Detection of deletions within the dystrophin gene in Polish families affected with Duchenne/Becker muscular dystrophy

DNA analysis was performed in 190 cases of Duchenne and Becker muscular dystrophies (DMD/BMD), including 150 cases with DMD and 40 cases with BMD, using Southern blotting and PCR multiplex techniques with application of 25 pairs of primers. Deletions in the overall material were found in 109 cases: 81 (54%) in patients with DMD and 28 (70%) in patients with BMD. All the deletions in DMD were out of frame with the exception of two cases, whereas in BMD all the deletions but two were in frame. Junction fragments were detected in 12 cases of DMD. In five cases duplications were found: four in patients with DMD and one in a patient with BMD.     

肌营养不良蛋白在假肥大肌营养不良症肌组织中的表达研究

目的检测假肥大肌营养不良症肌组织中肌营养不良蛋白（ｄｙｓｔｒｏｐｈｉｎ）的表达。方法用针对ｄｙｓｔｒｏｐｈｉｎ棒状区第１５～１８重复区域的多克隆抗血清Ａｎｔｉ５～７，对２２例Ｄｕｃｈｅｎｎｅ型（ＤＭＤ）和４例Ｂｅｃｋｅｒ型肌营养不良症（ＢＭＤ）患者及１１例无神经肌肉疾病的急诊外伤患者（作为对照）的肌组织进行免疫组化分析。结果在对照组肌细胞中ｄｙｓｔｒｏｐｈｉｎ存在着可达检测水平的表达，并特异地定位于肌细胞膜上。１９例ＤＭＤ没有可达检测水平的ｄｙｓｔｒｏｐｈｉｎ表达，３例ＤＭＤ存在着ｄｙｓｔｒｏｐｈｉｎ表达。４例ＢＭＤ肌细胞膜上则呈现出斑片状、不连续ｄｙｓｔｒｏｐｈｉｎ弱阳性表达。结论ｄｙｓ－ｔｒｏｐｈｉｎ的缺乏是造成ＤＭＤ／ＢＭＤ表型的基本生化因素，此方法为临床上对ＤＭＤ／ＢＭＤ患者作出确诊提供了直接的特异生化测试指标。     

假肥大型肌营养不良症40例临床特征与基因诊断

目的对假肥大型肌营养不良症（DMD／BMD）患者总结其临床特征并进行基因诊断,以提高对DMD／BMD疾病的认识及诊断水平。方法对40例DMD／BMD患者临床特征进行总结包括临床表现、血清肌酶、肌电图及肌肉活检等,并应用18对引物多重PCR的方法对其进行Dystrophin基因缺失诊断。结果DMD／BMD为儿童期隐匿起病、缓慢进行性加重,以肌无力和肌萎缩为特点,主要选择性侵犯四肢近端肌、盆带肌、腰带肌等,可有肌肉假性肥大,有些患者可有智能减退和心肌损害;血清肌酶水平异常增高,肌电图示肌源性损害,肌肉活检呈肌病特征。基因诊断27例存在外显子片段缺失,13例未检测到缺失。结论识别DMD／BMD的临床特征有助于提高对其的诊断水平,多重PCR作为一种简便快速的诊断方法可对DMD／BMD患者进行基因诊断。     

Heterogeneity of dystrophin expression in patients with Duchenne and Becker muscular dystrophy

Summary This report documents the results of an integrated biochemical and immunocytochemical investigation into the expression of dystrophin (the protein product of the Duchenne muscular dystrophy gene) in muscle biopsies from 226 patients. It is the first study in which dystrophin has been analysed on blots and on tissue sections in such a large number of patients using the same (monoclonal) antibody. The 140 patients with Xp21 muscular dystrophy who were included in this study represent a continuous spectrum of disease severity and this range was reflected in the heterogeneity of dystrophin expression which was observed with respect to abundance, size and the pattern of tissue localisation. Approximately 40% of biopsies obtained from patients diagnosed as having Duchenne muscular, dystrophy (DMD) contained isolated clearly positive fibres and a further 20% had very weak labelling on a large number of fibres. Biopsies from patients with Becker muscular dystrophy (BMD) showed labelling patterns which varied from weak labelling on the majority of fibres to clear labelling on all fibres. Typically, however, there was inter-and intra-fibre variation in labelling intensity. Approximately 85% of the 52 BMD and 54 DMD patients who had unequivocal labelling on blots demonstrated a protein of abnormal size. The remaining 15% had a protein of normal size but reduced abundance. Overall, the estimated abundance of dystrophin correlated well with clinical assessments of the disease severity expressed in patients: We conclude that dystrophin analysis is an essential and dependable technique for the differential diagnosis of patients with Xp21 muscular dystrophy.Supported by the University of Newcastle-upon-Tyne Research Committee, the Muscular Dystropy Group of Great Britain and the Medical Research Council     

