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1.
Acta Neurol Belg ; 123(6): 2325-2335, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-37656362

RESUMO

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


Assuntos
Miastenia Gravis , Síndromes Miastênicas Congênitas , Criança , Feminino , Humanos , Síndromes Miastênicas Congênitas/diagnóstico , Síndromes Miastênicas Congênitas/genética , Síndromes Miastênicas Congênitas/tratamento farmacológico , Turquia , Miastenia Gravis/diagnóstico , Miastenia Gravis/genética , Miastenia Gravis/complicações , Debilidade Muscular , Receptores Colinérgicos/genética
2.
Adv Pediatr ; 70(1): 81-90, 2023 08.
Artigo em Inglês | MEDLINE | ID: mdl-37422299

RESUMO

Myasthenia gravis (MG) is a rare condition that impairs function at the neuromuscular junction of skeletal muscles, seen less commonly in children. Causes include autoimmune MG, congenital myasthenic syndromes, and transient neonatal myasthenia gravis. Symptoms of weakness, hypotonia, and fatigability can be reasonably explained by more common causes, thus children with MG disorders commonly experience delays in treatment with severe consequences. This leads to the progression of disease and serious complications including myasthenic crises and exacerbations. We describe 5 cases of MG, which illustrate clinical and genetic challenges in establishing diagnosis and subsequent consequences of delayed diagnosis.


Assuntos
Miastenia Gravis , Síndromes Miastênicas Congênitas , Recém-Nascido , Lactente , Criança , Humanos , Miastenia Gravis/terapia , Miastenia Gravis/tratamento farmacológico , Síndromes Miastênicas Congênitas/terapia , Síndromes Miastênicas Congênitas/tratamento farmacológico , Fadiga
3.
J Am Assoc Nurse Pract ; 35(8): 519-523, 2023 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-37141567

RESUMO

ABSTRACT: Congenital myasthenic syndrome (CMS) is a group of rare genetic disorders that mimics the symptoms of myasthenia gravis, but it is due to a genetic defect. We present a case of a male CMS patient, and the course of the disease through the years. The patient initially presented with generalized muscle weakness and difficulty swallowing. During the follow-up, he developed difficulty in chewing, bilateral external ophthalmoparesis with an almost full block of eye movements and bulbar syndrome. The case illustrates both the clinical heterogeneity and the progressive worsening of the symptoms of the disease over the years. The optimal treatment for CMS is based on the molecular defect and its localization in the neuromuscular junction. In our case, treatment with pyridostigmine resulted in good long-term control of symptoms. As a result of the patient's good compliance with treatment, he was not admitted to hospital because of respiratory distress. The lack of a unified protocol for the treatment of CMS highlights the need for a more personalized approach when dealing with patients with rare diseases.


Assuntos
Miastenia Gravis , Síndromes Miastênicas Congênitas , Humanos , Masculino , Mutação/genética , Miastenia Gravis/diagnóstico , Síndromes Miastênicas Congênitas/tratamento farmacológico , Síndromes Miastênicas Congênitas/genética , Síndromes Miastênicas Congênitas/diagnóstico , Brometo de Piridostigmina/uso terapêutico , Adulto , Resultado do Tratamento
4.
Int J Mol Sci ; 24(3)2023 Jan 23.
Artigo em Inglês | MEDLINE | ID: mdl-36768582

RESUMO

PURA-related neurodevelopmental disorders (PURA-NDDs) are a rare genetic disease caused by pathogenic autosomal dominant variants in the PURA gene or a deletion encompassing the PURA gene. PURA-NDD is clinically characterized by neurodevelopmental delay, learning disability, neonatal hypotonia, feeding difficulties, abnormal movements, and epilepsy. It is generally considered to be central nervous system disorders, with generalized weakness, associated hypotonia, cognitive and development deficits in early development, and seizures in late stages. Although it is classified predominantly as a central nervous syndrome disorder, some phenotypic features, such as myopathic facies, respiratory insufficiency of muscle origin, and myopathic features on muscle biopsy and electrodiagnostic evaluation, point to a peripheral (neuromuscular) source of weakness. Patients with PURA-NDD have been increasingly identified in exome-sequenced cohorts of patients with neuromuscular- and congenital myasthenic syndrome-like phenotypes. Recently, fluctuating weakness noted in a PURA-NDD patient, accompanied by repetitive nerve stimulation abnormalities, suggested the disease to be a channelopathy and, more specifically, a neuromuscular junction disorder. Treatment with pyridostigmine or salbutamol led to clinical improvement of neuromuscular function in two reported cases. The goal of this systematic retrospective review is to highlight the motor symptoms of PURA-NDD, to further describe the neuromuscular phenotype, and to emphasize the role of potential treatment opportunities of the neuromuscular phenotype in the setting of the potential role of PURA protein in the neuromuscular junction and the muscles.


