51
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Morandi L, Mora M, Confalonieri V, Barresi R, Di Blasi C, Brugnoni R, Bernasconi P, Mantegazza R, Dworzak F, Antozzi C. Dystrophin characterization in BMD patients: correlation of abnormal protein with clinical phenotype. J Neurol Sci 1995; 132:146-55. [PMID: 8543940 DOI: 10.1016/0022-510x(95)00147-t] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
We have investigated protein expression and genotype in 59 Becker muscular dystrophy (BMD) patients. The aim was to identify possible causes of the marked variability in phenotype in patients with similar deletions/mutations. The patients were examined neurologically and functionally and underwent Manual Muscle Testing. Dystrophin expression was analysed by immunohistochemistry and western blot using antibodies against six different segments of the protein. DNA mutations were investigated by PCR amplification of 30 exons. Based on dystrophin expression at the sarcolemma, two groups of patients were identified: group A (29 patients) with the classic patchy distribution of dystrophin and group B (30 patients) with absence or reduction of one or more dystrophin portions and variable, although mostly normal, expression of the other portions of the protein. Dystrophin molecular weight was normal or slightly reduced in group A and was variably reduced, generally conspicuously so, in group B. The quantity of dystrophin expressed varied markedly in both groups. The pattern of immunohistochemical staining in group B patients correlated with milder clinical phenotype, suggesting that small dystrophin molecules lacking a portion in the N-terminus or in the rod domain, are more functional than proteins with normal or slightly reduced molecular weight that display the BMD-typical patchy distribution at the sarcolemma.
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Affiliation(s)
- L Morandi
- Department of Neuromuscular Diseases, Istituto Nazionale Neurologico C. Besta, Milan, Italy
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52
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Kaplan JC. [Reflexions apropos of recent progresses in molecular genetics of myopathies]. Arch Pediatr 1995; 2:715-8. [PMID: 7550833 DOI: 10.1016/0929-693x(96)81238-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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53
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Quinlivan R, Ball J, Dunckley M, Thomas DJ, Flinter F, Morgan-Hughes J. Becker muscular dystrophy presenting with complete heart block in the sixth decade. J Neurol 1995; 242:398-400. [PMID: 7561969 DOI: 10.1007/bf00868396] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Becker muscular dystrophy may be associated with myocardial abnormalities which are usually diagnosed after the onset of weakness. We present a patient who developed complete heart block 6 years before the onset of muscle weakness which occurred unusually late at the age of 62 years.
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Affiliation(s)
- R Quinlivan
- Department of Paediatric Neurology, Newcomen Centre, Guy's Hospital, London, UK
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54
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Franz WM, Cremer M, Herrmann R, Grünig E, Fogel W, Scheffold T, Goebel HH, Kircheisen R, Kübler W, Voit T. X-linked dilated cardiomyopathy. Novel mutation of the dystrophin gene. Ann N Y Acad Sci 1995; 752:470-91. [PMID: 7755293 DOI: 10.1111/j.1749-6632.1995.tb17457.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
We report on a family with a severe form of X-linked dilated cardiomyopathy (DCM). Two brothers, the elder requiring heart transplantation, and a maternal cousin presented elevated creatine kinase levels, increased right ventricular diameters and electrocardiographic abnormalities. All complained of exertional cramping myalgia, but none had muscle weakness or a pathological electromyogram. Muscle biopsies of these individuals revealed a mild myopathic picture with atrophic type I and hypertrophic type II fibers. Immunofluorescence using N- and C-terminal antibodies (dys-2, dys-3) against the dystrophin protein showed preserved, but reduced intensity of staining of the sarcolemmal membranes. Using the same two antibodies, Western blot analyses revealed a dystrophin molecule of the expected molecular weight, which was quantitatively reduced by 80%. However, the dys-1 antibody, directed against the mid rod region of the dystrophin protein, did not react with dystrophin both on Western blot and immunofluorescence. Linkage analysis with polymorphic markers of the dystrophin gene revealed an identical haplotype at the 5' region in all affected individuals (two point lod score of 1.93, phi = 0). A deletion of exons 48, 45-53, 2-7 and 1 including the promoter region of the dystrophin gene, as described in rare cases with similar clinical signs could be excluded by multiplex PCR and Southern blot analyses of this DCM family. In addition, a major splice-mutation of dystrophin mRNA was excluded by RT-PCR of skeletal and heart muscle tissue. Therefore, we conclude that a novel mutation in the 5' region of the dystrophin gene phenotypically leads to this severe form of DCM. Extensive analyses of the dystrophin gene, in particular of the sequences coding for the antigenic determinants of the dys-1 antibody in the mid rod region, may identify the molecular cause of this monogenetic form of DCM.
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Affiliation(s)
- W M Franz
- Department of Cardiology, University of Heidelberg, Germany
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55
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Mendell JR, Sahenk Z, Prior TW. The childhood muscular dystrophies: diseases sharing a common pathogenesis of membrane instability. J Child Neurol 1995; 10:150-9. [PMID: 7782608 DOI: 10.1177/088307389501000219] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
New observations demonstrate that several childhood forms of muscular dystrophy share a common pathogenesis. In muscle, dystrophin occurs as part of a membrane complex (dystrophin-glycoprotein) linking the cytoskeleton to the basal lamina. In Duchenne muscular dystrophy, dystrophin deficiency disrupts the linkage of the integral glycoproteins of the sarcolemma and leads to muscle fiber necrosis. In severe childhood autosomal recessive muscular dystrophy, a selective deficiency of adhalin (50-kd glycoprotein) also causes dysfunction of the dystrophin-glycoprotein complex. Most recently, a form of congenital muscular dystrophy demonstrates deficiency of laminin M (merosin) further demonstrating that sarcolemmal instability results from defects in structural proteins of the basal lamina. Animal models have been identified also demonstrating defects in specific proteins linking the subsarcolemmal cytoskeleton to the extracellular matrix. The mdx mouse has a defect in the gene encoding dystrophin. The cardiomyopathic hamster shows a specific deficiency of adhalin in skeletal muscle. The dy/dy mouse has been found deficient in merosin. These animal models will help researchers to understand their human counterparts and provide a system for testing therapeutic strategies.
