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Johnson R, Otway R, Chin E, Horvat C, Ohanian M, Wilcox JA, Su Z, Prestes P, Smolnikov A, Soka M, Guo G, Rath E, Chakravorty S, Chrzanowski L, Hayward CS, Keogh AM, Macdonald PS, Giannoulatou E, Chang AC, Oates EC, Charchar F, Seidman JG, Seidman CE, Hegde M, Fatkin D. DMD-Associated Dilated Cardiomyopathy: Genotypes, Phenotypes, and Phenocopies. CIRCULATION. GENOMIC AND PRECISION MEDICINE 2023; 16:421-430. [PMID: 37671549 PMCID: PMC10592075 DOI: 10.1161/circgen.123.004221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Accepted: 07/31/2023] [Indexed: 09/07/2023]
Abstract
BACKGROUND Variants in the DMD gene, that encodes the cytoskeletal protein, dystrophin, cause a severe form of dilated cardiomyopathy (DCM) associated with high rates of heart failure, heart transplantation, and ventricular arrhythmias. Improved early detection of individuals at risk is needed. METHODS Genetic testing of 40 male probands with a potential X-linked genetic cause of primary DCM was undertaken using multi-gene panel sequencing, multiplex polymerase chain reaction, and array comparative genomic hybridization. Variant location was assessed with respect to dystrophin isoform patterns and exon usage. Telomere length was evaluated as a marker of myocardial dysfunction in left ventricular tissue and blood. RESULTS Four pathogenic/likely pathogenic DMD variants were found in 5 probands (5/40: 12.5%). Only one rare variant was identified by gene panel testing with 3 additional multi-exon deletion/duplications found following targeted assays for structural variants. All of the pathogenic/likely pathogenic DMD variants involved dystrophin exons that had percent spliced-in scores >90, indicating high levels of constitutive expression in the human adult heart. Fifteen DMD variant-negative probands (15/40: 37.5%) had variants in autosomal genes including TTN, BAG3, LMNA, and RBM20. Myocardial telomere length was reduced in patients with DCM irrespective of genotype. No differences in blood telomere length were observed between genotype-positive family members with/without DCM and controls. CONCLUSIONS Primary genetic testing using multi-gene panels has a low yield and specific assays for structural variants are required if DMD-associated cardiomyopathy is suspected. Distinguishing X-linked causes of DCM from autosomal genes that show sex differences in clinical presentation is crucial for informed family management.
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Affiliation(s)
- Renee Johnson
- Victor Chang Cardiac Rsrch Inst, Darlinghurst
- School of Clinical Medicine, Faculty of Medicine & Health, UNSW Sydney, Kensington, NSW, Australia
| | - Robyn Otway
- Victor Chang Cardiac Rsrch Inst, Darlinghurst
| | - Ephrem Chin
- Dept of Human Genetics, Emory Univ School of Medicine, Atlanta GA
- PerkinElmer Genomics, PerkinElmer, Waltham
| | | | | | | | - Zheng Su
- School of Biotechnology & Biomolecular Sciences, Faculty of Science, UNSW Sydney, Kensington, NSW, Australia
| | - Priscilla Prestes
- Health Innovation & Transformation Ctr, Federation Univ Australia, Ballarat, Victoria, Australia
| | - Andrei Smolnikov
- School of Biotechnology & Biomolecular Sciences, Faculty of Science, UNSW Sydney, Kensington, NSW, Australia
| | | | | | - Emma Rath
- Victor Chang Cardiac Rsrch Inst, Darlinghurst
- School of Clinical Medicine, Faculty of Medicine & Health, UNSW Sydney, Kensington, NSW, Australia
| | - Samya Chakravorty
- Dept of Human Genetics, Emory Univ School of Medicine, Atlanta GA
- Biocon Bristol Myers Squibb Rsrch & Development Ctr (BBRC), Bangalore, India
| | | | - Christopher S. Hayward
- Victor Chang Cardiac Rsrch Inst, Darlinghurst