应用多重连接依赖性探针扩增定量技术检测假肥大型肌营养不良重复突变及携带状态

目的 应用多重连接依赖性探针扩增(MLPA)技术对假肥大型肌营养不良(DMD及BMD)患者及其家系成员进行dystrophin基因分析,探讨MLPA定量技术在本病重复突变及携带者检测中的优势.方法 以355例DMD及BMD患者、46名缺失型患者之母和8名重复型患者之母为研究对象,应用MLPA技术对dystrophin基因全长外显子进行分析,对于单一外显子缺失的样本采用PCR及测序进行验证.结果 经MLPA分析,全部355例患者中190例为dystrophin基因缺失型患者,在其余非缺失型患者中检测出34例重复型突变.此外,在46名缺失型患者的母亲中发现了28名携带者,在8名重复型患者的母亲中发现了6名携带者,两组患者母亲携带者频率差异无统计学意义.经过测序验证,在1例单一外显子缺失的患者中发现17号外显子存在AGGGAACAGATCCTGGTAAAGCA小片段缺失.结论 与传统的定量方法相比,MLPA定量技术可对DMD及BMD患者全长外显子区域同时进行缺失、重复分析,并能对患者家系成员的携带状态进行判定.此外,MLPA检测结果受模板DNA的浓度及纯度影响较小.     

Parental attitudes toward newborn screening for Duchenne/Becker muscular dystrophy and spinal muscular atrophy

Introduction: Disease inclusion in the newborn screening (NBS) panel should consider the opinions of those most affected by the outcome of screening. We assessed the level and factors that affect parent attitudes regarding NBS panel inclusion of Duchenne muscular dystrophy (DMD), Becker muscular dystrophy (BMD), and spinal muscular atrophy (SMA). Methods: The attitudes toward NBS for DMD, BMD, and SMA were surveyed and compared for 2 categories of parents, those with children affected with DMD, BMD, or SMA and expectant parents unselected for known family medical history. Results: The level of support for NBS for DMD, BMD, and SMA was 95.9% among parents of children with DMD, BMD, or SMA and 92.6% among expectant parents. Conclusions: There was strong support for NBS for DMD, BMD, and SMA in both groups of parents. Given advances in diagnostics and promising therapeutic approaches, discussion of inclusion in NBS should continue. Muscle Nerve 49 : 822–828, 2014     

Deletion patterns of dystrophin gene in Hungarian patients with Duchenne/Becker muscular dystrophies

Deletion pattern analysis of the dystrophin gene was performed in 159 Hungarian patients with Duchenne/Becker muscular dystrophy. In 116 cases (73% of total patients), exon deletions were detected by PCR amplification. In 37 patients (31.9% of patients with a deletion) one exon was deleted, while five or more exons were missing in 40 children (34.4%). With respect to the proximal-distal distribution of the deletions, 90 children (77.6%) had deletions exclusively at the 3′ end of the gene, 21 deletions (18.1%) affected only the 5′ end, and in five patients (4.3%) large-scale deletions were detected, which affected both regions. Analysis of the breakpoint distribution pattern in the dystrophin gene showed that, similarly to that observed in several Western European populations, intron 44 was involved most frequently (n=35, 15.1%) as a starting breakpoint. In the Hungarian population introns 50 and 52 were the second (n=30, 12.9%) and third (n=29, 12.5%) most frequently observed hot spots at the 3′ end; these seem to be characteristic for the Hungarian patients. At the 5′ end the breakpoint peak (n=6, 2.58%) was in intron two. As it was proposed by previous national studies, our findings also suggest that certain intronic sequences, characteristic for a population, probably determine the development of a preferential breakpoint profile in this disease.     