Assuntos
Epilepsia , Deficiências da Aprendizagem , Síndromes Miastênicas Congênitas , Malformações do Sistema Nervoso , Transtornos do Neurodesenvolvimento , Humanos , Junção Neuromuscular , Síndromes Miastênicas Congênitas/tratamento farmacológico , Síndromes Miastênicas Congênitas/genética , Hipotonia Muscular/genética , Proteínas de Ligação a DNA/genética , Fatores de Transcrição/genética
7.
Nature ; 595(7867): 404-408, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-34163073

RESUMO

Congenital myasthenia (CM) is a devastating neuromuscular disease, and mutations in DOK7, an adaptor protein that is crucial for forming and maintaining neuromuscular synapses, are a major cause of CM1,2. The most common disease-causing mutation (DOK71124_1127 dup) truncates DOK7 and leads to the loss of two tyrosine residues that are phosphorylated and recruit CRK proteins, which are important for anchoring acetylcholine receptors at synapses. Here we describe a mouse model of this common form of CM (Dok7CM mice) and a mouse with point mutations in the two tyrosine residues (Dok72YF). We show that Dok7CM mice had severe deficits in neuromuscular synapse formation that caused neonatal lethality. Unexpectedly, these deficits were due to a severe deficiency in phosphorylation and activation of muscle-specific kinase (MUSK) rather than a deficiency in DOK7 tyrosine phosphorylation. We developed agonist antibodies against MUSK and show that these antibodies restored neuromuscular synapse formation and prevented neonatal lethality and late-onset disease in Dok7CM mice. These findings identify an unexpected cause for disease and a potential therapy for both DOK7 CM and other forms of CM caused by mutations in AGRIN, LRP4 or MUSK, and illustrate the potential of targeted therapy to rescue congenital lethality.


Assuntos
Proteínas Musculares/genética , Mutação , Síndromes Miastênicas Congênitas/tratamento farmacológico , Síndromes Miastênicas Congênitas/genética , Envelhecimento , Agrina/genética , Agrina/metabolismo , Animais , Animais Recém-Nascidos , Anticorpos/imunologia , Modelos Animais de Doenças , Feminino , Proteínas Relacionadas a Receptor de LDL/genética , Proteínas Relacionadas a Receptor de LDL/metabolismo , Masculino , Camundongos , Terapia de Alvo Molecular , Fibras Musculares Esqueléticas/química , Fibras Musculares Esqueléticas/metabolismo , Proteínas Musculares/química , Proteínas Musculares/metabolismo , Síndromes Miastênicas Congênitas/imunologia , Fosforilação , Fosfotirosina/genética , Fosfotirosina/metabolismo , Proteínas Proto-Oncogênicas c-crk/metabolismo , Receptores Proteína Tirosina Quinases/agonistas , Receptores Proteína Tirosina Quinases/genética , Receptores Proteína Tirosina Quinases/imunologia , Receptores Proteína Tirosina Quinases/metabolismo , Recidiva , Sinapses/metabolismo
8.
Neurology ; 95(20): e2781-e2793, 2020 11 17.
Artigo em Inglês | MEDLINE | ID: mdl-32907971

RESUMO

OBJECTIVE: To find determinants of the occurrence of repetitive compound muscle action potential (R-CMAP) and to assess the efficacy of channel blocker therapy in slow-channel congenital myasthenic syndrome (SCCMS). METHODS: Neurologic examination, EMG study, laboratory test, muscle biopsy, and next-generation and Sanger sequencing; literature review of reported patients with SCCMS, including EMG, kinetics of mutant acetylcholine receptors (AChRs), and response to therapy; and simulation of the decay phase of endplate potential (EPP) were performed. RESULTS: Three newly characterized and 57 reported patients with SCCMS with mutations of AChR subunits were included. In patients with R-CMAP, the length of channel opening bursts of mutant AChR was increased 8.68 ± 2.82 (mean ± SD)-fold compared to wild-type; in patients without R-CMAP, the length was increased 3.84 ± 0.65-fold (95% confidence interval 3.18-6.50, p = 0.000014). The EPP amplitude after refractory period of action potential in muscle fiber is above the threshold in patients with R-CMAP but below the threshold in patients without R-CMAP. In patients with good results from channel blocker therapy, treatment was initiated 11.60 ± 5.17 years after onset of symptoms; in patients with no to moderate benefit from channel blocker therapy, treatment was initiated 30.70 ± 12.72 years after onset (95% confidence interval -28.57 to -9.63, p = 0.00089). CONCLUSIONS: In SCCMS, the R-CMAP occurrence is related to the extent of prolongation of the opening episodes of mutant AChR channel. Channel blocker treatment is more effective the sooner it is started after the onset of symptoms. CLASSIFICATION OF EVIDENCE: This study provides Class IV evidence that channel blocker therapy in patients with SCCMS improves symptoms.


