RESUMO
Charcot-Marie-Tooth disease (CMT) is a group of clinically and genetically heterogeneous neuropathies classically divided into demyelinating (CMT1) and axonal forms (CMT2). The most common demyelinating form is CMT1A, due to a duplication in the gene encoding the peripheral myelin protein 22 (PMP22). Less frequently, mutations in the myelin protein zero gene (MPZ/P0) account for demyelinating CMT1B. Herein, we report a patient presenting with an isolated hyperCKemia in whom electrophysiological and pathological findings revealed a demyelinating and axonal neuropathy. Sequencing of the MPZ gene revealed a 306delA at codon 102 in the proband and in two relatives. This mutation has been already described in association with paucisymptomatic CMT without hyperCKemia.
Assuntos
Doença de Charcot-Marie-Tooth/genética , Creatina Quinase/sangue , Mutação/fisiologia , Proteína P0 da Mielina/genética , Potenciais de Ação/fisiologia , Adulto , Axônios/patologia , Biópsia , Doença de Charcot-Marie-Tooth/diagnóstico , Doença de Charcot-Marie-Tooth/patologia , Códon/genética , Diagnóstico , Eletromiografia , Família , Testes Genéticos , Humanos , Masculino , Neurônios Motores/fisiologia , Condução Nervosa/fisiologia , Exame Neurológico , Nervos Periféricos/fisiopatologia , Células Receptoras Sensoriais/fisiologiaRESUMO
The aim of this work was to investigate in muscle the role of apoptosis and of oxidative stress in mitochondrial disorders with dysfunction of respiratory chain. In patients with cytochrome c oxidase deficiency (COX) we found a variable number of myofibers with apoptotic nuclei that matched with the level of enzymatic reduction and roughly correlated with muscle weakness. In parallel, a positive immunostaining for apoptosis-related proteins and Mn and Cu/Zn superoxide dismutase (SOD) were mostly localized in COX-negative fibers. Moreover, glutathione peroxidase activity was increased in muscles with high number of SOD-positive myofibers and prominent apoptotic features. No signs of apoptosis were observed in patients with deficiencies of complexes I and II and without muscle weakness. These data suggest that apoptosis along with increased ROS production, revealed by anti-oxidant enzymes overexpression, may play an important role in the pathophysiology of mitochondrial diseases associated with COX deficiency.
Assuntos
Apoptose/fisiologia , Deficiência de Citocromo-c Oxidase , Encefalomiopatias Mitocondriais/enzimologia , Encefalomiopatias Mitocondriais/patologia , Adulto , Idoso , Biópsia , Caspase 1/análise , Caspase 3 , Caspases/análise , Criança , Pré-Escolar , Fragmentação do DNA , Complexo IV da Cadeia de Transporte de Elétrons/análise , Feminino , Glutationa Peroxidase/metabolismo , Humanos , Marcação In Situ das Extremidades Cortadas , Lactente , Recém-Nascido , Masculino , Microscopia Eletrônica , Pessoa de Meia-Idade , Fibras Musculares Esqueléticas/enzimologia , Fibras Musculares Esqueléticas/patologia , Fibras Musculares Esqueléticas/ultraestrutura , Músculo Esquelético/enzimologia , Músculo Esquelético/patologia , Espécies Reativas de Oxigênio/metabolismo , Superóxido Dismutase/análise , Receptor fas/análiseRESUMO
We performed morphological, biochemical, and genetic studies, including single-fiber PCR (sf PCR), on muscle biopsies obtained from a mother and daughter with MELAS syndrome due to the A3243G transition of mitochondrial DNA (mtDNA). The severity of muscle involvement appeared quite distinct, in spite of the fact that both patients segregated similar mutant mtDNA levels on total muscle DNA. The daughter did not show any clinical muscle involvement: muscle biopsy revealed many ragged red fibers (RRFs) mostly positive for cytochrome-c oxidase (COX) activity. In contrast, her mother had developed a generalized myopathy without progressive external ophthalmoplegia (PEO), morphologically characterized by many COX-negative RRFs. Single-muscle fiber PCR demonstrated in both patients significantly higher percentages of wild-type mtDNA in normal fibers (daughter: 23.25 +/- 15.22; mother: 43.13 +/- 26.11) than in COX-positive RRFs (daughter: 11.25 +/- 5.22, P < 0.005; mother: 9.12 +/- 5.9, P < 0.001) and in COX-negative RRFs (daughter: 8.9 +/- 4.2, P < 0.001 mother: 4.8 +/- 2.8, P < 0.001). Wild-type mtDNA levels resulted higher also in COX-positive vs. COX-negative RRFs (daughter: P < 0.05; mother: P < 0.001). Our data confirm a direct correlation between A3243G levels and impairment of COX function at the single-muscle fiber level. Moreover, the evidence of a clinical myopathy in the patient with higher amounts of COX-negative RRFs bolsters the concept that a differential distribution of mutant mtDNAs at the cellular level may have effects on the clinical involvement of individual tissues. However, the occurrence of a similar morphological and biochemical muscle phenotype also in PEO(3243) patients suggests that other genetic factors involved in the interaction between mitochondrial and nuclear DNA, rather than the stochastic distribution of mtDNA genomes during embryogenesis, are primarily implicated in determining the various clinical expressions of the A3243G of mtDNA.
