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 11,717 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The objective of this study was to analyse the mutations of the acetylcholine receptor (AChR) delta subunit gene (CHRND) in a patient with sporadic congenital myasthenic syndrome (CMS). Mutations in various genes encoding proteins expressed at the neuromuscular junction may cause CMS. Mutations of AChR subunit genes lead to end-plate AChR deficiency or to altered kinetic properties of the receptor. Mutations in the alpha, beta and delta subunits of the AChR are less frequent than mutations of the epsilon subunit; mutations in these subunits leading to AChR deficiency are often associated with a severe phenotype. A sporadic patient from Germany was studied, who presented with an early onset CMS associated with feeding difficulties, ptosis, a moderate general weakness responsive to anticholinesterase treatment and recurrent episodes of respiratory insufficiency provoked by infections. The CHRND gene was screened for mutations by RFLP, long-range PCR and sequence analysis. Subsequently, we conducted functional studies of AChR mutants co-transfected with rapsyn in HEK 293 cells. Heterozygously to a 2.2 kb microdeletion disrupting the CHRND gene, we identified a novel point mutation in the long cytoplasmic loop, CHRND E381K. The cytoplasmic loop of the AChR subunits is known to be essential for AChR-rapsyn co-clustering. We therefore studied the interaction of AChR containing the CHRND E381K mutation with rapsyn by evaluating expression and co-localization of rapsyn and mutated AChR subunits in co-transfected HEK 293 cells. Interestingly, the mutated receptor showed severely reduced cluster formation compared with the wild-type receptor. In contrast, the corresponding amino acid substitution in the cytoplasmic loop of the AChR epsilon (CHRNE E376K) as well as a recently reported CMS mutation affecting this domain (CHRNE N436del) had no impact on cluster formation. CHRND mutations are a rare cause for CMS but should be considered in patients with a severe, early onset disease form, clinically resembling a rapsyn phenotype with recurrent episodic apnoeas. Our results suggest that impairment of AChR-rapsyn co-clustering--a well-known molecular mechanism for rapsyn mutations--could also result from mutations in the delta subunit. Introduction of the same mutation in the epsilon subunit had no effect on AChR clustering indicating a special role of the delta subunit in AChR-rapsyn interactions.
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PMID:CHRND mutation causes a congenital myasthenic syndrome by impairing co-clustering of the acetylcholine receptor with rapsyn. 1691 45

There have been reported cases of children with histories of pauciarticular juvenile chronic arthritis (JCA) later developing myasthenia gravis (MG) as young adults. This is intriguing because it had been considered rare to diagnose a second autoimmune disease in a patient with pauciarticular JCA, unlike in those with adult-onset rheumatoid arthritis. We report a case of MG in a 20-year-old woman with a history of pauciarticular JCA. She presented with bilateral ptosis, weakness, and a history of dysphagia. The diagnosis was confirmed with positive serum acetylcholine receptor antibodies (2000 nm/L) and electromyography showing a decremental response to repetitive muscle stimulation. The patient's inflammatory arthritis was quiescent at diagnosis. The patient underwent a surgical thymectomy and was treated with pyridostigmine, intravenous immunoglobulin, and corticosteroids with a fluctuating clinical course. Previous cases have been reported of MG associated with this subtype of JCA, suggesting a connection in autoimmune pathology. The earlier recognition and management of MG in a patient with pauciarticular JCA presenting with weakness may improve the prognosis of this disease.
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PMID:Myasthenia gravis in a patient with pauciarticular juvenile chronic arthritis. 1704 84

A 25-year-old man with chronically progressive ptosis and bilateral ophthalmoplegia displayed fatigability and fluctuation of ptosis, an abnormal single-fiber electromyogram, and a markedly elevated acetylcholine receptor antibody level. Yet a muscle biopsy showed clear evidence of a mitochondrial cytopathy, and the clinical features did not improve after treatment with prednisone. This case emphasizes the difficulty in differentiating mitochondrial cytopathy from myasthenia gravis and points out that elevated acetylcholine receptor antibody levels may occur in nonmyasthenic conditions.
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PMID:Mitochondrial ophthalmoplegia with fatigable weakness and elevated acetylcholine receptor antibody. 1741 72

The Dandy-Walker syndrome (DWS) is a rare posterior fossa malformation. The DWS can occur associated with other brain or systemic malformations, but ocular abnormalities in this disease are rare and clinical findings mimicking myasthenia gravis have not been described to date. We report a 23-year-old woman who presented mild limitation of the ocular movements with progressive palpebral ptosis, which changed in intensity during the day. The investigation showed negative anti-acetylcholine receptor antibody, repetitive nerve stimulation and "Tensilon test", but the brain magnetic resonance image reveals DWS with hydrocephalus associated with callosal dysgenesis. The characteristic of disease, clinical manifestations and pathologic features, specially the clinical evaluation of ocular abnormalities in suspicion of DWS, including the MG in differential diagnosis are discussed.
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PMID:Dandy-Walker syndrome in adult mimicking myasthenia gravis. 1742 Aug 52

