Thyroiditis in myasthenia gravis

Three out of 40 patients with myasthenia gravis had chronic thyroiditis. The thyroid disease preceded the neuromuscular disorder in two patients, while the third developed a slowly progressive hypothyreosis during the course of the myasthenia. One patient had an initial thyrotoxicosis with subsequent development of hypothyreosis. Of the remaining 37 patients, two had enlarged thyroid glands, positive family history of thyroid disease and antibodies to thyroid globulin, but were euthyreot.     

Recurrent transverse myelitis, myasthenia gravis, and autoantibodies.

A 45-year-old man with a longstanding diagnosis of myasthenia gravis presented with four episodes of transverse myelitis in 5 years. Each episode improved after treatment with steroids. Laboratory studies revealed no evidence of multiple sclerosis or a structural spinal lesion. He had antinuclear and anti-DNA antibodies and the HLA-A1, B8, DR3 haplotype known to be associated with certain autoimmune diseases. We propose an autoimmune cause for the recurrent episodes of myelitis.     

HLA antigens and acetylcholine receptor antibody in the subclassification of myasthenia gravis in Hong Kong Chinese.

Thirty seven Chinese adults and 23 children in Hong Kong with myasthenia gravis were tested for HLA-A and -B antigens and acetylcholine receptor (AChR) antibody. HLA BW46 had a significantly increased prevalence in patients with juvenile onset ocular myasthenia gravis. Only one third of the juvenile ocular patients had AChR antibodies and the titres were generally low. In the adult patients taken as a whole there was a non-significant increase in the prevalence of HLA B5 and HLA B15. HLA BW46 was more prevalent in adult patients without AChR antibody and less prevalent in patients with AChR antibody but the findings were not statistically significant. It is suggested that ocular myasthenia gravis is determined by a pathological mechanism for which susceptibility is determined by HLA BW46. There was a strong correlation between ocular myasthenia gravis and Graves' disease in the adult patients. The possibility that ocular myasthenia gravis is accentuated by a BW46-associated predisposition to ocular Graves' disease is considered.     

Role of virus for the induction of myasthenia gravis

Virus has been suggested as an etiological agent in myasthenia gravis. In this investigation 36 patients with the clinical diagnosis of myasthenia gravis were tested for antibodies against ornithosis, mycoplasma pneumoniae and 16 viral antigens. Rabbits with experimentally induced autoimmune myasthenia gravis were similarly tested. There was no overall correlation to any microorganism, which might have suggested the involvement of a viral infection in the pathogenesis of the disease. Neither was there any difference in incidence of antibodies in female patients carrying the HLA B8 antigen, an antigen which is associated with myasthenia gravis, as compared to HLA B8 negative individuals.     

HLA antigens and myasthenia gravis in Japan

Recent studies have noted an increased association of the histocompatibility antigen HLA-B8 with myasthenia gravis in Caucasian patients.The HLA types of 63 Japanese patients with myasthenia were compared to those of 271 controls. The present study was designed to assess correlations between HLA antigens, sex, age at onset, the presence of autoantibodies and thymic morphology.HLA-B12 was increased in Japanese patients, especially females with early age at onset, and in addition it was significantly correlated with thymic hyperplasia. HLA-B5 was frequently found in the patients with thymoma. Statistically the most frequent haplotype found in this disease was HLA-A10–HLA-B12.     

Familial autoimmune myasthenia gravis: report of four families.

Four families each with two patients with autoimmune myasthenia gravis or related conditions are reported. All clinical forms of myasthenia gravis were represented and different disease types were found within the same family. Either one or two generations could be affected and no association with a single HLA haplotype was found. The frequency of familial autoimmune myasthenia gravis is very low and the genetic factors involved seem to be different from MHC genes.     

HLA,anti-DNA,and complement in myasthenia gravis

Twenty-seven patients (18 females and 9 males) with myasthenia gravis were HLA-A, -B, -C, and -D typed, and the results were analyzed with relation to evidence of immunodeficiency, thymic disease, and associated autoimmune processes. An association of A1, B8, and DRW3 appeared to identify a group of 8 females with higher mean anti-DNA, lower mean C4, and lower mean E. coli antibody titer than other females in whom CW4 (with or without BW35) was common (6 of the remaining 10 females were in this category). Antiacetylcholine receptor (anti-AChR) autoantibody and reduced serum lgM and isohemagglutinin titers were not clearly related to particular HLA specificities. These results suggest that HLA-A1, -B8, -DRW3, and -CW4 may be related to associated phenomena rather than playing a major role in the development of anti-AChR and myasthenia gravis.     