- School of Clinical Medicine, Faculty of Medicine & Health, UNSW Sydney, Kensington, NSW, Australia
- Cardiology Dept, St Vincent’s Hospital, Darlinghurst, NSW, Australia
| | - Anne M. Keogh
- Victor Chang Cardiac Rsrch Inst, Darlinghurst
- School of Clinical Medicine, Faculty of Medicine & Health, UNSW Sydney, Kensington, NSW, Australia
- Cardiology Dept, St Vincent’s Hospital, Darlinghurst, NSW, Australia
| | - Peter S. Macdonald
- Victor Chang Cardiac Rsrch Inst, Darlinghurst
- School of Clinical Medicine, Faculty of Medicine & Health, UNSW Sydney, Kensington, NSW, Australia
- Cardiology Dept, St Vincent’s Hospital, Darlinghurst, NSW, Australia
| | - Eleni Giannoulatou
- Victor Chang Cardiac Rsrch Inst, Darlinghurst
- School of Clinical Medicine, Faculty of Medicine & Health, UNSW Sydney, Kensington, NSW, Australia
| | - Alex C.Y. Chang
- Dept of Cardiology & Shanghai Inst of Precision Medicine, Ninth People’s Hospital, Shanghai Jiao Tong Univ School of Medicine, Shanghai, China
- Baxter Laboratory for Stem Cell Biology, Dept of Microbiology & Immunology, Inst for Stem Cell Biology & Regenerative Medicine, Stanford Univ School of Medicine, Stanford, CA
| | - Emily C. Oates
- School of Biotechnology & Biomolecular Sciences, Faculty of Science, UNSW Sydney, Kensington, NSW, Australia
| | - Fadi Charchar
- Health Innovation & Transformation Ctr, Federation Univ Australia, Ballarat, Victoria, Australia
| | - Jonathan G. Seidman
- Dept of Genetics, Harvard Medical School, Boston, MA
- Howard Hughes Medical Inst, Boston
| | - Christine E. Seidman
- Dept of Genetics, Harvard Medical School, Boston, MA
- Cardiovascular Division, Brigham and Women’s Hospital, Boston MA
| | - Madhuri Hegde
- Dept of Human Genetics, Emory Univ School of Medicine, Atlanta GA
- PerkinElmer Genomics, PerkinElmer, Waltham
| | - Diane Fatkin
- Victor Chang Cardiac Rsrch Inst, Darlinghurst
- School of Clinical Medicine, Faculty of Medicine & Health, UNSW Sydney, Kensington, NSW, Australia
- Cardiology Dept, St Vincent’s Hospital, Darlinghurst, NSW, Australia
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2
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Pecorari I, Mestroni L, Sbaizero O. Current Understanding of the Role of Cytoskeletal Cross-Linkers in the Onset and Development of Cardiomyopathies. Int J Mol Sci 2020; 21:E5865. [PMID: 32824180 PMCID: PMC7461563 DOI: 10.3390/ijms21165865] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 07/28/2020] [Accepted: 08/10/2020] [Indexed: 01/08/2023] Open
Abstract
Cardiomyopathies affect individuals worldwide, without regard to age, sex and ethnicity and are associated with significant morbidity and mortality. Inherited cardiomyopathies account for a relevant part of these conditions. Although progresses have been made over the years, early diagnosis and curative therapies are still challenging. Understanding the events occurring in normal and diseased cardiac cells is crucial, as they are important determinants of overall heart function. Besides chemical and molecular events, there are also structural and mechanical phenomena that require to be investigated. Cell structure and mechanics largely depend from the cytoskeleton, which is composed by filamentous proteins that can be cross-linked via accessory proteins. Alpha-actinin 2 (ACTN2), filamin C (FLNC) and dystrophin are three major actin cross-linkers that extensively contribute to the regulation of cell structure and mechanics. Hereby, we review the current understanding of the roles played by ACTN2, FLNC and dystrophin in the onset and progress of inherited cardiomyopathies. With our work, we aim to set the stage for new approaches to study the cardiomyopathies, which might reveal new therapeutic targets and broaden the panel of genes to be screened.
