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Ma Y, Gui C, Shi M, Wei L, He J, Xie B, Zheng H, Lei X, Wei X, Cheng Z, Zhou X, Chen S, Luo J, Huang Y, Gui B. The cryptic complex rearrangements involving the DMD gene: etiologic clues about phenotypical differences revealed by optical genome mapping. Hum Genomics 2024; 18:103. [PMID: 39285482 PMCID: PMC11406873 DOI: 10.1186/s40246-024-00653-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2024] [Accepted: 08/05/2024] [Indexed: 09/19/2024] Open
Abstract
BACKGROUND Deletion or duplication in the DMD gene is one of the most common causes of Duchenne and Becker muscular dystrophy (DMD/BMD). However, the pathogenicity of complex rearrangements involving DMD, especially segmental duplications with unknown breakpoints, is not well understood. This study aimed to evaluate the structure, pattern, and potential impact of rearrangements involving DMD duplication. METHODS Two families with DMD segmental duplications exhibiting phenotypical differences were recruited. Optical genome mapping (OGM) was used to explore the cryptic pattern of the rearrangements. Breakpoints were validated using long-range polymerase chain reaction combined with next-generation sequencing and Sanger sequencing. RESULTS A multi-copy duplication involving exons 64-79 of DMD was identified in Family A without obvious clinical symptoms. Family B exhibited typical DMD neuromuscular manifestations and presented a duplication involving exons 10-13 of DMD. The rearrangement in Family A involved complex in-cis tandem repeats shown by OGM but retained a complete copy (reading frame) of DMD inferred from breakpoint validation. A reversed insertion with a segmental repeat was identified in Family B by OGM, which was predicted to disrupt the normal structure and reading frame of DMD after confirming the breakpoints. CONCLUSIONS Validating breakpoint and rearrangement pattern is crucial for the functional annotation and pathogenic classification of genomic structural variations. OGM provides valuable insights into etiological analysis of DMD/BMD and enhances our understanding for cryptic effects of complex rearrangements.
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Affiliation(s)
- Yunting Ma
- The Second School of Medicine, Guangxi Medical University, No. 166, Daxuedong Road, Xixiangtang District, Nanning, Guangxi Zhuang Autonomous Region, 530007, China
| | - Chunrong Gui
- Center for Medical Genetics and Genomics, The Second Affiliated Hospital of Guangxi Medical University, No. 166, Daxuedong Road, Xixiangtang District, Nanning, Guangxi Zhuang Autonomous Region, 530007, China
- The Guangxi Health Commission Key Laboratory of Medical Genetics and Genomics, The Second Affiliated Hospital of Guangxi Medical University, No. 166, Daxuedong Road, Xixiangtang District, Nanning, Guangxi Zhuang Autonomous Region, 530007, China
| | - Meizhen Shi
- Center for Medical Genetics and Genomics, The Second Affiliated Hospital of Guangxi Medical University, No. 166, Daxuedong Road, Xixiangtang District, Nanning, Guangxi Zhuang Autonomous Region, 530007, China
- The Guangxi Health Commission Key Laboratory of Medical Genetics and Genomics, The Second Affiliated Hospital of Guangxi Medical University, No. 166, Daxuedong Road, Xixiangtang District, Nanning, Guangxi Zhuang Autonomous Region, 530007, China
| | - Lilin Wei
- Department of Obstetrics, The Second Affiliated Hospital of Guangxi Medical University, No. 166, Daxuedong Road, Xixiangtang District, Nanning, Guangxi Zhuang Autonomous Region, 530007, China
| | - Junfang He
- Department of Rehabilitation Medicine, The Second Affiliated Hospital of Guilin Medical University, No. 212, Renmin Road, Lingui District, Guilin, Guangxi Zhuang Autonomous Region, 541100, China
| | - Bobo Xie
- Center for Medical Genetics and Genomics, The Second Affiliated Hospital of Guangxi Medical University, No. 166, Daxuedong Road, Xixiangtang District, Nanning, Guangxi Zhuang Autonomous Region, 530007, China
