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- Ávila-Polo, R., et al.
(författare)
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Loss of Sarcomeric Scaffolding as a Common Baseline Histopathologic Lesion in Titin-Related Myopathies
- 2018
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Ingår i: Journal of Neuropathology and Experimental Neurology. - : Oxford University Press (OUP). - 1554-6578 .- 0022-3069. ; 77:12, s. 1101-1114
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Tidskriftsartikel (refereegranskat)abstract
- Titin-related myopathies are heterogeneous clinical conditions associated with mutations in TTN. To define their histopathologic boundaries and try to overcome the difficulty in assessing the pathogenic role of TTN variants, we performed a thorough morphological skeletal muscle analysis including light and electron microscopy in 23 patients with different clinical phenotypes presenting pathogenic autosomal dominant or autosomal recessive (AR) mutations located in different TTN domains. We identified a consistent pattern characterized by diverse defects in oxidative staining with prominent nuclear internalization in congenital phenotypes (AR-CM) (n = 10), ± necrotic/regenerative fibers, associated with endomysial fibrosis and rimmed vacuoles (RVs) in AR early-onset Emery-Dreifuss-like (AR-ED) (n = 4) and AR adult-onset distal myopathies (n = 4), and cytoplasmic bodies (CBs) as predominant finding in hereditary myopathy with early respiratory failure (HMERF) patients (n = 5). Ultrastructurally, the most significant abnormalities, particularly in AR-CM, were multiple narrow core lesions and/or clear small areas of disorganizations affecting one or a few sarcomeres with M-band and sometimes A-band disruption and loss of thick filaments. CBs were noted in some AR-CM and associated with RVs in HMERF and some AR-ED cases. As a whole, we described recognizable histopathological patterns and structural alterations that could point toward considering the pathogenicity of TTN mutations.
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| 2. |
- Lange, S, et al.
(författare)
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The kinase domain of titin controls muscle gene expression and protein turnover
- 2005
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Ingår i: Science (New York, N.Y.). - : American Association for the Advancement of Science (AAAS). - 1095-9203 .- 0036-8075. ; 308:5728, s. 1599-1603
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Tidskriftsartikel (refereegranskat)abstract
- The giant sarcomeric protein titin contains a protein kinase domain (TK) ideally positioned to sense mechanical load. We identified a signaling complex where TK interacts with the zinc-finger protein nbr1 through a mechanically inducible conformation. Nbr1 targets the ubiquitin-associated p62/SQSTM1 to sarcomeres, and p62 in turn interacts with MuRF2, a muscle-specific RING-B-box E3 ligase and ligand of the transactivation domain of the serum response transcription factor (SRF). Nuclear translocation of MuRF2 was induced by mechanical inactivity and caused reduction of nuclear SRF and repression of transcription. A human mutation in the titin protein kinase domain causes hereditary muscle disease by disrupting this pathway.
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| 3. |
- Schiava, M., et al.
(författare)
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Genotype-phenotype correlations in valosin-containing protein disease: a retrospective muticentre study
- 2022
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Ingår i: Journal of Neurology Neurosurgery and Psychiatry. - : BMJ. - 0022-3050 .- 1468-330X. ; 93:10, s. 1099-1111
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Tidskriftsartikel (refereegranskat)abstract
- Background Valosin-containing protein (VCP) disease, caused by mutations in the VCP gene, results in myopathy, Paget's disease of bone (PBD) and frontotemporal dementia (FTD). Natural history and genotype-phenotype correlation data are limited. This study characterises patients with mutations in VCP gene and investigates genotype-phenotype correlations. Methods Descriptive retrospective international study collecting clinical and genetic data of patients with mutations in the VCP gene. Results Two hundred and fifty-five patients (70.0% males) were included in the study. Mean age was 56.8 +/- 9.6 years and mean age of onset 45.6 +/- 9.3 years. Mean diagnostic delay was 7.7 +/- 6 years. Symmetric lower limb weakness was reported in 50% at onset progressing to generalised muscle weakness. Other common symptoms were ventilatory insufficiency 40.3%, PDB 28.2%, dysautonomia 21.4% and FTD 14.3%. Fifty-seven genetic variants were identified, 18 of these no previously reported. c.464G>A (p.Arg155His) was the most frequent variant, identified in the 28%. Full time wheelchair users accounted for 19.1% with a median time from disease onset to been wheelchair user of 8.5 years. Variant c.463C>T (p.Arg155Cys) showed an earlier onset (37.8 +/- 7.6 year) and a higher frequency of axial and upper limb weakness, scapular winging and cognitive impairment. Forced vital capacity (FVC) below 50% was as risk factor for being full-time wheelchair user, while FVC Conclusion This study expands the knowledge on the phenotypic presentation, natural history, genotype-phenotype correlations and risk factors for disease progression of VCP disease and is useful to improve the care provided to patient with this complex disease.
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| 5. |
- 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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