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Affiliation(s)
- J R Mendell
- Department of Neurology, Ohio State University College of Medicine, Columbus, USA
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56
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57
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Abstract
Dystrophin is a subsarcolemmal protein which is defective in Duchenne and Becker muscular dystrophy (DMD/BMD), and in three animal models. Clinical manifestations of dystrophin deficiency in humans range from a mild calf muscle hypertrophy with cramps to the classical progressive degenerative hypertrophic myopathy of Duchenne. A common feature in the clinical presentation of dystrophin deficiency in humans and in the three documented animal models is the presence of muscle fibre hypertrophy. This paper explores the hypothesis that membrane-bound signalling processes are disrupted in the absence of dystrophin, and suggests that these abnormalities may contribute to both the hypertrophic and degenerative changes of dystrophin deficiency.
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Affiliation(s)
- O Hardiman
- Department of Human Anatomy and Physiology, University College Dublin, Ireland
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58
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Siciliano G, Fanin M, Angelini C, Pollina LE, Miorin M, Saad FA, Freda MP, Muratorio A. Prevalent cardiac involvement in dystrophin Becker type mutation. Neuromuscul Disord 1994; 4:381-6. [PMID: 7981595 DOI: 10.1016/0960-8966(94)90074-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Myocardial involvement is frequently present in Xp21-linked muscular dystrophy, due to a lack of dystrophin in cardiac fibres. We describe a 41-yr-old man affected by dilated cardiomyopathy with sporadic episodes of myoglobinuria induced by effort and increased levels of serum creatine kinase. Very mild signs of skeletal myopathy were clinically evident. His mother was affected by an indefinite cardiopathy and suddenly died when she was 36 yr old. Muscle biopsy of the patient showed a dystrophic process. Dystrophin analysis together with a genetic DMD locus study led us to diagnose Becker type muscular dystrophy, with truncated dystrophin and a gene deletion extending from exon 45 to 48. Prevalent cardiac involvement in a Becker type mutation of the dystrophin gene further confirms clinical variability of dystrophinopathies.
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Affiliation(s)
- G Siciliano
- Institute of Neurology Clinic, University of Pisa, Italy
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59
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Kyriakides T, Gabriel G, Drousiotou A, Meznanic-Petrusa M, Middleton L. Dystrophinopathy presenting as congenital muscular dystrophy. Neuromuscul Disord 1994; 4:387-92. [PMID: 7981596 DOI: 10.1016/0960-8966(94)90075-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
We report a 3 1/2-year-old boy with congenital hypotonia, calf pseudohypertrophy, markedly delayed motor milestones and joint contractures. He was initially diagnosed to have congenital muscular dystrophy on the basis of the age of onset, a myopathic EMG, an elevated creatine kinase and a dystrophic muscle biopsy. Subsequently, dystrophin immunocytochemistry and immunoblot analysis showed complete absence of dystrophin. We suggest that male cases of CMD should undergo dystrophin analysis, if there is calf hypertrophy and markedly elevated CK (> 2000 U/l).
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Affiliation(s)
- T Kyriakides
- Department of Neurology, Cyprus Institute of Neurology and Genetics
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60
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Angelini C, Fanin M, Pegoraro E, Freda MP, Cadaldini M, Martinello F. Clinical-molecular correlation in 104 mild X-linked muscular dystrophy patients: characterization of sub-clinical phenotypes. Neuromuscul Disord 1994; 4:349-58. [PMID: 7981592 DOI: 10.1016/0960-8966(94)90071-x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
A multidisciplinary study was conducted in order to assess dystrophin expression in a large series of mild X-linked muscular dystrophy patients, with well-defined clinical phenotype. Patients (104) were divided in 4 clinical groups, according to clinical severity: asymptomatic (sub-clinical), benign, moderate and severe, Cardiopathy was also assessed, and dilated cardiomyopathy was found in 47% of sub-clinical and benign cases. Myoglobinuria, cramps and myalgia were also associated with a sub-clinical or benign clinical status. Dystrophin immunohistochemical pattern of labelling and dystrophin amount decreased gradually across clinical groups. Our study showed a significative correlation between: (1) dystrophin amount and immunohistochemical score (p < 0.05); (2) dystrophin amount and clinical score (p < 0.05). Therefore, the combined use of these different techniques for prognosis of mild X-linked muscular dystrophy patients is useful. Our study assesses the prevalence of the various disease courses in a large cohort of mild X-linked muscular dystrophy patients. From our series, up to 30% of patients may be either asymptomatic or have sub-clinical changes.