Transmission of maternal muscle-specific tyrosine kinase (MuSK) to offspring: report of two cases

Familial occurrence of myasthenia gravis is uncommon and reports of maternal transmission of muscle-specific tyrosine kinase (MuSK) antibody myasthenia are rarer still. We report two families with maternal transmission of MuSK antibody myasthenia gravis to the offspring by different mechanisms. The first family demonstrates transmission genetic susceptibility of inheriting myasthenia gravis from MuSK antibodies, whereas the second one demonstrates transplacental transmission of MuSK antibodies at birth.     

Strong association of HLA BW46 with juvenile onset myasthenia gravis in Hong Kong Chinese.

The HLA antigen distribution and thyroid autoantibody status of 27 Chinese children in Hong Kong with juvenile onset myasthenia gravis have been compared with 110 healthy university students from the same population. Twenty-four of the patients had ocular myasthenia. There was a significantly increased prevalence of HLA BW46 in the patients compared with controls (67% vs 26.4%, p less than 0.005) indicating that BW46 confers a relative risk of 5.6 for juvenile onset myasthenia gravis in Chinese children. The increased prevalence of BW46 was not associated with thyroid autoimmunity in the patients although the antigen is known to be associated with thyrotoxicosis in Chinese. The possibility that BW46 confers protection against the development of acetyl-choline receptor antibodies in Chinese patients is discussed. One patient had the Caucasian antigen B8 and the question whether defective immune response genes were introduced into the Chinese through Caucasian admixture is raised.     

Immunogenetic heterogeneity and associated autoimmune disorders in myasthenia gravis: a population-based survey in the province of Ferrara, northern Italy

Introduction - The well-established relationship between myasthenia gravis (MG) and HLA antigens varies among different ethnic groups. In Caucasians B8 and/or DR3 alleles have been found associated with young MG women without thymoma and with high titres of acetylcholine-receptor antibody (AChR Ab). An increased frequency of haplotype HLA-A3, B7 and/or DR2 has been observed in older MG patients with low AChR Ab levels. So far, there is no convincing evidence for an association between a specific haplotype HLA and ocular MG or MG with thymoma. MG subjects often show other concurrent autoimmune disorders suggesting a more general inherited predisposition to autoimmunity. We performed a community-based study to verify the HLA-A, B, C, DR and DQ profile on ethnically homogeneous MG patients and with the aim to estimate the frequency of concurrent autoimmune diseases and to compare HLA phenotypes to autoimmune status in different MG patients groups. Methods - Forty-seven patients, living in the province of Ferrara, were followed-up in our neurologic department and typed for HLA Antigens. In addition a set of immunological laboratory tests was performed. Results - We found a trend towards an increased B8 and DR3 frequencies in total affected population; an association between B8 allele and early onset of generalized MG sustained by thymic hyperplasia. The DR3 allele is statistically associated with the presence of additional autoimmune disorders. Conclusions - Our data support the hypothesis of a genetically-based heterogeneity of the disease and show an increased prevalence of associate autoimmune conditions in MG patients.     

Autoantibody formation after bone marrow transplantation. Comparison between acetylcholine receptor antibodies and other autoantibodies and analysis of HLA and Gm markers

Clinical myasthenia gravis has been reported in an increased frequency after bone marrow grafting. The number of bone marrow transplanted patients making IgG autoantibodies directed against the autoantigens cardiolipin, SS-B (La) and thyroglobulin was found to be significantly lower as compared to the autoantigen acetylcholine receptor protein. The occurrence of antibodies to single-stranded DNA was found in a lower frequency than acetylcholine receptor antibodies but the difference was not statistically significant. Antibodies to cardiolipin were frequently observed prior to grafting. The G1m1,2 and G3m5 phenotype frequency did not differ in individuals who developed receptor antibodies from that found in the normal population. Analysis of HLA antigens in this patient group revealed no association to HLA B8/DR3 or B35/DR1. This may indicate that the etiology of myasthenia gravis induced by bone marrow grafting differs as compared with the spontaneous form of myasthenia gravis and the penicillamine-induced disease.     

Three cases of myasthenia gravis from one family with variations in clinical features and serum antibodies

Myasthenia gravis, an autoimmune disorder affecting neuromuscular transmission, is mainly sporadic while familial cases are very rare. Usually familial myasthenia gravis cases have uniform clinical symptoms as well as serum anti-acetylcholine receptor antibodies. Interestingly, in our cases varying clinical types of myasthenia gravis and seropositive/seronegative anti-acetylcholine receptor antibodies coexisted in the same family. The mother and her daughter both had ocular myasthenia gravis, detectable anti-acetylcholine receptor antibodies and non-detectable anti-muscle-specific kinase antibodies, and good responses to medications. The son displayed ocular symptoms at the onset, and then progressed into a generalized form after 1 year. His serum anti-acetylcholine receptor antibodies and anti-muscle-specific kinase antibodies were both negative. Neither corticosteroids nor thymectomy alleviated his symptoms. Human leukocyte antigen DQA1*0301 allele sharing by the three patients may be involved in their genetic susceptibility to myasthenia gravis, and subtle differences in human leukocyte antigen DQB1 alleles may be associated with their variations in clinical features and serum antibodies.     