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Affiliation(s)
- Ilaria Pecorari
- Department of Engineering and Architecture, University of Trieste, 34127 Trieste, Italy;
| | - Luisa Mestroni
- University of Colorado Cardiovascular Institute, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA;
| | - Orfeo Sbaizero
- Department of Engineering and Architecture, University of Trieste, 34127 Trieste, Italy;
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3
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Wasala NB, Shin JH, Lai Y, Yue Y, Montanaro F, Duan D. Cardiac-Specific Expression of ΔH2-R15 Mini-Dystrophin Normalized All Electrocardiogram Abnormalities and the End-Diastolic Volume in a 23-Month-Old Mouse Model of Duchenne Dilated Cardiomyopathy. Hum Gene Ther 2018; 29:737-748. [PMID: 29433343 DOI: 10.1089/hum.2017.144] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Heart disease is a major health threat for Duchenne/Becker muscular dystrophy patients and carriers. Expression of a 6-8 kb mini-dystrophin gene in the heart holds promise to change the disease course dramatically. However, the mini-dystrophin gene cannot be easily studied with adeno-associated virus (AAV) gene delivery because the size of the minigene exceeds AAV packaging capacity. Cardiac protection of the ΔH2-R19 minigene was previously studied using the cardiac-specific transgenic approach. Although this minigene fully normalized skeletal muscle force, it only partially corrected electrocardiogram and heart hemodynamics in dystrophin-null mdx mice that had moderate cardiomyopathy. This study evaluated the ΔH2-R15 minigene using the same transgenic approach in mdx mice that had more severe cardiomyopathy. In contrast to the ΔH2-R19 minigene, the ΔH2-R15 minigene carries dystrophin spectrin-like repeats 16 to 19 (R16-19), a region that has been suggested to protect the heart in clinical studies. Cardiac expression of the ΔH2-R15 minigene normalized all aberrant electrocardiogram changes and improved hemodynamics. Importantly, it corrected the end-diastolic volume, an important diastolic parameter not rescued by ΔH2-R19 mini-dystrophin. It is concluded that that ΔH2-R15 mini-dystrophin is a superior candidate gene for heart protection. This finding has important implications in the design of the mini/micro-dystrophin gene for Duchenne cardiomyopathy therapy.
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Affiliation(s)
- Nalinda B Wasala
- 1 Department of Molecular Microbiology and Immunology, The University of Missouri , Columbia, Missouri
| | - Jin-Hong Shin
- 1 Department of Molecular Microbiology and Immunology, The University of Missouri , Columbia, Missouri
| | - Yi Lai
- 1 Department of Molecular Microbiology and Immunology, The University of Missouri , Columbia, Missouri
| | - Yongping Yue
- 1 Department of Molecular Microbiology and Immunology, The University of Missouri , Columbia, Missouri
| | - Federica Montanaro
- 2 Dubowitz Neuromuscular Centre, Molecular Neurosciences Section, Developmental Neurosciences Programme, UCL Great Ormond Street Institute of Child Health , London, United Kingdom
| | - Dongsheng Duan
- 1 Department of Molecular Microbiology and Immunology, The University of Missouri , Columbia, Missouri.,3 Department of Neurology, School of Medicine, The University of Missouri , Columbia, Missouri.,4 Department of Bioengineering, The University of Missouri , Columbia, Missouri.,5 Department of Biomedical Sciences, College of Veterinary Medicine, The University of Missouri , Columbia, Missouri
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4
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Nakamura A, Shiba N, Miyazaki D, Nishizawa H, Inaba Y, Fueki N, Maruyama R, Echigoya Y, Yokota T. Comparison of the phenotypes of patients harboring in-frame deletions starting at exon 45 in the Duchenne muscular dystrophy gene indicates potential for the development of exon skipping therapy. J Hum Genet 2016; 62:459-463. [PMID: 27974813 DOI: 10.1038/jhg.2016.152] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Revised: 11/10/2016] [Accepted: 11/10/2016] [Indexed: 01/07/2023]