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Affiliation(s)
- C Angelini
- Neuromuscular Center, University of Padova, Italy
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61
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Collins AL, Leyland KG, Kennedy CR, Robinson D, Spratt HC. An inherited dystrophin deletion without muscle weakness. J Med Genet 1994; 31:505. [PMID: 8071981 PMCID: PMC1049939 DOI: 10.1136/jmg.31.6.505] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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62
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Beyenburg S, Zierz S, Arahata K, Mundegar RR, Friedl W, Jerusalem F. Abnormal dystrophin expression in patients with limb girdle syndromes. J Neurol 1994; 241:210-7. [PMID: 8195819 DOI: 10.1007/bf00863770] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Clinical differential diagnosis between Becker muscular dystrophy (BMD) and limb gridle muscular dystrophy (LGMD) may be difficult because the BMD clinical phenotype tends to overlap with other limb girdle syndromes, especially with LGMD. Therefore we studied the expression of dystrophin, the protein product of the Becker and Duchenne muscular dystrophy gene, in muscle biopsy specimens of 30 patients (18 males, of whom 15 represented spradic cases, and 12 females) diagnosed as having LGMD according to traditional clinical, electrophysiological and histological criteria. For dystrophin analysis, six different monoclonal antibodies directed against different epitopes of the dystrophin molecule were used. Immunocytochemically, five of the 30 LGMD patients (17%) showed abnormal dystrophin staining patterns diagnostic of BMD. Western blotting in these five patients, all sporadic cases, showed dystrophin of reduced size and/or abundance. Analysis of blood or muscle DNA using multiplex polymerase chain reaction revealed deletions in the dystrophin gene in three of the five. Thus, 5 of 15 (33%) sporadic male patients previously thought to have LGMD were identified as having BMD.
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Affiliation(s)
- S Beyenburg
- Neurologische Universitätsklinik Bonn, Germany
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63
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Osawa M, Suzuki N, Arai Y, Ikenaka H, Sumida S, Shishikura K, Suzuki H, Fukuyama Y. Fukuyama Type Congenital Progressive Muscular Dystrophy (FCMD) – Special Comment on the Relationship Between the Case Reported by Nakayama et a1 and FCMD –. Neuropathology 1993. [DOI: 10.1111/j.1440-1789.1993.tb00206.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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64
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Melacini P, Fanin M, Danieli GA, Fasoli G, Villanova C, Angelini C, Vitiello L, Miorelli M, Buja GF, Mostacciuolo ML. Cardiac involvement in Becker muscular dystrophy. J Am Coll Cardiol 1993; 22:1927-34. [PMID: 8245351 DOI: 10.1016/0735-1097(93)90781-u] [Citation(s) in RCA: 95] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
OBJECTIVES The purpose of this study was to assess the incidence of myocardial involvement and the relation of cardiac disease to the molecular defect at the deoxyribonucleic acid (DNA) or protein level in Becker muscular dystrophy. BACKGROUND Dystrophin gene mutations produce clinical manifestations of disease in the heart and skeletal muscle of patients with Becker muscular dystrophy. METHODS Thirty-one patients underwent electrocardiographic and echocardiographic examination and 24-h Holter monitoring. The diagnosis was established by neurologic examination, dystrophin immunohistochemical assays or Western blot on muscle biopsy, or both, and DNA analysis. RESULTS Electrocardiographic and echocardiographic findings were abnormal in 68% and 62% of the patients, respectively. Right ventricular involvement was detected in 52%. Left ventricular impairment was observed either as an isolated phenomenon (10%) or in association with right ventricular dysfunction (29%). Right ventricular disease was manifested in the teenagers, and an impairment of the left ventricle was observed in older patients. Right ventricular end-diastolic volumes were significantly increased compared with those in a control group. The left ventricular ejection fraction was significantly lower in older patients than in control subjects or younger patients. Life-threatening ventricular arrhythmias were detected in four patients. No correlations were found between skeletal muscle disease, cardiac involvement and dystrophin abnormalities. In our patients, exon 49 deletion was invariably associated with cardiac involvement. Exon 48 deletion was associated with cardiac disease in all but two patients. CONCLUSIONS The cardiac manifestation of Becker muscular dystrophy is characterized by early right ventricular involvement associated or not with left ventricular impairment. Exon 49 deletion is associated with cardiac disease.
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Affiliation(s)
- P Melacini
- Department of Cardiology, University of Padua, Italy
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65
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Minetti C, Tanji K, Chang HW, Medori R, Cordone G, DiMauro S, Bonilla E. Dystrophinopathy in two young boys with exercise-induced cramps and myoglobinuria. Eur J Pediatr 1993; 152:848-51. [PMID: 8223790 DOI: 10.1007/bf02073385] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Two young boys were referred for evaluation of metabolic myopathy because of elevated serum levels of creatine kinase, cramps and pigmenturia. Immunohistochemical studies of dystrophin in muscle biopsies showed reduced intensity of the stain with a patchy and discontinuous pattern in most fibers. In both patients dystrophin was undetectable by immunoblotting. DNA analysis of the dystrophin gene was not informative in one patient; in the other it revealed an in-frame deletion comprising exons 3-6. These observations suggest that the two patients are affected with an unusual phenotype of Becker muscular dystrophy. Dystrophin analysis should be included in the evaluation of patients with childhood-onset of recurrent myoglobinuria.