Dystrophin-associated protein abnormalities in dystrophin-deficient muscle fibers from symptomatic and asymptomatic Duchenne/Becker muscular dystrophy carriers

The absence of dystrophin in muscle fibers is associated with a major reduction in dystrophin-associated proteins (DAPs) and disruption of the linkage between the subsarcolemmal cytoskeleton and the extracellular matrix. We investigated the expression of the DAPs β-dystroglycan, α-sarcoglycan, γ-sarcoglycan and syntrophin as well as utrophin in the muscles of 13 Duchenne muscular dystrophy (DMD) carriers (with variable percentages of dystrophin-deficient fibers and with a range of clinical symptoms), 2 Becker muscular dystrophy (BMD) carriers (expressing a highly truncated protein in some fibers), 2 girls with a DMD-like phenotype, and 11 BMD carriers with almost normal dystrophin expression (reduced or patchy distribution in a few fibers only and rare dystrophin-deficient fibers). DAPs were highly reduced in all fibers lacking dystrophin in the DMD carriers, but were almost normal in the dystrophin-deficient fibers of the 2 BMD carriers with highly truncated dystrophin. In the 11 BMD carriers with nearly normal dystrophin, the few fibers with reduced or patchy dystrophin immunostaining also showed reduced DAP expression in correlation with dystrophin expression. Immunoblot for β-dystroglycan and α-sarcoglycan confirmed the immunohistochemical findings. Utrophin expression was slightly increased in a proportion of fibers in the DMD and BMD carriers with dystrophin mosaicism. We found no correlation between utrophin expression and DAP expression. We conclude that absence or reduction of dystrophin in muscle fibers of DMD and BMD carriers causes a reduction of DAPs in the same fibers, as observed in DMD and BMD patients, while utrophin does not seem to play a role in DAP expression in adult muscle. Received: 11 January 1996 / Revised, accepted: 16 April 1996     

Sibling concordance for clinical features of Duchenne and Becker muscular dystrophies

Introduction: The correlation of markers of disease severity among brothers with Duchenne or Becker muscular dystrophy has implications for clinical guidance and clinical trials. Methods: Sibling pairs with Duchenne or Becker muscular dystrophy (n = 60) were compared for ages when they reached clinical milestones of disease progression, including ceased ambulation, scoliosis of ≥ 20°, and development of cardiomyopathy. Results: The median age at which younger brothers reached each milestone, compared with their older brothers ranged from 25 months younger for development of cardiomyopathy to 2 months older for ceased ambulation. For each additional month of ambulation by the older brother, the hazard of ceased ambulation by the younger brother decreased by 4%. Conclusions: The ages when siblings reach clinical milestones of disease vary widely between siblings. However, the time to ceased ambulation for older brothers predicts the time to ceased ambulation for their younger brothers. Muscle Nerve 49 : 814–821, 2014     

Long-term electrical stimulation of muscles in children with Duchenne and Becker muscular dystrophy.

Nine children suffering from progressive muscular dystrophy (7 Duchenne and 2 Becker) were included in a program of low-frequency electrical stimulation (LFES) of the right tibialis anterior (TA) muscle. Muscle strength and muscle fatigue were estimated by measuring torques in the ankle during attempts of maximal voluntary contraction (MVC) in the direction of dorsal flexion of the foot and during electrically evoked contractions (EEC). No important increase in the strength of the stimulated muscles was noticed in 4 boys whose muscles were stimulated for 3 months. The muscles of 5 boys who were subjected to electrical stimulation for 9 months showed an improvement; 6 measurements made during the stimulation program revealed that changes of torques in the ankle of the right stimulated extremity were significantly different (P less than 0.001) from the changes of torques in the ankle of the left nonstimulated extremity.     

The abnormal expression of utrophin in Duchenne and Becker muscular dystrophy is age related