Abstract
Exon skipping therapy has recently received attention for its ability to convert the phenotype of lethal Duchenne muscular dystrophy (DMD) to a more benign form, Becker muscular dystrophy (BMD), by correcting the open reading frame. This therapy has mainly focused on a hot-spot (exons 45-55) mutation in the DMD gene. Exon skipping of an entire stretch of exons 45-55 is an approach applicable to 46.9% of DMD patients. However, the resulting phenotype is not yet fully understood. Here we examined the clinical profiles of 24 patients with BMD resulting from deletions starting at exon 45. The Δ45-55 group ranged in age from 2 to 87 years; no mortality was observed, and one patient was ambulatory at 79 years of age. The age at which patients became wheelchair-bound in the Δ45-48 group (18-88 years old) was approximately 50 years. Cardiomyopathy was well controlled by pharmaceuticals in both deletion groups. In contrast, the Δ45-47 and Δ45-49 groups exhibited more severe phenotypes than those with other mutations: the age at which patients in the Δ45-49 group became wheelchair-bound was around 30-40 years. Our study shows that clinical severity differs between each hot-spot deletion.
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Affiliation(s)
- Akinori Nakamura
- Third Department of Medicine, Shinshu University School of Medicine, Matsumoto, Japan.,Department of Neurology, National Hospital Organization, Matsumoto Medical Center, Matsumoto, Japan
| | - Naoko Shiba
- Department of Pediatrics, Shinshu University School of Medicine, Matsumoto, Japan
| | - Daigo Miyazaki
- Third Department of Medicine, Shinshu University School of Medicine, Matsumoto, Japan
| | | | - Yuji Inaba
- Department of Pediatrics, Shinshu University School of Medicine, Matsumoto, Japan
| | - Noboru Fueki
- Division of Rehabilitation, Nagano Children's Hospital, Azumino, Japan
| | - Rika Maruyama
- Department of Medical Genetics, School of Human Development, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Yusuke Echigoya
- Department of Medical Genetics, School of Human Development, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Toshifumi Yokota
- Department of Medical Genetics, School of Human Development, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
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Momma K, Noguchi S, Malicdan MCV, Hayashi YK, Minami N, Kamakura K, Nonaka I, Nishino I. Rimmed vacuoles in Becker muscular dystrophy have similar features with inclusion myopathies. PLoS One 2012; 7:e52002. [PMID: 23251671 PMCID: PMC3522649 DOI: 10.1371/journal.pone.0052002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2012] [Accepted: 11/09/2012] [Indexed: 11/18/2022] Open
Abstract
Rimmed vacuoles in myofibers are thought to be due to the accumulation of autophagic vacuoles, and can be characteristic in certain myopathies with protein inclusions in myofibers. In this study, we performed a detailed clinical, molecular, and pathological characterization of Becker muscular dystrophy patients who have rimmed vacuoles in muscles. Among 65 Becker muscular dystrophy patients, we identified 12 patients who have rimmed vacuoles and 11 patients who have deletions in exons 45–48 in DMD gene. All patients having rimmed vacuoles showed milder clinical features compared to those without rimmed vacuoles. Interestingly, the rimmed vacuoles in Becker muscular dystrophy muscles seem to represent autophagic vacuoles and are also associated with polyubiquitinated protein aggregates. These findings support the notion that rimmed vacuoles can appear in Becker muscular dystrophy, and may be related to the chronic changes in muscle pathology induced by certain mutations in the DMD gene.