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Affiliation(s)
- C Minetti
- Department of Neurology, College of Physicians and Surgeons of Columbia University, New York, NY 10032
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66
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Muntoni F, Cau M, Ganau A, Congiu R, Arvedi G, Mateddu A, Marrosu MG, Cianchetti C, Realdi G, Cao A. Brief report: deletion of the dystrophin muscle-promoter region associated with X-linked dilated cardiomyopathy. N Engl J Med 1993; 329:921-5. [PMID: 8361506 DOI: 10.1056/nejm199309233291304] [Citation(s) in RCA: 325] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- F Muntoni
- Istituto di Neuropsichiatria Infantile, Cagliari, Italy
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67
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Nicholson LV, Johnson MA, Bushby KM, Gardner-Medwin D, Curtis A, Ginjaar IB, den Dunnen JT, Welch JL, Butler TJ, Bakker E. Integrated study of 100 patients with Xp21 linked muscular dystrophy using clinical, genetic, immunochemical, and histopathological data. Part 3. Differential diagnosis and prognosis. J Med Genet 1993; 30:745-51. [PMID: 8411069 PMCID: PMC1016531 DOI: 10.1136/jmg.30.9.745] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
This report is the third part of a trilogy from a multidisciplinary study which was undertaken to investigate gene and protein expression in a large cohort of patients with well defined and diverse clinical phenotypes. The aim of part 3 was to review which of the analytical techniques that we had used would be the most useful for differential diagnosis, and which would provide the most accurate indication of disease severity. Careful clinical appraisal is very important and every DMD patient was correctly diagnosed on this basis. In contrast, half of the sporadic BMD patients and all of the sporadic female patients had received different tentative diagnoses based on clinical assessments alone. Sequential observations of quantitative parameters (such as the time taken to run a fixed distance) were found to be useful clinical indicators for prognosis. Intellectual problems might modify the impression of physical ability in patients presenting at a young age. Histopathological assessment was accurate for DMD but differentiation between BMD and other disorders was more difficult, as was the identification of manifesting carriers. Our data on a small number of women with symptoms of muscle disease indicate that abnormal patterns of dystrophin labelling on sections may be an effective way of differentiating between female patients with a form of limb girdle dystrophy and those carrying a defective Xp21 gene. Dystrophin gene analysis detects deletions/duplications in 50 to 90% of male patients and is the most effective non-invasive technique for diagnosis. Quantitative Western blotting, however, would differentiate between all Xp21 and non-Xp21 male patients. In this study we found a clear relationship between increased dystrophin abundance (determined by densitometric analysis of blots) and clinical condition, with a correlation between dystrophin abundance and the age at loss of independent mobility among boys with DMD and intermediate D/BMD. This indicates that blotting is the most sensitive and accurate technique for diagnosis and prognosis.
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Affiliation(s)
- L V Nicholson
- Muscular Dystrophy Group Research Laboratories, Newcastle General Hospital, Newcastle upon Tyne, UK
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68
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Tachi N, Wakai S, Watanabe Y, Ohya K, Chiba S. Asymptomatic Becker muscular dystrophy: expression of dystrophin and dystrophin-related protein. Pediatr Neurol 1993; 9:207-9. [PMID: 8352853 DOI: 10.1016/0887-8994(93)90086-r] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The expression of dystrophin and a dystrophin-related protein in muscle from 3 asymptomatic Becker muscular dystrophy patients is reported. Histology demonstrated moderate variation in fiber size with clustered basophilic regenerating fibers. Immunostaining for dystrophin revealed a patchy appearance on most fibers, but never on clustered regenerating fibers. Those regenerating fibers did, however, have positive immunoreactivity to a dystrophin-related protein. It is speculated that overexpression of the dystrophin-related protein in regenerating muscle fibers may contribute to the slow progression of muscle weakness or atrophy.
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Affiliation(s)
- N Tachi
- Department of Pediatrics, Sapporo Medical College, Japan
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69
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Doriguzzi C, Palmucci L, Mongini T, Chiadò-Piat L, Restagno G, Ferrone M. Exercise intolerance and recurrent myoglobinuria as the only expression of Xp21 Becker type muscular dystrophy. J Neurol 1993; 240:269-71. [PMID: 8326329 DOI: 10.1007/bf00838159] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
A 9-year-old boy complained of exertional myalgias and described two episodes of myoglobinuria. His family history was negative for neuromuscular diseases. The findings of a neurological examination were normal. Serum creatine kinase was increased, ECG was normal, EMG showed slight "myopathic" signs. Muscle biopsy disclosed a small group of basophilic fibres as the only abnormality. Muscle glycolytic enzymes and carnitine palmitoyl transferase were normal. Immunoblotting using antidystrophin antibody demonstrated a protein with low molecular weight. Genomic DNA analysis showed a deletion of the HindIII fragments spanning from exon 45 to exon 48. Eight years after the first observation the patient has diffuse muscle hypertrophy without muscle weakness.
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Affiliation(s)
- C Doriguzzi
- Paolo Periolo Centre for Neuromuscular Diseases, University of Turin, Italy
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70
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Abstract
Duchenne and Becker muscular dystrophies are caused by defects of the dystrophin gene. Expression of this large X-linked gene is under elaborate transcriptional and splicing control. At least five independent promoters specify the transcription of their respective alternative first exons in a cell-specific and developmentally controlled manner. Three promoters express full-length dystrophin, while two promoters near the C terminus express the last domains in a mutually exclusive manner. Six exons of the C terminus are alternatively spliced, giving rise to several alternative forms. Genetic, biochemical and anatomical studies of dystrophin suggest that a number of distinct functions are subserved by its great structural diversity. Extensive studies of dystrophin may lead to an understanding of the cause and perhaps a rational treatment for muscular dystrophy.
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Affiliation(s)
- A H Ahn
- Program in Neuroscience, Harvard Medical School, Boston, Massachusetts
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71
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Higuchi I, Nakamura K, Nakagawa M, Nakamura N, Usuki F, Inose M, Osame M. Steroid-responsive myalgia in a patient with Becker muscular dystrophy. J Neurol Sci 1993; 115:219-22. [PMID: 7683333 DOI: 10.1016/0022-510x(93)90228-q] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
We report a male patient with exercise-induced focal myalgia in the leg muscles. Dystrophin immunostaining of a biopsied muscle specimen from the patient showed the absence of or only faint immunoreactivity in 20% of the muscle fibers. The patient was diagnosed as having Becker muscular dystrophy. The myalgia was intractable and did not respond to non-steroidal anti-inflammatory drugs. The patient was placed on prednisone and found to be sensitive to it. Although he had recurrences of the symptom during tapering of the steroid, slower tapering over one year was tolerated. Steroid treatment may be useful for other Becker muscular dystrophy patients with myalgia.