Predictive value of serum anti-C1q antibody levels in experimental autoimmune myasthenia gravis

Components of the complement cascade and circulating immune complexes play important roles in both experimental autoimmune myasthenia gravis and myasthenia gravis in humans. Thus far, no serological factor has been identified to predict the clinical severity of either myasthenia gravis. Upon immunization with acetylcholine receptor, levels of complement factors C1q, C3 and CIC increase with time in sera from C57BL/6 (B6) mice. Both these and plasma samples from myasthenia gravis patients also contain anti-C1q antibodies. The serum levels of anti-C1q antibodies but not C1q, C3 and CIC are significantly correlated with the clinical severity in the experimental myasthenia mice. However, this correlation is not observed in myasthenia gravis patients.     

The role of antibodies in myasthenia gravis

Myasthenia gravis is an autoimmune disease associated with antibodies directed to the postsynaptic acetylcholine receptor. These antibodies reduce the number of receptors. Autoantibodies against AChR and other muscle antigens can be used for the diagnosis of myasthenia gravis and related disorders. The origin and the role of these antibodies in the disease are discussed. Experimental autoimmune myasthenia gravis, an experimental model closely mimicking the disease, has provided answers to many questions about the role of antibodies, complement macrophages and AChR anchor proteins. Genetically modified anti-AChR antibodies may also be used in the future to treat myasthenia.     

Two cases of thymoma-associated myasthenia gravis without antibodies to the acetylcholine receptor

Thymoma-associated myasthenia gravis is considered a more severe disease compared with non-thymomatous myasthenia gravis and is generally associated with antibodies to the acetylcholine receptor (AChR-Ab). Even though a single case of thymoma-associated myasthenia gravis with anti-muscle specific kinase (MuSK) antibodies has been reported, to our knowledge, seronegative thymoma-associated myasthenia gravis has not been described. We report on two cases of this disease without antibodies to AChR or MuSK as a further evidence of the variability of myasthenia gravis in terms of antibody profile and thymic pathological findings.     

HLA type is not indicative for the effect of thymectomy in myasthenia gravis.

The frequency of HLA types in a selected group of 40 patients with myasthenia gravis in relation to the effect of thymectomy and also to gender, and thymus histology was studied. As generally described we found a significant increase in the frequency of HLA-A1, HLA-B8, HLA-DR3 and HLA-DQ2 in the total group. There were no further differences between subgroups of patients, which demonstrates that HLA type is not indicative for the effect of thymectomy in myasthenia gravis.     

Autoimmunity in ocular and generalised myasthenia gravis

Restricted ocular myasthenia gravis (OMG) and generalised myasthenia gravis (GMG) have been shown to differ in a number of respects. In OMG, anti-acetylcholine receptor, antistriational and antinuclear antibodies were rare relative to their frequency in GMG. In contrast, antithyroid antibodies and a history of thyroid disease were much more prevalent in OMG than in GMG. OMG was not associated with the female predominance seen in GMG and appeared to be relatively common in some races rather than others. It is suggested that different pathogenetic mechnisms are responsible for these two forms of MG.     

Ocular myasthenia gravis coincident with thyroid ophthalmopathy

Graves' disease and myasthenia gravis are both auto-immune diseases and the coexistence of these two diseases is well recognized. Myasthenia gravis is more frequent in patients with thyroid disease. Here we present a case of thyroid ophthalmopathy and ocular myasthenia.     

Striational antibodies in myasthenia gravis: reactivity and possible clinical significance

Myasthenia gravis is an autoimmune disease caused, in most cases, by antibodies attaching to the acetylcholine receptor. Some myasthenia gravis patients have antibodies that bind in a cross-striational pattern to skeletal and heart muscle tissue sections (striational antibodies). These antibodies react with epitopes on the muscle proteins titin and ryanodine receptor, are found mainly in sera of patients with thymoma and late-onset myasthenia gravis, and may correlate with myasthenia gravis severity. Their presence may predict an unsatisfactory outcome after thymectomy. The detection of titin and ryanodine receptor antibodies provides more specific clinical information than the immunofluorescent demonstration of striational antibodies.     

Myasthenia gravis, pernicious anemia, and Hashimoto's thyroiditis

A 68-year-old woman with clinical, electromyographic, and pharmacologic evidence of myasthenia gravis experienced increasing proximal and bulbar muscular weakness. The diagnosis of pernicious anemia was established by typical abnormalities in the peripheral blood and bone marrow aspirate, the serum B12 level, by results of the Schilling test, and by the presence of serum parietal cell antibody. The diagnosis of Hashimoto's thyroiditis was established by the presence of diffuse thyroid enlargement, microsomal thyroid antibodies, an increased thyroid stimulating hormone level, and depressed T2 and T4 levels.