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Affiliation(s)
- Kazunari Momma
- Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan
- Department of Neurology, National Defense Medical College, Saitama, Japan
| | - Satoru Noguchi
- Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan
- * E-mail:
| | - May Christine V. Malicdan
- Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Yukiko K. Hayashi
- Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Narihiro Minami
- Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Keiko Kamakura
- Department of Neurology, National Defense Medical College, Saitama, Japan
| | - Ikuya Nonaka
- Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Ichizo Nishino
- Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan
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6
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Diegoli M, Grasso M, Favalli V, Serio A, Gambarin FI, Klersy C, Pasotti M, Agozzino E, Scelsi L, Ferlini A, Febo O, Piccolo G, Tavazzi L, Narula J, Arbustini E. Diagnostic work-up and risk stratification in X-linked dilated cardiomyopathies caused by dystrophin defects. J Am Coll Cardiol 2011; 58:925-34. [PMID: 21851881 DOI: 10.1016/j.jacc.2011.01.072] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/12/2010] [Revised: 12/31/2010] [Accepted: 01/03/2011] [Indexed: 12/01/2022]
Abstract
OBJECTIVES We sought to describe the diagnostic work-up, phenotype, and long-term evolution of dilated cardiomyopathy (DCM) associated with Dystrophin (DYS) defects. BACKGROUND X-linked DCM associated with DYS defects can be clinically indistinguishable from other types of DCM. METHODS The series comprises 436 consecutive male patients diagnosed with DCM. Patients underwent endomyocardial biopsy (EMB). Genetic testing employed multiplex polymerase chain reaction and multiple ligation dependent probe assay for deletions and direct sequencing of the 79 exons and flanking regions of the gene for point mutations or small rearrangements. RESULTS We identified DYS defects in 34 of 436 patients (7.8%) (onset age 34 ± 11 years, age range 17 to 54 years); 30 had proven X-linked inheritance. The 2 phenotypes included DCM with mild skeletal myopathy and/or increased serum creatine phosphokinase (n = 28) or DCM only (n = 6). The EMB showed defective dystrophin immunostain. The DYS defects consisted of 21 in-frame deletions and 11 out-of-frame deletions as well as 1 stop and 1 splice-site mutation. During a median follow-up of 60 months (interquartile range: 11.25 to 101.34 months) we observed 17 events, all related to heart failure (HF) (median event-free survival: 83.5 months). Eight patients (23%) underwent transplantation, and 9 (26%) died of HF while waiting for transplantation. Eight patients received an implantable cardioverter-defibrillator, although none had device intervention during a median follow-up of 14 months (interquartile range: 5 to 25 months). No patient died suddenly, suffered syncope, or developed life-threatening ventricular arrhythmias. CONCLUSIONS DYS-related DCM should be suspected in male patients with increased serum creatine phosphokinase (82%) and X-linked inheritance. The disease shows a high risk of end-stage HF but a lower risk of life-threatening arrhythmias.
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Affiliation(s)
- Marta Diegoli
- Centre for Inherited Cardiovascular Diseases, Istituto Di Ricovero e Cura a Carattere Scientifico (IRCCS) Fondazione Policlinico San Matteo, Pavia, Italy; Department of Pediatric Sciences and Human Pathology, University of Pavia, Pavia, Italy
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7
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Abstract
Dilated cardiomyopathy (DCM) is a myocardial disorder defined by ventricular chamber enlargement and systolic dysfunction. DCM can result in progressive heart failure, arrhythmias, thromboembolism, and premature death, and contributes significantly to health care costs. In many cases, DCM results from acquired factors that affect cardiomyocyte function or survival. Inherited genetic variants are also now recognized to have an important role in the etiology of DCM. Despite substantial progress over the past decade, our understanding of familial DCM remains incomplete. Current concepts of the molecular pathogenesis, clinical presentation, natural history, and management of familial DCM are outlined in this review.
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Affiliation(s)
- Diane Fatkin
- Molecular Cardiology Division, Victor Chang Cardiac Research Institute, 405 Liverpool Street, Darlinghurst, NSW 2010, Australia.