Dok ('downstream-of-kinase') family of cytoplasmic proteins play a role in signalling downstream of receptor and non-receptor phosphotyrosine kinases. Recently, a skeletal muscle receptor tyrosine kinase (MuSK)-interacting cytoplasmic protein termed Dok-7 has been identified. Subsequently, we and others identified mutations in DOK7 as a cause of congenital myasthenic syndromes (CMS), providing evidence for a crucial role of Dok-7 in maintaining synaptic structure. Here we present clinical and molecular genetic data of 14 patients from 12 independent kinships with 13 different mutations in the DOK7 gene. The clinical picture of CMS with DOK7 mutations is highly variable. The age of onset may vary between birth and the third decade. However, most of the patients display a characteristic 'limb-girdle' pattern of weakness with a waddling gait and ptosis, but without ophthalmoparesis. Respiratory problems were frequent. Patients did not benefit from long-term therapy with esterase inhibitors; some of the patients even worsened. DOK7 mutations have emerged as one of the major genetic defects in CMS. The clinical picture differs significantly from CMS caused by mutations in other genes, such as the acetylcholine receptor (AChR) subunit genes. None of the patients with DOK7 mutations had tubular aggregates in the muscle biopsy, implying that 'limb-girdle myasthenia (LGM) with tubular aggregates' previously described in literature may be a pathogenic entity distinct from CMS caused by DOK7 mutations.
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PMID:Phenotypical spectrum of DOK7 mutations in congenital myasthenic syndromes. 1743 81

Mutations in DOK7 have recently been shown to underlie a recessive congenital myasthenic syndrome (CMS) associated with small simplified neuromuscular junctions ('synaptopathy') but normal acetylcholine receptor and acetylcholinesterase function. We identified DOK7 mutations in 27 patients from 24 kinships. Mutation 1124_1127dupTGCC was common, present in 20 out of 24 kinships. All patients were found to have at least one allele with a frameshift mutation in DOK7 exon 7, suggesting that loss of function(s) associated with the C-terminal region of Dok-7 underlies this disorder. In 15 patients, we were able to study the clinical features in detail. Clinical onset was usually characterized by difficulty in walking developing after normal motor milestones. Proximal muscles were usually more affected than distal, leading to a 'limb-girdle' pattern of weakness; although ptosis was often present from an early age, eye movements were rarely involved. Patients did not show long-term benefit from anticholinesterase medication and sometimes worsened, and where tried responded to ephedrine. The phenotype can be distinguished from 'limb-girdle' myasthenia associated with tubular aggregates, where DOK7 mutations were not detected and patients respond to anticholinesterase treatments. CMS due to DOK7 mutations are common within our UK cohort and is likely to be under-diagnosed; recognition of the phenotype will help clinical diagnosis, targeted genetic screening and appropriate management.
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PMID:Clinical features of the DOK7 neuromuscular junction synaptopathy. 1745 75

An 18-year-old man presented with progressive weakness of proximal muscles with prominent diurnal variation for 3 months. He had bilateral ptosis since his childhood without diurnal variation or double vision. Neurological examination showed involvement of levator palpebrae superioris and lateral rectus muscles bilaterally. The plasma glucose after 75 gm glucose load was 302 mg/dL. The electrophysiological study revealed myopathic pattern and a decremental response in repetitive nerve stimulation. The plasma lactate was elevated and the muscle biopsy showed numerous ragged-red fibers. Serum acetylcholine receptor antibody assay was positive. We diagnosed myasthenia gravis with mitochondrial myopathy.
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PMID:Mitochondrial myopathy associated with myasthenia gravis in a young man. 1746 3

A 7-year-old girl was diagnosed with generalized myasthenia gravis and became steroid-dependent. Dose of prednisolone could not be reduced to < 2 mg/kg/day on alternate days, despite adverse effects. Thymectomy was avoided. Oral tacrolimus was initiated at 1.0 - 1.3 mg/kg/day. Ptosis and weakness of the lingual and pharyngeal muscles began to ameliorate 2 weeks later, and disappeared within 2 months. Serum titer of anti-acetylcholine receptor antibody also declined. During the subsequent two years, remission was maintained although prednisolone was reduced to half the original dose. No adverse effects of tacrolimus were noted. This case suggests the usefulness of tacrolimus in the treatment of childhood myasthenia gravis.
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PMID:[A child with generalized myasthenia gravis successfully treated with tacrolimus]. 1763 89

A 54-year-old woman was admitted to our hospital because of diplopia, dysphagia, dropped head, and muscle weakness with easy fatigability. A neurological examination showed bilateral ptosis, ocular motility disorder, dysphagia, and weakness of the neck extensor muscles. Edrophonium and repetitive nerve stimulation tests of the thenar muscles showed positive results. The serum titer of anti-acetylcholine receptor antibody was negative. A thymoma was not detected in her chest CT. Finally, she was diagnosed with anti-MuSK antibody-positive myasthenia gravis based on the high serum titer of anti-MuSK antibody (239 nmol/l). Her symptoms improved after administration of prednisolone. However, the symptoms were aggravated when the prednisolone dosage was reduced, and the titer of anti-MuSK antibody rose at the same time. We evaluated the possible association between changes in the severity of her clinical symptoms and the titer of the antibody during prednisolone therapy. It was revealed that the titer of the antibody was correlated to the severity of clinical symptoms expressed by a QMG (Quantitative Myasthenia Gravis) score. These findings indicate that monitoring the titer of anti-MuSK antibody can be useful for assessing disease activity as well as decision making during treatment.
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PMID:[Titer of anti-muscle-specific receptor tyrosine kinase (MuSK) antibody correlated with symptomatic improvement in response to corticosteroid therapy in a patient with anti-MuSK antibody-positive myasthenia gravis: a case report]. 1763 10

Ptosis is not a feature observed in amyotrophic lateral sclerosis (ALS). We describe two old women with bulbar-onset ALS and rapid progression, in whom ptosis and diplopia were noted. They did not improve on pyridostigmine or steroids. Antibodies against acetylcholine receptor were negative, thymoma was excluded, but neurophysiological showed marked neuromuscular transmission failure in orbicularis oculi. We discuss the association between ALS and ocular myasthenia gravis in these cases.
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PMID:Amyotrophic lateral sclerosis patients and ocular ptosis. 1792 Jan 89


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