Assuntos
DNA Mitocondrial , Síndrome MELAS/genética , Programas de Rastreamento/métodos , Doenças Musculares/genética , Reação em Cadeia da Polimerase/métodos , Adolescente , Demência/genética , Complexo IV da Cadeia de Transporte de Elétrons/biossíntese , Saúde da Família , Feminino , Genótipo , Humanos , Pessoa de Meia-Idade , Fibras Musculares Esqueléticas/enzimologia , Fibras Musculares Esqueléticas/patologia , Músculos/metabolismo , Fenótipo , Mutação Puntual , Polimorfismo de Fragmento de Restrição , Convulsões/genética , Succinato Desidrogenase/biossíntese , Distribuição TecidualRESUMO
We describe clinical, morphological and biochemical findings of a patient with reducing body myopathy (RBM). This 15-year-old patient was affected by severe limb-girdle progressive myopathy with asymmetric distribution. Muscle biopsy showed many fibers with cytoplasmic polymorphic masses, which stained dark purple with modified Gomori's trichrome, associated with proliferation of cytoplasmic bodies. Cytoplasmic polymorphic masses showed marked reducing activity with menadione-nitro blue tetrazolium reaction. Ultrastructurally, there was great amount of highly electron-dense tubular-filamentous structures of 16-17 nm in diameter. Immunohistochemistry showed that many fibers were positive for desmin. Sodium dodecyl sulfate-electrophoresis disclosed an increase in two bands of approximately 53 and 70 kDa, and Western blot demonstrated that the 53-kDa band was desmin. It was not possible to characterize the 70-kDa protein further.
Assuntos
Desmina/metabolismo , Músculos/patologia , Doenças Musculares/patologia , Adolescente , Desmina/análise , Eletroforese em Gel Bidimensional , Eletroforese em Gel de Poliacrilamida , Feminino , Fibrose , Imunofluorescência , Humanos , Microscopia Eletrônica , Músculos/ultraestrutura , Doenças Musculares/metabolismo , Miofibrilas/patologia , Miofibrilas/ultraestruturaRESUMO
We report a family with McArdle's disease with several affected individuals in two generations. This unusual pedigree for an autosomal recessive disease is explained by the existence of manifesting heterozygotes in the maternal line. The presence of symptoms in heterozygotes seems to be due to a decrease in myophosphorylase activity below a critical threshold, ranging between 30% and 45% of normal mean value. The occurrence of several manifesting heterozygotes in the maternal line only can be explained by compound heterozygosity of a defective allele and a pseudodeficient allele for myophosphorylase, or by a genetic factor which regulates the phenotypic expression of the gene.
Assuntos
Doença de Depósito de Glicogênio Tipo V/genética , Heterozigoto , Adolescente , Adulto , Densitometria , Eletroforese em Gel de Poliacrilamida , Feminino , Glicogênio/metabolismo , Doença de Depósito de Glicogênio Tipo V/metabolismo , Doença de Depósito de Glicogênio Tipo V/patologia , Humanos , Itália , Masculino , Músculos/enzimologia , Doenças Musculares/fisiopatologia , Dor/fisiopatologia , Fenótipo , Fosforilase a/deficiência , Fosforilase a/metabolismoRESUMO
A sporadic case (female, aged 14 years) is reported who was affected by myopathy, restrictive cardiomyopathy and sensory motor polyneuropathy. A muscle biopsy showed accumulation of osmiophilic granular and filamentous material on electron microscopy, which stained positively in immunofluorescence for desmin. Increased desmin phosphorylated isoforms have been demonstrated by one- and two-dimensional electrophoresis. Sural nerve biopsy showed a peripheral neuropathy with giant axons, filled with closely packed neurofilaments. Clinical and morphological aspects of this new disease entity are discussed with regards to the classical form of giant axonal neuropathy and to other conditions of peripheral neuropathy with giant axons.