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8
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Miyazaki D, Yoshida K, Fukushima K, Nakamura A, Suzuki K, Sato T, Takeda S, Ikeda SI. Characterization of deletion breakpoints in patients with dystrophinopathy carrying a deletion of exons 45-55 of the Duchenne muscular dystrophy (DMD) gene. J Hum Genet 2009; 54:127-30. [PMID: 19158820 DOI: 10.1038/jhg.2008.8] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Deletion of exons 45-55 (del45-55) in the Duchenne muscular dystrophy gene (DMD) has gained particular interest in the field of molecular therapy, because it causes a milder phenotype than DMD, and therefore, may represent a good candidate for the goal of a multiple exon-skipping strategy. We have precisely characterized deletion breakpoints in three patients with del45-55 in DMD. Two of them were young adult males of the X-linked dilated cardiomyopathy phenotype, and the third patient revealed the mild Becker muscular dystrophy phenotype of late onset. The deletion breakpoints differed among patients. The deletion started at nt 226 604, 231 518, 117 284 in intron 44, and ended at nt 64 994, 59 314, 71 806 in intron 55, respectively. Deletion junctions showed no significant homology between the sequences adjacent to the distal and proximal end joints in these patients. Deletion breakpoints were not primarily associated with any particular sequence element, or with a matrix attachment region. However, there were several palindromic sequences and short tandem repeats at or near the breakpoints. These sequences, with a marked propensity to form secondary DNA structure intermediates, may predispose local DNA to breakage and intragenic recombination in these patients.
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Affiliation(s)
- Daigo Miyazaki
- Department of Medicine (Neurology and Rheumatology), Shinshu University School of Medicine, Nagano, Japan
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Follow-up of three patients with a large in-frame deletion of exons 45-55 in the Duchenne muscular dystrophy (DMD) gene. J Clin Neurosci 2008; 15:757-63. [PMID: 18261911 DOI: 10.1016/j.jocn.2006.12.012] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2006] [Revised: 12/18/2006] [Accepted: 12/22/2006] [Indexed: 11/22/2022]
Abstract
We review the clinical status of skeletal involvement and cardiac function in three unrelated patients harboring an in-frame deletion of exons 45 to 55 in the DMD gene followed up for 2 to 7 years. Two younger patients diagnosed as having X-linked dilated cardiomyopathy (XLDCM) developed congestive heart failure without overt skeletal myopathy. Heart failure recurred after viral infection but responded well to diuretics and angiotensin-converting enzyme inhibitors. One older patient diagnosed with Becker muscular dystrophy showed limb-girdle muscular atrophy and weakness at the age of 50, but did not have any cardiac symptoms. Skeletal muscle involvement in each patient remained unchanged, and cardiac function did not worsen in any of the patients during the study. In a younger XLDCM patient, the amount and molecular weight of mutant dystrophin were equally slightly decreased in both skeletal and cardiac muscles. Immunostaining for dystrophin and dystrophin-associated proteins was slightly reduced in both skeletal and cardiac muscle, with no discernible difference between the two. The phenotype of this dystrophinopathy can manifest as XLDCM in younger patients; however, careful attention to cardiac management may result in a favorable prognosis.
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10
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Abstract
X linked dilated cardiomyopathy is a familial disease that is allelic to Duchenne and Becker muscular dystrophies and caused by mutations in the dystrophin gene. In several families with X linked dilated cardiomyopathy, the pattern of expression of dystrophin mutations in cardiac muscle differs from that in skeletal muscle. A number of these mutations affect transcription and splicing of the dystrophin gene in a tissue specific manner; others may affect regions of dystrophin that are presumed to have a more important role in cardiac than in skeletal muscle. These mutations are important because they highlight the fundamental differences in processing of the dystrophin gene between skeletal and cardiac tissues, as well as differences in the functional domains more relevant for one tissue or the other. This review focuses on the major mechanisms that have been proposed to explain this disorder.
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Affiliation(s)
- N Cohen
- Dubowitz Neuromuscular Unit, Department of Paediatrics, Imperial College London, Hammersmith Hospital Campus, London, UK
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