Assuntos
Inibidores da Colinesterase/farmacologia , Moduladores de Transporte de Membrana/farmacologia , Músculo Esquelético/fisiopatologia , Síndromes Miastênicas Congênitas/diagnóstico , Síndromes Miastênicas Congênitas/tratamento farmacológico , Adulto , Eletromiografia , Feminino , Humanos , Pessoa de Meia-Idade , Síndromes Miastênicas Congênitas/genética , Síndromes Miastênicas Congênitas/fisiopatologia , Linhagem , Brometo de Piridostigmina/farmacologia , Receptores Colinérgicos/genética , Adulto Jovem
9.
Hum Mutat ; 41(3): 619-631, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-31765060

RESUMO

MUSK encodes the muscle-specific receptor tyrosine kinase (MuSK), a key component of the agrin-LRP4-MuSK-DOK7 signaling pathway, which is essential for the formation and maintenance of highly specialized synapses between motor neurons and muscle fibers. We report a patient with severe early-onset congenital myasthenic syndrome and two novel missense mutations in MUSK (p.C317R and p.A617V). Functional studies show that MUSK p.C317R, located at the frizzled-like cysteine-rich domain of MuSK, disrupts an integral part of MuSK architecture resulting in ablated MuSK phosphorylation and acetylcholine receptor (AChR) cluster formation. MUSK p.A617V, located at the kinase domain of MuSK, enhances MuSK phosphorylation resulting in anomalous AChR cluster formation. The identification and evidence for pathogenicity of MUSK mutations supported the initiation of treatment with ß2-adrenergic agonists with a dramatic improvement of muscle strength in the patient. This work suggests uncharacterized mechanisms in which control of the precise level of MuSK phosphorylation is crucial in governing synaptic structure.


Assuntos
Mutação , Síndromes Miastênicas Congênitas/diagnóstico , Síndromes Miastênicas Congênitas/genética , Receptores Proteína Tirosina Quinases/genética , Receptores Colinérgicos/genética , Sinapses/genética , Agonistas de Receptores Adrenérgicos beta 2/farmacologia , Agonistas de Receptores Adrenérgicos beta 2/uso terapêutico , Alelos , Substituição de Aminoácidos , Animais , Sistemas CRISPR-Cas , Linhagem Celular , Análise Mutacional de DNA , Feminino , Marcação de Genes , Humanos , Camundongos , Modelos Moleculares , Conformação Molecular , Proteínas Musculares/metabolismo , Síndromes Miastênicas Congênitas/tratamento farmacológico , Síndromes Miastênicas Congênitas/metabolismo , Linhagem , Fosforilação , Receptores Proteína Tirosina Quinases/química , Receptores Proteína Tirosina Quinases/metabolismo , Receptores Colinérgicos/química , Receptores Colinérgicos/metabolismo , Relação Estrutura-Atividade , Sinapses/metabolismo
10.
Medwave ; 19(5): e7645, 2019.
Artigo em Inglês, Espanhol | LILACS | ID: biblio-1005855

