells and antinuclear and rheumatoid factors has been studied in the sera of thirty-two patients with myasthenia gravis and their relatives.

Previous reports of an increased prevalence of autoantibodies in the sera of patients with myasthenia gravis have been confirmed and it has been shown that concurrent reactivity to muscle and thymus is closely correlated with the severity of the myasthenia and the presence of a thymoma, whereas no such correlation occurred with the other antibodies studied. None of the sera from relatives or spouses showed concurrent reactivity with thymus and muscle, and with the exception of one patient with pernicious anaemia, sera from patients with a variety of other diseases were also negative.

A slight increase in the prevalence of autoantibodies to thyroid and gastric components and antinuclear factor was found in first degree relatives of patients with myasthenia gravis; this could be accounted for by their aggregation in a few families.

     

Poly-autoimmunity in patients with myasthenia gravis: A single-center experience

Abstract

We evaluated the co-occurrence of autoimmune diseases (ADs) in a large population of myasthenia gravis (MG) patients from a single center. Our survey included 984 patients, 904 with anti-acetylcholine receptor antibodies and 80 with anti-muscle specific kinase antibodies. The anti-acetylcholine receptor positive population included patients with early-onset (age at onset ≤50 years), late-onset and thymoma-associated disease. Follow-up ranged 2–40 years. Two-hundred and fourteen ADs were diagnosed in 185 patients; 26 of them had two or more ADs in association with MG. Thyroid disorders were the most common and, together with vitiligo and thrombocytopenia, occurred in all disease subsets. Otherwise, there was a broad variability with partial overlap among patient groups. The highest rate of ADs was observed in early-onset patients, while clusters, i.e. 2 or more ADs other than MG in the same individual, were more common among thymoma cases. Thirty-four diseases were diagnosed at the same time, 88 occurred before and 92 after the onset of MG. On multivariate analysis, immunosuppressive treatment was the only independent variable which negatively influenced the risk of developing other ADs in our cohort.     

McArdle disease: the mutation spectrum of PYGM in a large Italian cohort

Deficiency of the muscle isozyme of glycogen phosphorylase is causative of McArdle disease or Glycogen storage disease type V (GSD-V), the most common autosomal recessive disorder of glycogen metabolism. The typical clinical presentation is characterized by exercise intolerance with cramps, and recurrent myoglobinuria. To date, 46 mutations in the PYGM gene have been detected in GSD-V patients. We report the mutational spectrum in 68 Italian patients. We identified 30 different mutations in the PYGM gene, including 19 mutations that have not been reported previously. The novel mutations include: eight missense mutations (c.475G>A, p.G159R; c.689C>G, p.P230R; c.1094C>T, p.A365E; c.1151C>A, p.A384D; c.1182C>T, p.R428C; c.1471C>T, p.R491C; c.2444A>C, p.D815A; c.2477G>C, p.W826S), two nonsense mutations (c.1475G>A, p.W492X; c.1627A>T, p.K543X), five splice site mutations (c.855 +1G>C; c.1092 +1G>A; c. 1093-1G>T; c.1239 +1G>A; c.2380 +1G>A), and four deletions (c.715_717delGTC, p.V239del; c.304delA, p.N102DfsX4; c.1970_2177del, p.V657_G726; c.2113_2114delGG, p.G705RfsX16). Whereas we confirmed lack of direct correlation between the clinical phenotype and the genotype, we also found that the so-called 'common mutation' (p.R50X) accounted for about 43% of alleles in our cohort and that no population-related mutations are clearly identified in Italian patients.     

Myasthenia gravis: familial occurrence. A study of 1100 myasthenia gravis patients

Eleven-hundred myasthenia gravis cases observed by the author in a period of 37 years are reviewed. The ratio of familial incidence was 4.23%. Transitory (neonatal) myasthenia in new-born babies should be separated from the familial cases. In familial myasthenia gravis both maternal and paternal line can occur. The majority of the cases are similar to the generalized, acquired myasthenia gravis, still there are some myasthenic familial congenital patients, too. Some rare instances are reported, among them a unique family with six sisters suffering from myasthenia gravis. Genetic line and HLA antigens' role are dealt with. Observation of familial myasthenia cases may contribute to the knowledge of the immunologic and clinicopathologic background of the disease.     

Familial myasthenia gravis: nine patients in two generations.