J. Taylor, F. Muntoni, V. Dubowitz and C. A. Sewry (1997) Neuropathology and Applied Neurobiology 23, 399–405 The abnormal expression of utrophin in Duchenne and Becker muscular dystrophy is age related Utrophin is a 395 kDa protein with considerable homology to dystrophin. It is highly expressed in the sarcolemma of normal fetal muscle fibres but is confined to neuromuscular and myotendinous junctions, and blood vessels in adult muscle. Sarcolemmal expression occurs on regenerating fibres, irrespective of the disease, and is also seen on mature fibres in Duchenne and Becker muscular dystrophies (DMD, BMD), and inflammatory myopathies. The reasons for the abnormal expression in DMD and BMD are unclear. We have studied this expression of utrophin immunocytochemically on mature fibres in 42 cases of DMD and BMD, aged 3 months–24 years of age. All cases had some mature fibres, with no detectable fetal myosin, that showed sarcolemmal expression of utrophin. The number of these fibres and the intensity of fluorescence was low in young cases before the age of 2 years and increased with age. The fluorescence was graded on a scale of 0 to ++++ and there were significantly more cases under 2 years of age (10/12) with a grading of utrophin of only +, compared with those over 2 years (4/30, P < 0.001). Some revertant fibres, but not all, expressed utrophin and dystrophin. Our data show that the abnormal expression of utrophin on mature muscle fibres in DMD and BMD is not a continuation of the expression that occurs in fetal or regenerating muscle, but is a secondary event caused by unknown factors. The immunocytochemical intensity of utrophin is variable between cases and there is no correlation with clinical severity. As all cases studied had some expression of utrophin on mature fibres, this may be a useful additional tool for distinguishing BMD from other dystrophies, especially in cases with minimal abnormalities in dystrophin expression and/or no detectable mutation in the gene.     

Molecular deletion patterns in Duchenne and Becker muscular dystrophy patients from KwaZulu Natal

There exists much phenotypic heterogeneity in Duchenne muscular dystrophy and its allelic variant, Becker muscular dystrophy. The molecular findings on 53 patients with Duchenne and 15 patients with Becker type muscular dystrophy in KwaZulu Natal, South Africa are reported. Multiplex PCR was performed using primers targeting 18 hot-spot exons throughout the dystrophin gene. Analysis of the multiplex PCR data revealed that 39/68 (57.0%) patients included in the study showed a deletion (33 DMD and 6 BMD patients). Twenty-five patients were Black, 4 were White and 10 were Indian. Using the Chamberlain and Beggs multiplex PCR assays, the region of the genome most frequently affected by a deletion includes exons 47-51. The distal region of the dystrophin gene was most frequently affected by the deletion in both Black and Indian patients. There were too few White patients for conclusions to be drawn concerning the most frequently affected part of the gene. Although the numbers are insufficient to determine whether ethnic differences are present, the Chamberlain and Beggs multiplex PCR assays detect deletions with the same frequency in South African DMD/BMD patients as that reported in the literature.     

MLPA based detection of mutations in the dystrophin gene of 180 Polish families with Duchenne/Becker muscular dystrophy

Duchenne/Becker muscular dystrophy (DMD/BMD) is a recessive, X-linked disorder caused by a mutation in the dystrophin gene. Deletions account for approximately 60–65% of mutations, duplications for 5–10%. The remaining cases are mainly point mutations. According to Monaco theory clinical form of the disease depends on maintaining or disrupting the reading frame. The purpose of the study was to determine frequency and location of deletions and duplications in the dystrophin gene, to determine the compliance between maintaining/disrupting the reading frame and clinical form of the disease and to check the effectiveness of MLPA (multiplex ligation-dependent probe amplification) in the detection of these mutations in hemizygous patients and heterozygous female carriers. The material is composed of combined results of molecular diagnosis carried out in years 2009–2012 in 180 unrelated patients referred with the diagnosis of DMD/BMD tested by use of MLPA. We identified 110 deletions, 22 duplication (in one patient two different duplications were detected) and 2 point mutations. Deletions involved mainly exons 45–54 and 3–21, whereas most duplications involved exons 3–18. The compliance with Monaco theory was 95% for deletions and 76% for duplications. Most of mutations in the dystrophin gene were localized in the hot spots – different for deletions and duplications. MLPA enabled their quick identification, exact localization and determination whether or not they maintained or disrupted the reading frame. MLPA was also effective in detection of deletions and duplications in female carriers.     