RESUMO

INTRODUCCIÓN Los síndromes miasténicos congénitos son un grupo heterogéneo de desórdenes genéticos, caracterizados por una transmisión sináptica anormal en la placa neuromuscular. REPORTE Presentamos el caso de un paciente de dos años, varón, con hipotonía, ptosis palpebral y debilidad simétrica y de predominio proximal, características que aparecieron desde el nacimiento y que motivaron varias hospitalizaciones por neumonía e insuficiencia ventilatoria. Desde el inicio de la deambulación a los dos años, los padres notaron que la debilidad empeoraba por las tardes y con la actividad física repetida o prolongada. El examen físico a los dos años mostró ptosis palpebral, debilidad de predominio proximal y fatigabilidad con el esfuerzo sostenido. La electro-miografía evidenció decremento del 27% en el potencial de acción muscular compuesto. El análisis de tríos mostró heterocigosis compuesta por transmisión de dos mutaciones diferentes en el gen de rapsina, una ya conocida procedente del padre y la otra no reportada previa-mente, procedente de la madre. El paciente recibió piridostigmina obteniendo mejoría inmediata y logrando un desempeño óptimo en actividades escolares, deportivas y de la vida cotidiana. A la fecha, no ha presentado nuevos episodios de insuficiencia ventilatoria. CONCLUSIONES La debilidad de inicio neonatal y la fatigabilidad o agotamiento con el esfuerzo sostenido, con afección principalmente de los músculos con inervación troncal y con un decremento mayor al 10% en el potencial de acción muscular compuesto en la electromiografía, deben hacer sospechar en un síndrome miasténico congénito. Se revisan los puntos clínicos clave que permiten establecer el diagnóstico oportuno y las opciones de tratamiento efectivo para algunos de estos síndromes.


INTRODUCTION The congenital myasthenic syndromes are a heterogeneous group of genetic disorders characterized by an abnormal synaptic transmission in the neuromuscular plate. REPORT We present a two-year-old patient, male, with hypotonia, palpebral ptosis, and proximal symmetric weakness with a neonatal onset that motivated several and prolonged hospitalizations for pneumonia and respiratory failure. From two years of age, the parents noticed that the facial and general weakness worsened in the afternoons and with repeated or prolonged physical activity. The physical examination showed palpebral ptosis, predominantly proximal weakness, and fatigability with sustained muscular effort. The electromyography showed a 27% decrement in the Compound Muscular Action Potential and the case-parents genetic study showed compound heterozygosity with the transmission of two different mutations in the rapsyn gene from both parents. The patient received pyridostigmine with great improvement, achieving optimal performance in school, sports, and daily life activities. CONCLUSIONS Weakness and fatigability with neonatal onset, mainly affecting the muscles with brain stem innervation and the decrement greater than 10 percent in the Compound Muscular Action Potential in the electromyographic studies, should make us suspect in a congenital myasthenic syndrome. We review the literature and key clinical points to establish a timely diagnosis and effective treatment in some of these syndromes.


Assuntos
Humanos , Masculino , Pré-Escolar , Brometo de Piridostigmina/administração & dosagem , Síndromes Miastênicas Congênitas/diagnóstico , Proteínas Musculares/genética , Inibidores da Colinesterase/administração & dosagem , Síndromes Miastênicas Congênitas/genética , Síndromes Miastênicas Congênitas/tratamento farmacológico , Mutação
11.
Clin Neurol Neurosurg ; 158: 53-55, 2017 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-28460343

RESUMO

Limb-girdle myasthenia gravis (LGM) is an uncommon clinical picture related to an antibody-mediated blockage of the neuromuscular junction. We describe a 44-year old man who presented with a proximal limbs' weakness that resembled a myopathic disorder. The repetitive nerve stimulation at 3Hz showing a decremental response suggested myasthenia, that was confirmed by the presence of an increased titer of anti-acetylcholine receptor antibodies (AChRAbs), and of hyperplastic foci at thymus histology. Symptomatic treatment with pyridostigmine was not effective, whereas the patient improved adding Azathioprine. In conclusion, a myopathic-like clinical picture in an adult could be caused by LMG. Thymus pathology, or (rarely) increased AChRAbs could support the diagnosis of LGM.


Assuntos
Miastenia Gravis/diagnóstico , Síndromes Miastênicas Congênitas/diagnóstico , Adulto , Humanos , Masculino , Miastenia Gravis/tratamento farmacológico , Miastenia Gravis/fisiopatologia , Síndromes Miastênicas Congênitas/tratamento farmacológico , Síndromes Miastênicas Congênitas/fisiopatologia
12.
Neuromuscul Disord ; 26(6): 331-4, 2016 06.
Artigo em Inglês | MEDLINE | ID: mdl-27080328

RESUMO

Myasthenia gravis (MG) is a disorder of neuromuscular transmission in which muscle weakness results from an autoantibody mediated depletion of acetylcholine receptors (AChRs) at the neuromuscular junction. Myasthenia gravis occurs spontaneously in dogs and cats, and as in human MG, an autoimmune response against nicotinic AChRs has been demonstrated and autoantibodies against AChRs implicated in the pathogenesis. While both species are affected with MG, there are distinct differences in clinical presentations and frequency of spontaneous remission. Congenital myasthenic syndromes (CMSs) are hereditary disorders of neuromuscular transmission resulting in structural or functional defects of the neuromuscular junction. The clinical presentation and pathogenesis of a CMS in Jack Russell terriers was first described in the 1970's and 1980s and has since been reported in a few other breeds. Mutations have been reported in CHRNE, COLQ and CHAT in canine CMS. A form of COLQ deficient CMS has recently been reported in cats.


