| 1. |
- Arkblad, Eva L, et al.
(författare)
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Multiplex ligation-dependent probe amplification improves diagnostics in spinal muscular atrophy
- 2006
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Ingår i: Neuromuscular disorders : NMD. - : Elsevier BV. - 0960-8966 .- 1873-2364. ; 16:12, s. 830-8
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Tidskriftsartikel (refereegranskat)abstract
- Spinal muscular atrophy (SMA) is an autosomal recessive disease caused by decreased levels of survival motor neuron protein (SMN). In the majority of cases, this decrease is due to absence of the SMN1 gene. Multiplex ligation-dependent probe amplification (MLPA) is a modern quantitative molecular method. Applied in SMA cases, it improves diagnostics by simultaneously identifying the number of copies of several target sequences in the SMN1 gene and in nearby genes. Using MLPA in clinical diagnostics, we have identified a previously unreported, partial deletion of SMN1 (exons 1-6) in two apparently unrelated Swedish families. This mutation would not have been detected by conventional diagnostic methods. This paper illustrates the broad clinical and genetic spectrum of SMA and includes reports of MLPA results and clinical descriptions of a patient with homozygous absence of SMN1 and only one SMN2 (prenatal onset SMA type 1), an asymptomatic woman with five SMN2 (lacking SMN1) and representative patients with SMA types 1, 2 and 3.
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| 2. |
- Kimber, Eva, 1951, et al.
(författare)
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A mutation in the fast skeletal muscle troponin I gene causes myopathy and distal arthrogryposis
- 2006
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Ingår i: Neurology. - : Ovid Technologies (Wolters Kluwer Health). - 1526-632X .- 0028-3878. ; 67:4, s. 597-601
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To describe a three-generation family with distal arthrogryposis associated with myopathy and caused by a mutation in the gene encoding for sarcomeric thin filament protein troponin I, TNNI2. METHODS: The authors performed clinical investigations and reviewed medical records. Muscle biopsy specimens were obtained for morphologic analysis. Genomic DNA was extracted from blood and analyzed for mutations in TNNI2. RESULTS: The five affected individuals had predominantly distal congenital joint contractures, mild facial involvement (mild micrognathia, narrow palpebral fissures), and no detectable muscle weakness. The four affected adults had slightly increased levels of creatine kinase in blood, and muscle biopsy specimens showed findings of myopathy with changes restricted to type 2 fibers. These included variability of muscle fiber size, internalized nuclei, and increased interstitial connective tissue. Analysis of TNNI2 encoding the troponin I isoform expressed in type 2 muscle fibers disclosed a heterozygous three-base in-frame deletion, 2,918-2,920del, skipping the highly conserved lysine at position 176. The mutation was present in all 5 affected individuals but was not identified in any of the 11 unaffected family members. CONCLUSION: Distal arthrogryposis type 1 is genetically heterogeneous, and myopathy due to sarcomeric protein dysfunction may be one underlying cause of the disease.
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| 3. |
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| 4. |
- Kimber, Eva, 1951-, et al.
(författare)
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Distal arthrogryposis : clinical and genetic findings
- 2012
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Ingår i: Acta Paediatrica. - : John Wiley & Sons. - 0803-5253 .- 1651-2227. ; 101:8, s. 877-887
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Tidskriftsartikel (refereegranskat)abstract
- AIM: Distal arthrogryposis is characterized by congenital contractures predominantly in hands and feet. Mutations in sarcomeric protein genes are involved in several types of distal arthrogryposis. Our aim is to describe clinical and molecular genetic findings in individuals with distal arthrogryposis and evaluate the genotype-phenotype correlation.METHOD: We investigated 39 patients from 21 families. Clinical history, including neonatal findings, joint involvement and motor function, was documented. Clinical examination was performed including evaluation of muscle strength. Molecular genetic investigations were carried out in 19 index cases. Muscle biopsies from 17 patients were analysed.RESULTS: A pathogenic mutation was found in six families with 19 affected family members with autosomal dominant inheritance and in one child with sporadic occurrence. In three families and in one child with sporadic form, the identified mutation was de novo. Muscle weakness was found in 17 patients. Ambulation was affected in four patients and hand function in 28. Fourteen patients reported pain related to muscle and joint affection.CONCLUSION: The clinical findings were highly variable between families and also within families. Mutations in the same gene were found in different syndromes suggesting varying clinical penetrance and expression, and different gene mutations were found in the same clinical syndrome demonstrating genetic heterogeneity.