Stem cell transplantation for treating Duchenne muscular dystrophy A Web of Science-based literature analysis

OBJECTIVE: To identify global research trends in stem cell transplantation for treating Duchenne muscular dystrophy using a bibliometric analysis of Web of Science. DATA RETRIEVAL: We performed a bibliometric analysis of studies on stem cell transplantation for treating Duchenne muscular dystrophy from 2002 to 2011 retrieved from Web of Science. SELECTION CRITERIA: Inclusion criteria: (a) peer-reviewed published articles on stem cell transplantation for treating Duchenne muscular dystrophy indexed in Web of Science; (b) original research articles, reviews, meeting abstracts, proceedings papers, book chapters, editorial material, and news items; and (c) publication between 2002 and 2011. Exclusion criteria: (a) articles that required manual searching or telephone access; (b) documents that were not published in the public domain; and (c) corrected papers. MAIN OUTCOME MEASURES: (1) Annual publication output; (2) distribution according to subject areas; (3) distribution according to journals; (4) distribution according to country; (5) distribution according to institution; (6) distribution according to institution in China; (7) distribution according to institution that cooperated with Chinese institutions; (8) top-cited articles from 2002 to 2006; (9) top-cited articles from 2007 to 2011. RESULTS: A total of 318 publications on stem cell transplantation for treating Duchenne muscular dystrophy were retrieved from Web of Science from 2002 to 2011, of which almost half derived from American authors and institutes. The number of publications has gradually increased over the past 10 years. Most papers appeared in journals with a focus on gene and molecular research, such as Molecular Therapy, Neuromuscular Disorders, and PLoS One. The 10 most-cited papers from 2002 to 2006 were mostly about different kinds of stem cell transplantation for muscle regeneration, while the 10 most-cited papers from 2007 to 2011 were mostly about new techniques of stem cell transplantation for treating Duchenne muscular dystrophy. CONCLUSION: The publications on stem cell transplantation for treating Duchenne muscular dystrophy were relatively few. It also needs more research to confirm that stem cell therapy is a reliable treatment for Duchenne muscular dystrophy.     

Entries in the Leiden Duchenne muscular dystrophy mutation database: an overview of mutation types and paradoxical cases that confirm the reading-frame rule

The severe Duchenne and milder Becker muscular dystrophy are both caused by mutations in the DMD gene. This gene codes for dystrophin, a protein important for maintaining the stability of muscle-fiber membranes. In 1988, Monaco and colleagues postulated an explanation for the phenotypic difference between Duchenne and Becker patients in the reading-frame rule: In Duchenne patients, mutations induce a shift in the reading frame leading to prematurely truncated, dysfunctional dystrophins. In Becker patients, in-frame mutations allow the synthesis of internally deleted, but largely functional dystrophins. Currently, over 4700 mutations have been reported in the Leiden DMD mutation database, of which 91% are in agreement with this rule. In this study we provide an update of the mutational variability in the DMD gene, particularly focusing on genotype-phenotype correlations and mutations that appear to be exceptions to the reading-frame rule.     

Becker and limb-girdle muscular dystrophy associated with pituitary dwarfism

Summary In 1981 a report appeared of a patient with Duchenne muscular dystrophy associated with dwarfism caused by growth hormone deficiency, in whom the muscular disease was unusually benign. The authors suggested that the benign course might be related to the growth hormone deficiency and dwarfism. Other authors later supported this idea, having observed that in dystrophic mice and hamsters with congenital and experimentally induced pituitary dwarfism, respectively, pathological expressions of the dystrophy were markedly reduced. In this paper one case of Becker and one of limb-girdle dystrophy, each associated with short stature and growth hormone deficiency are described. In these cases the disease did not have a particularly benign course. It is concluded that caution is necessary, at least in certain cases, before an association between reduced muscular growth and the dystrophic process can be assumed.     

Molecular analysis of the duchenne muscular dystrophy gene in patients with becker muscular dystrophy presenting with dilated cardiomyopathy

Molecular analysis of the Duchenne muscular dystrophy (DMD) gene was performed on 4 unrelated patients with Becker muscular dystrophy (BMD) presenting with dilated cardiomyopathy. Two patients with a deletion involving exon 1 were quite unique in that they developed fatal myocardial involvement in their teens, despite the absence of significant muscular weakness. The deletion found in these patients comprised the 3′-end of exon 1 and the greater part of intron 1. Two other patients with a deletion of exon 47 showed progressive muscular atrophy and weakness; they were considered to be typical BMD in both clinical features and the type of gene deletion. We speculate that a deletion around exon 1 may severely damage the expression and/or the function of dystrophin selectively in cardiac muscle, but not in skeletal muscle. © 1993 John Wiley & Sons, Inc.