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Affiliation(s)
- I Higuchi
- Third Department of Internal Medicine, Faculty of Medicine, Kagoshima University, Japan
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72
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73
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Affiliation(s)
- F Shapiro
- Department of Orthopaedic Surgery, Children's Hospital-Harvard Medical School, Boston, Massachusetts 02115
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74
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Mitani K, Clemens PR, Moseley AB, Caskey CT. Gene transfer therapy for heritable disease: cell and expression targeting. Philos Trans R Soc Lond B Biol Sci 1993; 339:217-24. [PMID: 8097051 DOI: 10.1098/rstb.1993.0019] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Gene therapy is defined as the delivery of a functional gene for expression in somatic tissues with the intent to cure a disease. Different gene transfer strategies may be required to target different tissues. Adenosine deaminase (ADA) deficiency is a good gene therapy model for targeting a rare population of pluripotent hematopoietic stem cells capable of self-renewal. We present evidence for the highly efficient gene transfer and sustained expression of human ADA in human primitive hematopoietic progenitors using retroviral supernatant with a supportive stromal layer. A stem cell-enriched (CD34+) fraction was also successfully transduced. Duchenne muscular dystrophy (DMD) is also a good model for somatic gene therapy. Two of the challenges presented by this model are the large size of the gene and the large number of target cells. Germline gene transfer and correction of the phenotype has been demonstrated in transgenic mdx mice using both a full-length and a truncated form of the dystrophin cDNA. We present here a deletion mutagenesis strategy to truncate the dystrophin cDNA such that it can be accommodated by retroviral and adenoviral vectors useful for somatic gene therapy.
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Affiliation(s)
- K Mitani
- Howard Hughes Medical Institute, Baylor College of Medicine, Houston, Texas 77030
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75
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Bushby KM, Gardner-Medwin D, Nicholson LV, Johnson MA, Haggerty ID, Cleghorn NJ, Harris JB, Bhattacharya SS. The clinical, genetic and dystrophin characteristics of Becker muscular dystrophy. II. Correlation of phenotype with genetic and protein abnormalities. J Neurol 1993; 240:105-12. [PMID: 8437017 DOI: 10.1007/bf00858726] [Citation(s) in RCA: 89] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
We have correlated a detailed clinical assessment of 67 patients with proven Becker muscular dystrophy with the results from genetic and protein analyses. There was an overall deletion frequency of 80%, rising to 92.6% in the large group of patients defined on clinical grounds as being of "typically" mild severity. The deletions in this group were all clustered in the region of the gene between exons 45 and 59; the most common deletion was of exons 45-47 and all but one started at exon 45. No similar deletions were seen in the patients with more severe disease, in whom the diverse genetic defects included a duplication and a very large deletion. Dystrophin patterns in the "typical" group were also very characteristic, and in both groups were as predicted from the genetic defect, the size of deletions being inversely proportional to the size of the protein produced.
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Affiliation(s)
- K M Bushby
- Department of Human Genetics, Newcastle upon Tyne, UK
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76
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Bushby KM, Gardner-Medwin D. The clinical, genetic and dystrophin characteristics of Becker muscular dystrophy. I. Natural history. J Neurol 1993; 240:98-104. [PMID: 8437027 DOI: 10.1007/bf00858725] [Citation(s) in RCA: 105] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
We have investigated 67 patients with proven Becker muscular dystrophy (BMD) using a standard protocol including a detailed history and a functional and clinical examination. Our aim was to define the natural history of the disease in a large cohort of patients in the light of the diagnostic methods now available. In all patients with or without an X-linked family history, the diagnosis was confirmed by the identification of a deletion or other abnormality in the dystrophin gene, and abnormal dystrophin on immunoblotting and immunocytochemistry of muscle biopsy samples. In graphs of functional and muscle score against age, two groups of patients emerged. In the larger group the disease was milder and patients remained ambulant into their forties or beyond. A smaller group had more severe disease with a slightly earlier onset, much earlier loss of ambulation, more frequent abnormal electrocardiographic findings and much lower reproductive fitness. The relationship of these clinical findings to the genetic and protein abnormalities found in the patients is explored in the accompanying paper.
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Affiliation(s)
- K M Bushby
- Department of Human Genetics, Newcastle upon Tyne, UK
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77
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Abstract
The dystrophinopathies are muscle disorders due to an abnormality of an Xp21-linked gene which produces the dystrophin protein. The most common of these disorders are the Duchenne and Becker muscular dystrophies. Modern molecular genetic techniques enable reliable diagnosis and prognosis in many patients, but there are occasional pitfalls. Furthermore, the clinical spectrum of the dystrophinopathies are now such that the clinician needs to be aware of a broader range of clinical disorders that require analysis of the dystrophin gene and its product, not just those that mirror a classic Duchenne or Becker muscular dystrophy picture. This spectrum ranges from a severe form presenting at birth to asymptomatic elevation of CK. Females may be manifesting carriers or present as a severe phenotype when the abnormal gene is expressed as an X-autosome translocation or monosomy X. Laboratory diagnosis and prognosis can be made most accurately by using both DNA analysis at the dystrophin gene and immuno-analysis of muscle with antibodies directed against different regions of the protein product. This review describes some exemplary patients, suggests a clinical classification for dystrophinopathies, and outlines a diagnostic approach.
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Affiliation(s)
- G Miller
- Department of Pediatric Neurology, Texas Children's Hospital, Baylor College of Medicine, Houston 77030
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78
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Rose MR, Howard RS, Genet SA, McMahon CJ, Whitfield A, Morgan-Hughes JA. A case of myopathy associated with a dystrophin gene deletion and abnormal glycogen storage. Muscle Nerve 1993; 16:57-62. [PMID: 8423832 DOI: 10.1002/mus.880160110] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
A 30-year-old man with no family history of muscle disease presented with a progressive proximal myopathy and calf hypertrophy characteristic of Becker muscular dystrophy. A deletion of exons 45 to 48 in the dystrophin gene was confirmed by Southern blotting and multiplex polymerase chain reaction. However, muscle biopsy showed massive accumulation of glycogen, although no significant abnormality of glycolytic pathway enzymes could be demonstrated. This patient therefore has a previously undescribed myopathy associated with both Becker muscular dystrophy and a glycogen storage disorder of unknown aetiology.