Assuntos
Doenças do Gato/genética , Doenças do Gato/fisiopatologia , Doenças do Cão/genética , Doenças do Cão/fisiopatologia , Miastenia Gravis/veterinária , Síndromes Miastênicas Congênitas/veterinária , Animais , Doenças do Gato/tratamento farmacológico , Gatos , Doenças do Cão/tratamento farmacológico , Cães , Miastenia Gravis/tratamento farmacológico , Miastenia Gravis/genética , Miastenia Gravis/fisiopatologia , Síndromes Miastênicas Congênitas/tratamento farmacológico , Síndromes Miastênicas Congênitas/genética , Síndromes Miastênicas Congênitas/fisiopatologia
13.
Pediatr Neurol ; 54: 85-7, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26552645

RESUMO

BACKGROUND: Congenital myasthenic syndromes consist of rare disorders resulting from mutations in genes encoding for presynaptic, synaptic, and postsynaptic proteins that are involved in the signal transmission of the neuromuscular junction. They are characterized by fatigable weakness of the skeletal muscles with symptom onset from birth to early childhood. DOK7 (downstream of tyrosine kinase 7) congenital myasthenic syndrome was previously treated successfully with ephedrine and salbutamol; however, both are unavailable in the United States. METHODS: Case report of a child with muscle weakness. RESULTS: This report describes a boy who presented only with progressive limb-girdle muscle weakness since age 2 years. The muscle biopsy with extensive studies revealed no obvious etiologies. His muscle weakness rapidly worsened, requiring a wheelchair for daily activities. Expanded neuromuscular gene panel promptly led to the diagnosis of DOK7 congenital myasthenic syndrome, and his muscle strength dramatically and persistently improved in four weeks with albuterol treatment, allowing him to walk independently. In a brief literature review, 15 patients (five treated between ages 5 and 17 years) from the Mayo Clinic with DOK7 mutations were also successfully treated with albuterol. CONCLUSION: DOK7 congenital myasthenic syndrome often presents with limb-girdle muscle weakness, which can become progressive without proper treatment. If muscle biopsy reveals no obvious etiology, an expanded neuromuscular gene panel may lead to a specific diagnosis of congenital myasthenic syndrome such as those due to DOK7 mutation. Albuterol is often used to treat bronchial asthma; however, it can also dramatically and persistently improve the muscle strength of DOK7 congenital myasthenic syndrome.


Assuntos
Albuterol/uso terapêutico , Proteínas Musculares/genética , Síndromes Miastênicas Congênitas/tratamento farmacológico , Síndromes Miastênicas Congênitas/genética , Fármacos Neuromusculares/uso terapêutico , Criança , Humanos , Masculino , Síndromes Miastênicas Congênitas/fisiopatologia , Resultado do Tratamento
14.
J Neurosci ; 35(12): 4926-41, 2015 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-25810523

RESUMO

The muscle-specific kinase MuSK is one of the key molecules orchestrating neuromuscular junction (NMJ) formation. MuSK interacts with the Wnt morphogens, through its Frizzled-like domain (cysteine-rich domain [CRD]). Dysfunction of MuSK CRD in patients has been recently associated with the onset of myasthenia, common neuromuscular disorders mainly characterized by fatigable muscle weakness. However, the physiological role of Wnt-MuSK interaction in NMJ formation and function remains to be elucidated. Here, we demonstrate that the CRD deletion of MuSK in mice caused profound defects of both muscle prepatterning, the first step of NMJ formation, and synapse differentiation associated with a drastic deficit in AChR clusters and excessive growth of motor axons that bypass AChR clusters. Moreover, adult MuSKΔCRD mice developed signs of congenital myasthenia, including severe NMJs dismantlement, muscle weakness, and fatigability. We also report, for the first time, the beneficial effects of lithium chloride, a reversible inhibitor of the glycogen synthase kinase-3, that rescued NMJ defects in MuSKΔCRD mice and therefore constitutes a novel therapeutic reagent for the treatment of neuromuscular disorders linked to Wnt-MuSK signaling pathway deficiency. Together, our data reveal that MuSK CRD is critical for NMJ formation and plays an unsuspected role in NMJ maintenance in adulthood.