In two generations of a family followed up for 15 years, nine patients suffering from myasthenia gravis were observed. The family, being of special genetic importance, is unique in the literature.     

Tissue plasminogen activator involvement in experimental autoimmune myasthenia gravis: Aggravation and therapeutic potential

Tissue plasminogen activator (tPA), a component of the PA/plasmin system, is elevated in inflammatory areas and plays a role in inflammatory neurological disorders. In the present study we explored the involvement of tPA and the potential immunomodulatory activity of tPA in experimental autoimmune myasthenia gravis (EAMG). Mice deficient in tPA (tPA^−/−) present with a markedly more severe disease than wild type EAMG mice. In an attempt to treat EAMG with an 18aa peptide derived from the PA system inhibitor (PAI-1), designed to tether out the endogenous inhibitor, a significant suppression of disease severity was demonstrated. The more severe disease in tPA^−/− mice was accompanied by a higher level of anti-AChR antibodies and increased expression of B-cell markers. In view of the essential role of B-cell activating factor (BAFF) in B-cell maturation, the expression of BAFF family components was tested. An increase in BAFF and BAFF receptor was observed in EAMG tPA^−/− mice, whereas BCMA expression was reduced, consistent with the increased level of pathogenic antibodies and the more severe disease. Given the importance of T regulatory cells (Tregs) in EAMG, they were evaluated and their number was reduced in tPA^−/− mice, in which EAMG was aggravated, whereas following PAI-1dp treatment, Tregs were replenished and the disease was ameliorated. The results show the involvement of tPA in EAMG, implying a protective role for tPA in EAMG pathogenesis. The amelioration of EAMG by PAI-1dp treatment suggests that the PA system may be considered a potential site for therapeutic intervention in neuroimmune diseases.     

In situ production of interleukins in hyperplastic thymus from myasthenia gravis patients

We analyzed by in situ hybridization the expression of four interleukin genes (interleukin-beta [IL-1 beta], IL-6, IL-2, and interferon-gamma) in seven thymuses displaying a follicular hyperplasia. The seven thymuses were obtained from patients with myasthenia gravis. Interleukin-1 beta- and IL-6-producing cells were detected in similar amounts and with similar distributions: mainly in perifollicular areas and in the connective structures emerging from the septae at the site of cortex disruption. The comparison of in situ hybridization and immunohistochemical results suggested that thymic epithelial cells and/or perifollicular macrophages were responsible for this production. Interleukin-2-producing cells were detected in perifollicular areas and, to a lesser extent, inside follicles. They were clearly outnumbered by CD25-positive cells which were similarly distributed. Despite the expression of these molecular and immunohistochemical markers of T-cell activation, interferon-gamma-producing cells were extremely rare in myasthenic thymuses. The pattern of interleukin production (which was virtually absent in normal control thymuses) in myasthenic thymuses was different from that in benign hyperplastic lymph nodes. This interleukin production may play a role in the development of follicular hyperplasia in myasthenic thymuses, a phenomenon which is associated with the in situ production of autoantibodies.     

High recombinant interleukin-2 sensitivity of peripheral blood lymphocytes from patients with myasthenia gravis: correlations with clinical parameters

Myasthenia Gravis (MG) is an autoimmune disorder of neuromuscular transmission associated with antibodies (Ab) against acetylcholine receptor (AChR). Autoantibody production is a T-cell-dependent phenomenon perhaps caused by aberrant immunoregulation. So far, a possible role for immunoregulatory molecules has not been investigated in the pathogenesis of MG. Since interleukin-2 (IL-2) is able to induce peripheral blood mononuclear cell (PBMC) proliferation without a previous activating signal and to upregulate IL-2-receptor expression, we have evaluated the activation state of PBMC in patients with MG, by cytofluorographic analysis of CD25 expression and by testing their sensitivity to recombinant IL-2 (rIL-2) without any known previous stimulation. We found no significant difference in CD25 expression in a large group of patients compared to controls. However, proliferative responses to rIL-2 were significantly higher in MG patients than in controls. In MG, as in controls, this response was time- and dose-dependent, was inhibited by an anti-IL-2 receptor Ab and correlated with an increased percentage of CD25+ T cells after rIL-2 exposure. The response was greater in patients with a high anti-AChR Ab titer and a severe form of the disease, and in patients tested before thymectomy. Thus blood T cells in MG showed functional signs of preactivation (high sensitivity to rIL-2 alone) without detectable CD25 expression on fresh cells, raising the possibility of aberrant IL-2 receptor regulation and/or expression in MG T cells. Decreased sensitivity to rIL-2 after thymectomy, associated with general clinical improvement, suggests a role for activated cells originating from the thymus in the pathogenesis of MG, and is of clinical relevance in patient follow-up. Our findings also provide a new approach in the study of MG pathogenesis: the search for aberrant immunoregulation mechanisms linked to defects in lymphokine circuits.     