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| 5. |
- Kroksmark, Anna-Karin, et al.
(författare)
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Muscle involvement and motor function in amyoplasia
- 2006
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Ingår i: Am J Med Genet A. - : Wiley. - 1552-4825 .- 1552-4833. ; 140:16, s. 1757-67
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Tidskriftsartikel (refereegranskat)abstract
- The most common form of arthrogryposis multiplex congenita (AMC) is amyoplasia. Diagnostic criteria are highly specific, with decreased muscle mass, typical contractures and limb positioning at birth. Intellectual development is normal. The aims of this study were to investigate how muscle strength and contractures affect motor function in amyoplasia, and to relate current functional status to joint positions at birth. Medical records were reviewed and a clinical examination was performed, with investigation of muscle strength, range of motion, and motor function. Thirty-five patients with amyoplasia participated and were divided into three functional groups: 11 community ambulators, 11 household ambulators, and 7 non-ambulators. Six children less than 2 years old were not categorized. Community ambulators had the best muscle strength and none had knee flexion contractures extending 20 degrees. Household ambulators had severe contractures in the lower limbs, but good muscle strength in the upper limbs. Non-ambulators had most severe contractures and most severely reduced muscle strength. Most of the non-ambulators were born with hips in severe abduction, flexion and external rotation. Good and very good correlations were found between muscle strength and motor function, and only moderate correlations between range of motion and motor function. We conclude that more attention should be paid to developing muscle strength, with early stimulation of active movement, and that periods of immobilization should be minimized. Further, ultrasound or MRI of muscle tissue in the newborn period would be useful to evaluate prerequisites for future development of muscle strength and thereby anticipate response to therapy.
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| 6. |
- Ochala, Julien, et al.
(författare)
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Effects of a R133W beta-tropomyosin mutation on regulation of muscle contraction in single human muscle fibres
- 2007
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Ingår i: Journal of Physiology. - : Wiley. - 0022-3751 .- 1469-7793. ; 581:Pt 3, s. 1283-92
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Tidskriftsartikel (refereegranskat)abstract
- A novel R133W β-tropomyosin (β-Tm) mutation, associated with muscle weakness and distal limb deformities, has recently been identified in a woman and her daughter. The muscle weakness was not accompanied by progressive muscle wasting or histopathological abnormalities in tibialis anterior muscle biopsy specimens. The aim of the present study was to explore the mechanisms underlying the impaired muscle function in patients with the β-Tm mutation. Maximum force normalized to fibre cross-sectional area (specific force, SF), maximum velocity of unloaded shortening (V0), apparent rate constant of force redevelopment (ktr) and force–pCa relationship were evaluated in single chemically skinned muscle fibres from the two patients carrying the β-Tm mutation and from healthy control subjects. Significant differences in regulation of muscle contraction were observed in the type I fibres: a lower SF (P < 0.05) and ktr (P < 0.01), and a faster V0 (P < 0.05). The force–pCa relationship did not differ between patient and control fibres, indicating an unaltered Ca2+ activation of contractile proteins. Collectively, these results indicate a slower cross-bridge attachment rate and a faster detachment rate caused by the R133W β-Tm mutation. It is suggested that the R133W β-Tm mutation induces alteration in myosin–actin kinetics causing a reduced number of myosin molecules in the strong actin-binding state, resulting in overall muscle weakness in the absence of muscle wasting.
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| 7. |
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| 8. |
- Tajsharghi, Homa, 1968, et al.