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Affiliation(s)
- M R Rose
- Department of Clinical Neurology, Institute of Neurology, London, United Kingdom
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79
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Hoffman EP. Genotype/phenotype correlations in Duchenne/Becker dystrophy. MOLECULAR AND CELL BIOLOGY OF HUMAN DISEASES SERIES 1993; 3:12-36. [PMID: 8111537 DOI: 10.1007/978-94-011-1528-5_2] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- E P Hoffman
- Department of Molecular Genetics and Biochemistry, University of Pittsburgh School of Medicine, Pennsylvania 15261
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80
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Laing NG. Molecular genetics and genetic counselling for Duchenne/Becker muscular dystrophy. MOLECULAR AND CELL BIOLOGY OF HUMAN DISEASES SERIES 1993; 3:37-84. [PMID: 8111545 DOI: 10.1007/978-94-011-1528-5_3] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- N G Laing
- Australian Neuromuscular Research Institute, QEII Medical Centre, Nedlands
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81
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Love DR, Byth BC, Tinsley JM, Blake DJ, Davies KE. Dystrophin and dystrophin-related proteins: a review of protein and RNA studies. Neuromuscul Disord 1993; 3:5-21. [PMID: 8329888 DOI: 10.1016/0960-8966(93)90037-k] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The analysis of dystrophin gene expression has led to the identification of multiple transcripts and varying isoforms. The data indicate that transcription of the dystrophin gene occurs from several promoters, which involves developmental and tissue-dependent regulation. These discoveries have complicated the interpretation of immunolocalization studies, although there is a strong correlation between the amount and size of dystrophin and the severity of the clinical phenotype. The importance of using protein-specific antibodies for dystrophin analysis has been underscored by the identification of a protein, designated utrophin, which exhibits significant sequence homology with dystrophin. This review addresses the recent studies of dystrophin and utrophin expression in an attempt to illustrate the transcriptional diversity of these large genes and the localization of their protein products within various tissues.
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Affiliation(s)
- D R Love
- Department of Pathology, University of Cambridge, U.K
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82
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Minetti C, Bonilla E. Mosaic expression of dystrophin in carriers of Becker's muscular dystrophy and the X-linked syndrome of myalgia and cramps. N Engl J Med 1992; 327:1100. [PMID: 1522852 DOI: 10.1056/nejm199210083271515] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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83
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Affiliation(s)
- K M Bushby
- Department of Human Genetics, Newcastle upon Tyne
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84
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Case records of the Massachusetts General Hospital. Weekly clinicopathological exercises. Case 34-1992. A 19-year-old man with progressive proximal muscle weakness, contractures, and cardiac abnormalities. N Engl J Med 1992; 327:548-57. [PMID: 1635570 DOI: 10.1056/nejm199208203270809] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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85
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Bies RD, Caskey CT, Fenwick R. An intact cysteine-rich domain is required for dystrophin function. J Clin Invest 1992; 90:666-72. [PMID: 1644931 PMCID: PMC443149 DOI: 10.1172/jci115909] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The carboxyl terminus of dystrophin is encoded by a highly conserved, alternatively spliced region of the gene. The few rare mutations reported in this region are of interest in unraveling the function of the dystrophin molecule. An unusual case of infantile onset Duchenne muscular dystrophy (DMD) with an internal 3' genomic deletion, and a membrane localized non-functional dystrophin protein, was used to explore the functional activity of this region. The patient's cDNA sequence showed an intragenic 1824-bp deletion precisely excising the cysteine rich and alternatively spliced COOH-terminal domains of dystrophin. The unaltered final 2.7 kb of the patients transcript was defined as a single exon localized to two genomic fragments, with the 5.9 kb HindIII fragment containing the stop codon. To understand the significance of deletions in this important region of the dystrophin gene, we mapped the order and cDNA coordinates for the 3' genomic HindIII fragments encoding the cysteine rich and alternative splicing domains. This 3' gene map was used to compare the clinical phenotype of the other reported COOH-terminal deletions in the literature. Our analysis concludes that the cysteine-rich domain confers an important function for the dystrophin protein.
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Affiliation(s)
- R D Bies
- Division of Cardiology, Baylor College of Medicine, Houston, Texas 77030
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86
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Rowland LP. The first decade of molecular genetics in neurology: changing clinical thought and practice. Ann Neurol 1992; 32:207-14. [PMID: 1510360 DOI: 10.1002/ana.410320213] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Molecular genetics has had a powerful impact on clinical neurology. Definitions of disease are changing from clinical criteria to DNA analysis, resolving questions about the nature of clinically similar but not identical diseases. Genetic counseling is more reliable. Concepts of mendelian inheritance are being tested and new forms of mutation have been discovered to explain anticipation. Nonmendelian forms of inheritance have emerged; concepts of pathogenesis are on a more secure footing; and novel treatments are being explored.
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Affiliation(s)
- L P Rowland
- Department of Neurology, H. Houston Merritt Clinical Research Center for Muscular Dystrophy and Related Diseases, Columbia-Presbyterian Medical Center, New York, NY 10032-2603
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87
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Abstract
Clinical evidence is presented supporting the hypothesis that the metabolic abnormality in the dystrophin-defective muscular dystrophies (DMD and BMD) involves the ATP pathway. Objective laboratory data show corrective trends in the abnormal values of parameters relating to creatine and calcium metabolism (ATP) by use of glucagon-stimulated c-AMP and by use of synthetically produced adenylosuccinic acid (ASA). Disease accelerating mechanisms as suggested by analysis of the clinical features, and the therapeutic potential of ASA are discussed.