Assuntos
Glicoproteínas/química , Debilidade Muscular/tratamento farmacológico , Junção Neuromuscular/crescimento & desenvolvimento , Junção Neuromuscular/fisiologia , Receptores Proteína Tirosina Quinases/química , Receptores Proteína Tirosina Quinases/fisiologia , Acetilcolinesterase/metabolismo , Animais , Animais Recém-Nascidos , Fadiga/genética , Fadiga/fisiopatologia , Feminino , Força da Mão/fisiologia , Peptídeos e Proteínas de Sinalização Intracelular , Cloreto de Lítio/farmacologia , Cloreto de Lítio/uso terapêutico , Masculino , Camundongos , Camundongos Transgênicos , Neurônios Motores/efeitos dos fármacos , Neurônios Motores/fisiologia , Debilidade Muscular/genética , Debilidade Muscular/fisiopatologia , Mutação , Síndromes Miastênicas Congênitas/tratamento farmacológico , Síndromes Miastênicas Congênitas/genética , Síndromes Miastênicas Congênitas/fisiopatologia , Junção Neuromuscular/efeitos dos fármacos , Junção Neuromuscular/ultraestrutura , Gravidez , Cultura Primária de Células , Receptores Proteína Tirosina Quinases/genética , Receptores Colinérgicos/metabolismo
15.
Cochrane Database Syst Rev ; (12): CD010028, 2014 Dec 17.
Artigo em Inglês | MEDLINE | ID: mdl-25515947

RESUMO

BACKGROUND: Myasthenia is a condition in which neuromuscular transmission is affected by antibodies against neuromuscular junction components (autoimmune myasthenia gravis, MG; and neonatal myasthenia gravis, NMG) or by defects in genes for neuromuscular junction proteins (congenital myasthenic syndromes, CMSs). Clinically, some individuals seem to benefit from treatment with ephedrine, but its effects and adverse effects have not been systematically evaluated. OBJECTIVES: To assess the effects and adverse effects of ephedrine in people with autoimmune MG, transient neonatal MG, and the congenital myasthenic syndromes. SEARCH METHODS: On 17 November 2014, we searched the Cochrane Neuromuscular Disease Group Specialized Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE and EMBASE. We also searched reference lists of articles, conference proceedings of relevant conferences, and prospective trial registers. In addition, we contacted manufacturers and researchers in the field. SELECTION CRITERIA: We considered randomised controlled trials (RCTs) and quasi-RCTs comparing ephedrine as a single or add-on treatment with any other active treatment, placebo, or no treatment in adults or children with autoimmune MG, NMG, or CMSs. DATA COLLECTION AND ANALYSIS: Two review authors independently assessed study design and quality, and extracted data. We contacted study authors for additional information. We collected information on adverse effects from included articles, and contacted authors. MAIN RESULTS: We found no RCTs or quasi-RCTs, and therefore could not establish the effect of ephedrine on MG, NMG and CMSs. We describe the results of 53 non-randomised studies narratively in the Discussion section, including observations of endurance, muscle strength and quality of life. Effects may differ depending on the type of myasthenia. Thirty-seven studies were in participants with CMS, five in participants with MG, and in 11 the precise form of myasthenia was unknown. We found no studies for NMG. Reported adverse effects included tachycardia, sleep disturbances, nervousness, and withdrawal symptoms. AUTHORS' CONCLUSIONS: There was no evidence available from RCTs or quasi-RCTs, but some observations from non-randomised studies are available. There is a need for more evidence from suitable forms of prospective RCTs, such as series of n-of-one RCTs, that use appropriate and validated outcome measures.


Assuntos
Adrenérgicos/uso terapêutico , Efedrina/uso terapêutico , Miastenia Gravis/tratamento farmacológico , Adulto , Criança , Inibidores da Colinesterase/uso terapêutico , Humanos , Recém-Nascido , Miastenia Gravis Neonatal/tratamento farmacológico , Síndromes Miastênicas Congênitas/tratamento farmacológico
16.
BMJ Case Rep ; 20142014 Oct 27.
Artigo em Inglês | MEDLINE | ID: mdl-25349186

RESUMO

Two siblings, an 11-year-old boy and a 7-year-old girl presented with bilateral symmetrical ptosis and limited eye movements. Having already been reviewed on a number of occasions by a variety of specialists in multiple hospital settings a diagnosis of their ocular motility disorder had remained elusive. We describe their cases, outline the differential diagnosis and review the investigations performed which were influential in finally making a diagnosis.