(författare)
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Distal arthrogryposis and muscle weakness associated with a beta-tropomyosin mutation
- 2007
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Ingår i: Neurology. - : Ovid Technologies (Wolters Kluwer Health). - 1526-632X .- 0028-3878. ; 68:10, s. 772-5
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Tidskriftsartikel (refereegranskat)abstract
- Tropomyosin (TM), a sarcomeric thin-filament protein, plays an essential part in muscle contraction by regulating actin-myosin interaction. We describe two patients, a woman and her daughter, with muscle weakness and distal arthrogryposis (DA) type 2B, caused by a heterozygous missense mutation, R133W, in TPM2, the gene encoding beta-TM. Our results demonstrate the involvement of muscle dysfunction in the pathogenesis of DA and the fact that DA2B may be caused by mutations in TPM2.
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| 9. |
- Tajsharghi, Homa, 1968, et al.
(författare)
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Embryonic myosin heavy-chain mutations cause distal arthrogryposis and developmental myosin myopathy that persists postnatally.
- 2008
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Ingår i: Archives of neurology. - : American Medical Association (AMA). - 1538-3687 .- 0003-9942. ; 65:8, s. 1083-90
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Myosin is a molecular motor and the essential part of the thick filament of striated muscle. The expression of myosin heavy-chain (MyHC) isoforms is developmentally regulated. The embryonic isoform encoded from MYH3 (OMIM *160720) is expressed during fetal life. Recently, mutations in MYH3 were demonstrated to be associated with congenital joint contractures, that is, Freeman-Sheldon and Sheldon-Hall syndromes, which are both distal arthrogryposis syndromes. Mutations in other MyHC isoforms cause myopathy. It is unknown whether MYH3 mutations cause myopathy because muscle tissue has not been studied. OBJECTIVES: To determine whether novel MYH3 mutations are associated with distal arthrogryposis and to demonstrate myopathic changes in muscle biopsy specimens from 4 patients with distal arthrogryposis and MYH3 mutations. DESIGN: In a cohort of patients with distal arthrogryposis, we analyzed the entire coding sequence of MYH3. Muscle biopsy specimens were obtained, and in addition to morphologic analysis, the expression of MyHC isoforms was investigated at the protein and transcript levels. RESULTS: We identified patients from 3 families with novel MYH3 mutations. These mutations affect developmentally conserved residues that are located in different regions of the adenosine triphosphate-binding pocket of the MyHC head. The embryonic (MYH3) isoform was not detected in any of the muscle biopsy samples, indicating a normal developmental downregulation of MYH3 in these patients. However, morphologic analysis of muscle biopsy specimens from the 4 patients revealed mild and variable myopathic features and a pathologic upregulation of the fetal MyHC isoform (MYH8) in 1 patient. CONCLUSIONS: Distal arthrogryposis associated with MYH3 mutations is secondary to myosin myopathy, and postnatal muscle manifestations are variable.
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| 10. |
- Dahan-Oliel, N., et al.
(författare)
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International multidisciplinary collaboration toward an annotated definition of arthrogryposis multiplex congenita
- 2019
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Ingår i: American Journal of Medical Genetics Part C-Seminars in Medical Genetics. - : Wiley. - 1552-4868 .- 1552-4876. ; 181:3, s. 288-299
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Tidskriftsartikel (refereegranskat)abstract
- Arthrogryposis multiplex congenita (AMC) has been described and defined in thousands of articles, but the terminology used has been inconsistent in clinical and research communities. A definition of AMC was recently developed using a modified Delphi consensus method involving 25 experts in the field of AMC from 8 countries. Participants included health care professionals, researchers, and individuals with AMC. An annotation of the definition provides more in-depth explanations of the different sentences of the AMC definition and is useful to complement the proposed definition. The aim of this study was to provide an annotation of the proposed consensus-based AMC definition. For the annotation process, 17 experts in AMC representing 10 disciplines across 7 countries participated. A paragraph was developed for each sentence of the definition using an iterative process involving multiple authors with varied and complementary expertise, ensuring all points of view were taken into consideration. The annotated definition provides an overview of the different topics related to AMC and is intended for all stakeholders, including youth and adults with AMC, their families, and clinicians and researchers, with the hopes of unifying the understanding of AMC in the international community.
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