- The Guangxi Health Commission Key Laboratory of Medical Genetics and Genomics, The Second Affiliated Hospital of Guangxi Medical University, No. 166, Daxuedong Road, Xixiangtang District, Nanning, Guangxi Zhuang Autonomous Region, 530007, China
| | - Haiyang Zheng
- Center for Medical Genetics and Genomics, The Second Affiliated Hospital of Guangxi Medical University, No. 166, Daxuedong Road, Xixiangtang District, Nanning, Guangxi Zhuang Autonomous Region, 530007, China
- The Guangxi Health Commission Key Laboratory of Medical Genetics and Genomics, The Second Affiliated Hospital of Guangxi Medical University, No. 166, Daxuedong Road, Xixiangtang District, Nanning, Guangxi Zhuang Autonomous Region, 530007, China
| | - Xiaoyun Lei
- Center for Medical Genetics and Genomics, The Second Affiliated Hospital of Guangxi Medical University, No. 166, Daxuedong Road, Xixiangtang District, Nanning, Guangxi Zhuang Autonomous Region, 530007, China
- The Guangxi Health Commission Key Laboratory of Medical Genetics and Genomics, The Second Affiliated Hospital of Guangxi Medical University, No. 166, Daxuedong Road, Xixiangtang District, Nanning, Guangxi Zhuang Autonomous Region, 530007, China
| | - Xianda Wei
- Center for Medical Genetics and Genomics, The Second Affiliated Hospital of Guangxi Medical University, No. 166, Daxuedong Road, Xixiangtang District, Nanning, Guangxi Zhuang Autonomous Region, 530007, China
- The Guangxi Health Commission Key Laboratory of Medical Genetics and Genomics, The Second Affiliated Hospital of Guangxi Medical University, No. 166, Daxuedong Road, Xixiangtang District, Nanning, Guangxi Zhuang Autonomous Region, 530007, China
| | - Zifeng Cheng
- The Second School of Medicine, Guangxi Medical University, No. 166, Daxuedong Road, Xixiangtang District, Nanning, Guangxi Zhuang Autonomous Region, 530007, China
| | - Xu Zhou
- The Second School of Medicine, Guangxi Medical University, No. 166, Daxuedong Road, Xixiangtang District, Nanning, Guangxi Zhuang Autonomous Region, 530007, China
| | - Shaoke Chen
- Department of Pediatrics, The Second Affiliated Hospital of Guangxi Medical University, No. 166, Daxuedong Road, Xixiangtang District, Nanning, Guangxi Zhuang Autonomous Region, 530007, China
| | - Jiefeng Luo
- The Second School of Medicine, Guangxi Medical University, No. 166, Daxuedong Road, Xixiangtang District, Nanning, Guangxi Zhuang Autonomous Region, 530007, China.
- The Guangxi Health Commission Key Laboratory of Medical Genetics and Genomics, The Second Affiliated Hospital of Guangxi Medical University, No. 166, Daxuedong Road, Xixiangtang District, Nanning, Guangxi Zhuang Autonomous Region, 530007, China.
- Department of Neurology, The Second Affiliated Hospital of Guangxi Medical University, No. 166, Daxuedong Road, Xixiangtang District, Nanning, Guangxi Zhuang Autonomous Region, 530007, China.
| | - Yan Huang
- The Second School of Medicine, Guangxi Medical University, No. 166, Daxuedong Road, Xixiangtang District, Nanning, Guangxi Zhuang Autonomous Region, 530007, China.
- The Guangxi Health Commission Key Laboratory of Medical Genetics and Genomics, The Second Affiliated Hospital of Guangxi Medical University, No. 166, Daxuedong Road, Xixiangtang District, Nanning, Guangxi Zhuang Autonomous Region, 530007, China.
- Department of Obstetrics, The Second Affiliated Hospital of Guangxi Medical University, No. 166, Daxuedong Road, Xixiangtang District, Nanning, Guangxi Zhuang Autonomous Region, 530007, China.
| | - Baoheng Gui
- The Second School of Medicine, Guangxi Medical University, No. 166, Daxuedong Road, Xixiangtang District, Nanning, Guangxi Zhuang Autonomous Region, 530007, China.
- Center for Medical Genetics and Genomics, The Second Affiliated Hospital of Guangxi Medical University, No. 166, Daxuedong Road, Xixiangtang District, Nanning, Guangxi Zhuang Autonomous Region, 530007, China.
- The Guangxi Health Commission Key Laboratory of Medical Genetics and Genomics, The Second Affiliated Hospital of Guangxi Medical University, No. 166, Daxuedong Road, Xixiangtang District, Nanning, Guangxi Zhuang Autonomous Region, 530007, China.
