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- Casar-Borota, Olivera, et al.
(författare)
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A novel dynamin-2 gene mutation associated with a late-onset centronuclear myopathy with unusual clinical presentation and necklace fibres
- 2012
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Ingår i: Neuromuscular Disorders. - Oxford : Elsevier BV. - 0960-8966 .- 1873-2364. ; 22:9-10, s. 843-843
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Nuclear centralisation and internalisation, sarcoplasmic radiating strands and type 1 muscle fibre predominance and hypotrophy are morphologic features of centronuclear myopathy (CNM) related to dynamin-2 (DNM2) gene defects, whereas necklace fibres characterise late-onset myopathy associated with myotubularin-1 (MTM1) gene defects. We report a 40-year-old woman with 1-year history of pain and paresthesia in the left shoulder and arm that was clinically interpreted as brachial plexus neuritis. Electromyography revealed both myopathic and neuropathic abnormalities, and because of the myopathic changes a muscle biopsy was performed. The typical morphologic features of dynamin-2 CNM with additional numerous necklace fibres were found in the muscle biopsy. Sequencing of the DNM2 and MTM1 genes revealed a not previously described heterozygous missense mutation in exon 18 of DNM2 leading to replacement of highly conserved Proline in position 647 by Arginine. The muscle symptoms have not progressed during the two-year follow-up, but the patient has developed bilateral subtle lens opacities. Necklace fibres were originally described as fibres that had usually a small diameter and internalized nuclei aligned in a basophilic ring at a few micrometers beneath the sarcolemma. They were described in association with myopathies caused by MTM1 mutations, and similar but not identical fibres have also been reported in a case of DNM2 associated CNM. Our findings support the concept that necklace fibres are not specific but indicate common pathogenic mechanisms in DNM2 and MTM1 associated CNM. This case report expands the clinical, morphological and molecular genetic variability of DNM2 associated CNM.
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| 2. |
- Hedberg, C., et al.
(författare)
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Hereditary myopathy with early respiratory failure associated with a mutation in A-band titin
- 2012
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Ingår i: Neuromuscular Disorders. - : Elsevier BV. - 0960-8966 .- 1873-2364. ; 22:9-10, s. 873-873
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Hereditary myopathy with early respiratory failure (HMERF) and extensive myofibrillar lesions have been described in sporadic and familial cases and linked to various chromosomal regions. We describe the clinical manifestations, muscle histopathology and genetics in eight individuals from three apparently unrelated families with clinical and pathological features of HMERF. All patients had muscle weakness in the pelvic girdle, neck flexors, respiratory and trunk muscles, and the majority had prominent calf hypertrophy. Examination of pulmonary function showed decreased vital capacity. No signs of cardiac muscle involvement were found. Muscle histopathological features included marked muscle fibre size variation, fibre splitting, numerous internal nuclei and fatty infiltration. Frequent groups of fibres showed eosinophilic inclusions and deposits. At the ultrastructural level there were extensive myofibrillar lesions with marked Z-disc alterations. Whole exome sequencing in four individuals from one family revealed a missense mutation, g.274375, T>C; p.Cys30071Arg, in the titin gene, TTN. The mutation, which changes a highly conserved residue in the myosin binding A-band titin, was demonstrated to segregate with the disease in all three families. High density single nucleotide polymorphism arrays covering the entire genome demonstrated sharing of a 699 Mb haplotype, located in chromosome region 2q31 including TTN, indicating common ancestry of this novel and first disease-causing mutation in A-band titin associated with HMERF.
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| 7. |
- Tajsharghi, Homa, et al.
(författare)
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Myopathies associated with β-tropomyosin mutations
- 2012
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Ingår i: Neuromuscular Disorders. - : Elsevier. - 0960-8966 .- 1873-2364. ; 22:11, s. 923-933
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Forskningsöversikt (refereegranskat)abstract
- Mutations in TPM2, encoding β-tropomyosin, have recently been found to cause a range of muscle disorders. We review the clinical and morphological expression of the previously reported mutations illustrating the heterogeneity of β-tropomyosin-associated diseases and describe an additional case with a novel mutation. The manifestations of mutations in TPM2 include non-specific congenital myopathy with type 1 fibre predominance, nemaline myopathy, cap disease and distal arthrogryposis. In addition, Escobar syndrome with nemaline myopathy is a manifestation of homozygous truncating β-tropomyosin mutation. Cap disease appears to be the most common morphological manifestation. A coarse intermyofibrillar network and jagged Z lines are additional frequent changes. The dominant β-tropomyosin mutations manifest either as congenital myopathy or distal arthrogryposis. The various congenital myopathies are usually associated with moderate muscle weakness and no congenital joint contractures. The distal arthrogryposis syndromes associated with TPM2 mutations include the less severe forms, with congenital contractures mainly of the hands and feet and mild or no muscle weakness. The dominant TPM2 mutations include amino acid deletions/insertions and missense mutations. There is no clear relation between the type of mutations or the localisation of the mutated residue in the β-tropomyosin molecule and the clinical and morphological phenotype.
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