Complicating autoimmune diseases in myasthenia gravis: a review

Abstract

Myasthenia gravis (MG) is a rare autoimmune disease of skeletal muscle endplates. MG subgroup is relevant for comorbidity, but usually not accounted for. MG patients have an increased risk for complicating autoimmune diseases, most commonly autoimmune thyroid disease, systemic lupus erythematosus and rheumatoid arthritis. In this review, we present concomitant autoimmune disorders associated with the different MG subgroups, and show how this influences treatment and prognosis. Concomitant MG should always be considered in patients with an autoimmune disorder and developing new neuromuscular weakness, fatigue or respiratory failure. When a second autoimmune disorder is suspected, MG should be included as a differential diagnosis.     

Evaluation of pupil mobility in patients with myasthenia gravis

The aim of this study is to investigate the effect of Myasthenia Gravis (MG) on the Central Nervous System (CNS) and/or the smooth muscles of the iris through pupillometry. Sixteen recently diagnosed Myasthenic and sixteen non-Myasthenic subjects of matching age and gender underwent a pupillometric study of the effects of single flash stimuli of 24.6 candelas/m2 intensity and 20 msec duration. A significant decrease in Amplitude (p < 0.001), Maximum Constriction Velocity (p < 0.001) and especially Maximum Constriction Acceleration with a perfect discrimination ability (AUC= 1, p < 0.001). was observed in the Myasthenic compared to the non-Myasthenic subjects. In contrast, no significant difference was observed in Baseline Pupil Radius (R1) and 3.5 secs Percentage Recovery-Redilatation (R%) (p = 0.051 and p = 0.517, respectively). Of the parameters that are studied, R1 and R% are governed mainly by the action of the Sympathetic Nervous System (SNS) and the rest by the Parasympathetic Nervous System (ParNS), through Acetylcholine. The analysis of these parameters demonstrates that the SNS remains unaltered while the ParNS may be affected in MG. This post-synaptic cholinergic receptors' deficit may be central, within the CNS, or peripheral, related to the Neuromuscular Junction of the iris' sphincter.     

Plasmaperfusion on triptophan columns can improve the clinical outcome of patients affected with myasthenia gravis

Myasthenia Gravis (MG) is a neuromuscular disease often associated with thymic pathology due to neuromuscular transmission impairment by circulating antibodies directed against the cholinergic postsynaptic receptor on the neuromuscular junction (Anti-AchR-Ab). The treatment of MG includes cholinesterase inhibitors, steroids and thymectomy. Plasmapheresis can remove Anti-AchR-Ab but more recently plasma-perfusion (PP), a more specific apheresis for selective removal of noxious plasma components, has been developed. AIM OF THE STUDY: To study the effect of PP treatment, performed by using specific immunocolumns for Anti-AchR-Ab, on the clinical outcome of MG patients non-responder to steroid therapy or thymectomy. MATERIALS AND METHODS: We treated 8 patients suffering from severe MG by a cycle of 6 sessions of PP. We used columns containing triptophan as a specific ligand for Anti-AchR-Ab. In order to evaluate the effectiveness of treatment we used functional tests (muscular tests, respiratory function, electromyography) and laboratory tests (Anti-AchR-Ab; immunoglobulins, complement fractions, immunocomplexes). RESULTS: After one to three PP sessions, early clinical improvement in bulbar and respiratory symptoms were found in all patients and EMG showed improvement of neuromuscular transmission. Serum concentration of immunological markers decreased progressively and significantly during the treatment. Clinical improvements were progressive despite the tendency for Anti-AchR-Ab to reach initial values between one session and another. We observed no side effects due to the type of immunocolumns used. CONCLUSIONS: Triptophan columns appear to be able to remove large quantities of Anti-AchR-Ab and immunological markers from plasma. Our experience shows that PP performed using triptophan columns in patients suffering from severe MG provides good clinical results, improving patients' outcome, without any risk linked to the procedure.