Assuntos
Blefaroptose/complicações , Síndromes Miastênicas Congênitas/complicações , Síndromes Miastênicas Congênitas/diagnóstico , Transtornos da Motilidade Ocular/complicações , Encefalopatias/complicações , Criança , Inibidores da Colinesterase/uso terapêutico , Cistos/complicações , Diagnóstico Diferencial , Feminino , Humanos , Imageamento por Ressonância Magnética/métodos , Masculino , Síndromes Miastênicas Congênitas/tratamento farmacológico , Glândula Pineal/patologia , Brometo de Piridostigmina/uso terapêutico
17.
J Mol Neurosci ; 53(3): 359-61, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24234034

RESUMO

Acetylcholinesterase (AChE) at the neuromuscular junction (NMJ) is anchored to the synaptic basal lamina via a triple helical collagen Q (ColQ) in the form of asymmetric AChE (AChE/ColQ). We exploited the proprietary NMJ-targeting signals of ColQ to treat congenital myasthenia and to explore the mechanisms of autoimmune myasthenia gravis (MG). Mutations in COLQ cause congenital endplate AChE deficiency (CEAD). First, a single intravenous administration of adeno-associated virus serotype 8 (AAV8)-COLQ to Colq−/− mice normalized motor functions, synaptic transmission, and partly the NMJ ultrastructure. Additionally, injection of purified recombinant AChE/ColQ protein complex into gluteus maximus accumulated AChE in non-injected forelimbs. Second, MuSK antibody-positive MG accounts for 5-15 % of MG. In vitro overlay of AChE/ColQ to muscle sections of Colq−/− mice, as well as in vitro plate-binding of MuSK to ColQ, revealed thatMuSK-IgG blocks binding of ColQ to MuSK in a dose-dependent manner. Passive transfer of MuSK-IgG to wild-type mice markedly reduced the size and intensity of ColQ signals at NMJs. MuSK-IgG thus interferes with binding of ColQ to MuSK. Elucidation of molecular mechanisms of specific binding of ColQ to NMJ enabled us to ameliorate devastating myasthenic symptoms of Colq−/− mice and also to reveal underlying mechanisms of anti-MuSK-MG.


Assuntos
Colágeno/metabolismo , Miastenia Gravis Autoimune Experimental/metabolismo , Síndromes Miastênicas Congênitas/tratamento farmacológico , Receptores Proteína Tirosina Quinases/imunologia , Receptores Colinérgicos/imunologia , Acetilcolinesterase/metabolismo , Animais , Anticorpos/farmacologia , Anticorpos/uso terapêutico , Colágeno/genética , Humanos , Placa Motora/efeitos dos fármacos , Placa Motora/metabolismo , Síndromes Miastênicas Congênitas/metabolismo , Receptores Proteína Tirosina Quinases/metabolismo , Receptores Colinérgicos/metabolismo
18.
Clin Genet ; 85(2): 166-71, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-23488891

RESUMO

The term 'limb-girdle myasthenia' (LGM) was first used to describe three siblings with proximal limb weakness without oculobulbar involvement, but with EMG decrement and responsiveness to anticholinesterase medication. We report here that exome sequencing in the proband of this family revealed several sequence variations in genes linked to proximal limb weakness. However, the only mutations that cosegregated with disease were an intronic IVS7-8A>G mutation and the previously reported 3'-UTR c.*22C>A mutation in GFPT1, a gene linked to LGM. A minigene assay showed that IVS7-8A>G activates an alternative splice acceptor that results in retention of the last seven nucleotides of intron 7 and a frameshift leading to a termination codon 13 nucleotides downstream from the new splice site. An anconeus muscle biopsy revealed mild reduction of the axon terminal size and postsynaptic fold simplification. The amplitudes of miniature endplate potentials and quantal release were also diminished. The DNA of the mildly affected father of the proband showed only the intronic mutation along with sequence variations in other genes potentially relevant to LGM. Thus, this study performed in the family originally described with LGM showed two GFPT1 untranslated mutations, which may cause disease by reducing GFPT1 expression and ultimately impairing protein glycosylation.