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Affiliation(s)
- C A Bonsett
- Department of Neurology, Indiana University School of Medicine, Indianapolis 46223
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88
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Affiliation(s)
- W J Cumming
- Withington Hospital, West Didsbury, Manchester, UK
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89
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Gold R, Kress W, Meurers B, Meng G, Reichmann H, Müller CR. Becker muscular dystrophy: detection of unusual disease courses by combined approach to dystrophin analysis. Muscle Nerve 1992; 15:214-8. [PMID: 1549142 DOI: 10.1002/mus.880150214] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The rapid progress of research on the structure of the dystrophin gene has enormously increased our understanding of the molecular basis of Duchenne (DMD) and Becker (BMD) muscular dystrophy. Apart from "classical" clinical presentations, asymptomatic or only mildly affected individuals with deletions in the dystrophin gene have now been reported. We describe two families which were initially classified as metabolic myopathies, until the diagnosis of atypical BMD was established after dystrophin analysis at the protein and DNA level. A modern diagnostic approach to myopathies should, therefore, not only include morphological and biochemical investigations, but also be extended to the analysis of the dystrophin gene.
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Affiliation(s)
- R Gold
- Department of Neurology, University of Würzburg, Planegg-Martinsried, Germany
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90
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Abstract
Becker muscular dystrophy is associated with abnormal cardiac features in about 75% of cases; up to one-third will develop ventricular dilatation leading to congestive cardiac failure. As this form of muscular dystrophy is relatively benign, failure to respond to medical treatment warrants assessment for cardiac transplantation.
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Affiliation(s)
- R M Quinlivan
- Marjorie Crowe Neuromuscular Clinic, Guy's Hospital, London, U.K
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91
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Abstract
We have investigated over 100 patients with Xp21 muscular dystrophy, drawing together the results of detailed clinical, genetic and dystrophin investigations. A spectrum of disease severity was confirmed, with the most homogeneous clinical groups being at either end of the spectrum, represented by the typical Duchenne and Becker phenotypes. The groups in between showed clinical heterogeneity, and variability in the genetic and dystrophin results. While an out-of-frame deletion in association with undetectable dystrophin is most likely to predict the most severe phenotype, and increasing abundance of dystrophin is associated generally with a milder clinical course, no value of dystrophin abundance reliably predicts a particular phenotype. However, deletions of the dystrophin gene involving exons 45-47 and 45-48 especially do seem to be consistently associated with the mildest Becker phenotype. Additional factors must play a role in determining the exact clinical course.
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Affiliation(s)
- K M Bushby
- Department of Human Genetics, University of Newcastle upon Tyne, UK
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92
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Hoffman EP, Garcia CA, Chamberlain JS, Angelini C, Lupski JR, Fenwick R. Is the carboxyl-terminus of dystrophin required for membrane association? A novel, severe case of Duchenne muscular dystrophy. Ann Neurol 1991; 30:605-10. [PMID: 1789686 DOI: 10.1002/ana.410300414] [Citation(s) in RCA: 74] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Duchenne muscular dystrophy is a lethal X-linked recessive disorder caused by the deficiency of a component of the muscle fiber membrane cytoskeleton called dystrophin. Becker muscular dystrophy, a clinically milder disorder, results from dystrophin abnormalities rather than deficiency. We identified the first patient who is clearly an exception to these established clinical and biochemical correlates. The patient described clinically had particularly severe Duchenne dystrophy. Biochemically, his muscle contained substantial amounts of abnormal dystrophin (Becker-like). Characterization of the dystrophin protein and gene revealed a unique intragenic gene deletion resulting in a dystrophin protein missing the carboxyl-terminal domain. This patient's dystrophin seemed to have a deleterious "dominant" effect on his muscle: The presence of this abnormal protein was more damaging to the myofibers than the absence of dystrophin would have been. This patient challenges the current hypothesis that dystrophin associates with the plasma membrane solely via its carboxyl-terminus, yet supports the hypothesis that an intact carboxyl-terminus is crucial for correct dystrophin function.
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Affiliation(s)
- E P Hoffman
- Department of Molecular Genetics and Biochemistry, University of Pittsburgh School of Medicine, PA 15261
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93
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Blonden LA, Grootscholten PM, den Dunnen JT, Bakker E, Abbs S, Bobrow M, Boehm C, van Broeckhoven C, Baumbach L, Chamberlain J. 242 breakpoints in the 200-kb deletion-prone P20 region of the DMD gene are widely spread. Genomics 1991; 10:631-9. [PMID: 1679746 DOI: 10.1016/0888-7543(91)90445-k] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Using whole cosmids as probes, we have mapped 242 DMD/BMD deletion breakpoints located in the major deletion hot spot of the DMD gene. Of these, 113 breakpoints were mapped more precisely to individual restriction enzyme fragments in the distal 80 kb of the 170-kb intron 44. An additional 12 breakpoints are distributed over the entire region, with no significant local variation in frequency. Furthermore, deletion sizes vary and are not influenced by the positions of the breakpoints. This argues against a predominant role of one or a few specific sequences in causing frequent rearrangements. It suggests that structural characteristics or a more widespread recombinogenic sequence makes this region so susceptible to deletion. Our study revealed several RFLPs, one of which is a 300-bp insertion/deletion polymorphism. Abnormally migrating junction fragments are found in 81% of the precisely mapped deletions and are highly valuable in the diagnosis of carrier females.