Assuntos
Exoma/genética , Glutamina-Frutose-6-Fosfato Transaminase (Isomerizante)/genética , Miastenia Gravis/genética , Síndromes Miastênicas Congênitas/genética , 4-Aminopiridina/análogos & derivados , 4-Aminopiridina/uso terapêutico , Idoso , Amifampridina , Sequência de Bases , Análise Mutacional de DNA , Eletromiografia , Feminino , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Dados de Sequência Molecular , Miastenia Gravis/tratamento farmacológico , Miastenia Gravis/patologia , Síndromes Miastênicas Congênitas/tratamento farmacológico , Síndromes Miastênicas Congênitas/patologia , Neostigmina/uso terapêutico , Junção Neuromuscular/ultraestrutura , Linhagem , Reação em Cadeia da Polimerase Via Transcriptase Reversa
19.
Acta Myol ; 29(2): 343-50, 2010 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-21314017

RESUMO

A combination of electrophysiological and genetic studies has resulted in the identification of several skeletal muscle disorders to be caused by pathologically functioning ion channels and has led to the term channelopathies. Typical hereditary muscle channelopa thies are congenital myasthenic syndromes, non-dystrophic myotonias, periodic paralyses, malignant hyperthermia, and central core disease. Most muscle channelopathies are commonly considered to be benign diseases. However, life-threatening weakness episodes or progressive permanent weakness may make these diseases severe, particularly the periodic paralyses (PP). Even in the typical PP forms characterized by episodic occurrence of weakness, up to 60% of the patients suffer from permanent weakness and myopathy with age. In addition, some PP patients present with a predominant progressive muscle weakness phenotype. The weakness can be explained by strongly depolarized fibers that take up sodium and water and that are electrically inexcitable. Drugs that repolarize the fiber membrane can restore muscle strength and may prevent progression.


Assuntos
Canalopatias/tratamento farmacológico , Canalopatias/genética , Tratamento Farmacológico/tendências , Anestésicos Locais/uso terapêutico , Antiarrítmicos/uso terapêutico , Diuréticos/uso terapêutico , Humanos , Síndromes Miastênicas Congênitas/tratamento farmacológico , Síndromes Miastênicas Congênitas/genética , Miotonia/tratamento farmacológico , Miotonia/genética , Paralisias Periódicas Familiares/tratamento farmacológico , Paralisias Periódicas Familiares/genética
20.
No To Hattatsu ; 41(1): 37-42, 2009 Jan.
Artigo em Japonês | MEDLINE | ID: mdl-19172815

RESUMO

Congenital myasthenic syndromes (CMS) are rare heterogeneous disorders of neurotransmission caused by genetic defects of neuromuscular junction molecules. While CMS patients have been reported worldwide, in Japan there have been only a few descriptions of adult CMS patients with acetylcholinesterase (AChE) deficiency and slow channel syndrome. Herein, we report a Japanese CMS patient with acetylcholine receptor (AChR) deficiency, diagnosed during childhood, and our treatment approach to the patient. This 13-year-old Japanese boy had had severe myasthenic symptoms since infancy. Ptosis, his first symptom, appeared at 5 months and nasal voice was recognized at 2 years of age. AchR and anti-muscle-specific tyrosine kinase (Musk) antibody remained negative. A positive tensilon test and decremental response on electromyogram supported the diagnosis of sero-negative myasthenia gravis. Despite thymectomy and strong immunosuppressive therapy including steroid pulse and FK 506, he gradually deteriorated and became wheelchair bound. Genetic analyses for AchR, Rapsyn, Musk and AChE were negative. At age 11 years, a muscle biopsy was performed in the deltoid muscle for neuromuscular junction sampling. Electron microscopic and confocal microscopic analysis of endplates showed almost complete loss of AChR and the diagnosis of CMS with AChR deficiency was confirmed. All immunosuppressive therapies were discontinued. Instead, we started Ubretide and 3,4-diaminopyridine (DAP) after obtaining informed consent. Although not approved in Japan for this use, 3,4-DAP is reportedly effective in refractory cases of CMS. The patient experienced no side effects. Despite all of the objective data were improving, his subjective symptoms and ADL remained poor. There are still many challenges in the treatment of the patient.


Assuntos
4-Aminopiridina/análogos & derivados , Síndromes Miastênicas Congênitas/tratamento farmacológico , Síndromes Miastênicas Congênitas/etiologia , Compostos de Piridínio/uso terapêutico , Receptores Colinérgicos/deficiência , 4-Aminopiridina/uso terapêutico , Adolescente , Amifampridina , Diagnóstico Diferencial , Humanos , Masculino , Síndromes Miastênicas Congênitas/diagnóstico , Síndromes Miastênicas Congênitas/patologia , Junção Neuromuscular/patologia , Resultado do Tratamento
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