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Affiliation(s)
- L A Blonden
- Department of Human Genetics, Sylvius Laboratory, Leiden, The Netherlands
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94
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Love DR, England SB, Speer A, Marsden RF, Bloomfield JF, Roche AL, Cross GS, Mountford RC, Smith TJ, Davies KE. Sequences of junction fragments in the deletion-prone region of the dystrophin gene. Genomics 1991; 10:57-67. [PMID: 2045110 DOI: 10.1016/0888-7543(91)90484-v] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The Duchenne muscular dystrophy locus is remarkable in that it shows a high mutation rate and the majority of mutations found are deletions. These deletions are generated as meiotic as well as mitotic events and occur preferentially in the central region of the gene. Nothing is known so far about the mechanisms involved. This paper reports the first sequencing of deletion junctions in the dystrophin gene. The data from a study of two patients with deletions in the central region of dystrophin show the breakpoints to lie in regions of introns in which stretches of dA-dT are seen. The relationship between these observations and possible mechanisms for the mutations is discussed.
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Affiliation(s)
- D R Love
- Molecular Genetics Group, John Radcliffe Hospital, Headington, England
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95
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Abstract
We measured the prevalence and incidence of Becker muscular dystrophy in the Northern Health Region of England, UK. Patients were identified from the records of the Regional Neurological Centre and Muscular Dystrophy Group laboratories, Newcastle upon Tyne, and by writing to local doctors. We used cDNA probes and/or dystrophin immunolabelling of muscle-biopsy samples to prove the diagnosis of all cases. Results were compared with the known prevalence and incidence of Duchenne muscular dystrophy. 73 patients alive and resident in the Northern Health Region were identified, giving a prevalence rate of 2.38/100,000. This compares with a prevalence of Duchenne muscular dystrophy of 2.48/100,000. The cumulative birth incidence of Becker muscular dystrophy (at least 1 in 18 450 male live births) was about one third that of Duchenne muscular dystrophy (1 in 5618 male live births), suggesting that the disorder is more common than previously thought.
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Affiliation(s)
- K M Bushby
- Department of Neurobiology and Genetics, University of Newcastle upon Tyne, UK
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96
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Harper PS. Mendelian Inheritance in Man. J Med Genet 1991. [DOI: 10.1136/jmg.28.4.287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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97
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Passos-Bueno MR, Zatz M. Reproductive fitness and frequency of new mutations in Becker muscular dystrophy: implications for genetic risk estimates. J Med Genet 1991; 28:286-7. [PMID: 1856839 PMCID: PMC1016837 DOI: 10.1136/jmg.28.4.286] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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98
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Abstract
Recent advances concerning the genetic and biochemical basis of Duchenne and Becker muscular dystrophies have resulted in a good understanding of the etiology of these common dystrophies. An important secondary consequence of the genetic and biochemical research has been the generation of gene-based and protein-based diagnostic tools which enable a 'molecular diagnosis' for patients and their families. This review summarizes our current understanding of the genetics, biochemistry, and pathophysiology of Duchenne dystrophy, and gives an overview of the molecular diagnostic tools and their applications. Recent correlations of clinical, genetic and biochemical data have indicated that dystrophinopathies can present with a wide range of neuromuscular symptoms, and that neither male sex nor proximal weakness are diagnostic prerequisites for consideration of an underlying dystrophin abnormality.
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Affiliation(s)
- E P Hoffman
- Department of Molecular Genetics and Biochemistry, University of Pittsburgh School of Medicine, PA
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99
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McDonald TD, Medori R, Younger DS, Chang HW, Minetti C, Uncini A, Bonilla E, Hays AP, Lovelace RE. Becker muscular dystrophy or spinal muscular atrophy?--Dystrophin studies resolve conflicting results of electromyography and muscle biopsy. Neuromuscul Disord 1991; 1:195-200. [PMID: 1822794 DOI: 10.1016/0960-8966(91)90024-m] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
We studied a 29-year-old man with slowly progressive proximal leg weakness, calf hypertrophy, and high serum levels of creatine kinase activity. Clinically, it was not possible to identify his as a sporadic instance of Becker muscular dystrophy (BMD) or one of spinal muscular atrophy. The problem arose because electromyography and elevated creatine kinase suggested a myopathy whereas changes in the muscle biopsy resembled a neurogenic disorder. The diagnosis of BMD was made by DNA analysis which detected a deletion at Xp21 and by immunoelectrophoresis and immunohistochemical tests that identified an abnormal form of gene product, dystrophin. These studies were important for genetic counselling, identifying an X-linked disease instead of one that is autosomal recessive.
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Affiliation(s)
- T D McDonald
- Department of Neurology, Columbia Presbyterian Medical Center, New York, NY 10032
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100
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Chelly J, Gilgenkrantz H, Lambert M, Hamard G, Chafey P, Récan D, Katz P, de la Chapelle A, Koenig M, Ginjaar IB. Effect of dystrophin gene deletions on mRNA levels and processing in Duchenne and Becker muscular dystrophies. Cell 1990; 63:1239-48. [PMID: 2261642 DOI: 10.1016/0092-8674(90)90419-f] [Citation(s) in RCA: 114] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Muscle dystrophin mRNAs from Duchenne (DMD) and Becker (BMD) patients with internal deletion of the DMD gene were quantitated and sequenced. In all cases (eight DMD and three BMD), truncated mature transcripts were found, and their amount was correlated to the clinical phenotype and to the reading frame. We focused on four cases that were apparently not in agreement with the reading frame rule. In two DMD cases, slightly reduced amounts of in-frame truncated mRNA are present but no dystrophin is detected, suggesting impaired translation and/or instability of the protein. In two BMD patients with out-of-frame deletions, the presence of minor in-frame alternatively spliced mRNA species is congruent with the observed truncated dystrophin and the mild phenotype.
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Affiliation(s)
- J Chelly
- INSERM U129, Institut Cochin de Génétique Moléculaire, Paris, France
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