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2
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McCormack NM, Calabrese KA, Sun CM, Tully CB, Heier CR, Fiorillo AA. Deletion of miR-146a enhances therapeutic protein restoration in model of dystrophin exon skipping. MOLECULAR THERAPY. NUCLEIC ACIDS 2024; 35:102228. [PMID: 38975000 PMCID: PMC11225849 DOI: 10.1016/j.omtn.2024.102228] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Accepted: 05/22/2024] [Indexed: 07/09/2024]
Abstract
Duchenne muscular dystrophy (DMD) is a progressive muscle disease caused by the absence of dystrophin protein. One current DMD therapeutic strategy, exon skipping, produces a truncated dystrophin isoform using phosphorodiamidate morpholino oligomers (PMOs). However, the potential of exon skipping therapeutics has not been fully realized as increases in dystrophin protein have been minimal in clinical trials. Here, we investigate how miR-146a-5p, which is highly elevated in dystrophic muscle, impacts dystrophin protein levels. We find inflammation strongly induces miR-146a in dystrophic, but not wild-type myotubes. Bioinformatics analysis reveals that the dystrophin 3' UTR harbors a miR-146a binding site, and subsequent luciferase assays demonstrate miR-146a binding inhibits dystrophin translation. In dystrophin-null mdx52 mice, co-injection of miR-146a reduces dystrophin restoration by an exon 51 skipping PMO. To directly investigate how miR-146a impacts therapeutic dystrophin rescue, we generated mdx52 with body-wide miR-146a deletion (146aX). Administration of an exon skipping PMO via intramuscular or intravenous injection markedly increases dystrophin protein levels in 146aX vs. mdx52 muscles while skipped dystrophin transcript levels are unchanged supporting a post-transcriptional mechanism of action. Together, these data show that miR-146a expression opposes therapeutic dystrophin restoration, suggesting miR-146a inhibition warrants further research as a potential DMD exon skipping co-therapy.
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Affiliation(s)
- Nikki M. McCormack
- Center for Genetic Medicine Research, Children’s National Hospital, Washington, DC, USA
| | - Kelsey A. Calabrese
- Center for Genetic Medicine Research, Children’s National Hospital, Washington, DC, USA
| | - Christina M. Sun
- Center for Genetic Medicine Research, Children’s National Hospital, Washington, DC, USA
| | - Christopher B. Tully
- Center for Genetic Medicine Research, Children’s National Hospital, Washington, DC, USA
| | - Christopher R. Heier
- Center for Genetic Medicine Research, Children’s National Hospital, Washington, DC, USA
| | - Alyson A. Fiorillo
- Center for Genetic Medicine Research, Children’s National Hospital, Washington, DC, USA
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3
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Bürger O, Humbel A, Ivanovski I, Baumer A, Rauch A. Further evidence for an attenuated phenotype of in-frame DMD deletions affecting the central rod domain of dystrophin around exon 48. Am J Med Genet A 2024:e63842. [PMID: 39158144 DOI: 10.1002/ajmg.a.63842] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Revised: 07/29/2024] [Accepted: 07/31/2024] [Indexed: 08/20/2024]
Abstract
Alterations in the X-linked recessive DMD gene cause dystrophinopathies with a broad clinical spectrum most commonly ranging from Duchenne muscular dystrophy (DMD) or Becker muscular dystrophy (BMD) to cardiomyopathy or intellectual disability. Carrier females are commonly unaffected but may show signs of dystrophinopathies. In addition, few asymptomatic male carriers with elevated creatine kinase levels have been described possibly related to deletions around exon 48. We now further support this assumed genotype-phenotype correlation by reporting an attenuated phenotype in a three-generation family with a deletion of exon 48 of the DMD gene with clinically unaffected carrier males and females. We confirmed deep intronic breakpoints in this family by genome sequencing, but such data are not available for published cases. Therefore, further observations are needed to clarify genotype-phenotype correlation in this region, since few reports also describe predicted in-frame copy number changes affecting this region in association with classical signs of dystrophinopathies.
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Affiliation(s)
- Olga Bürger
- Institute of Medical Genetics, University of Zurich, Schlieren, Switzerland
| | - Angelika Humbel
- Institute of Medical Genetics, University of Zurich, Schlieren, Switzerland
| | - Ivan Ivanovski
- Institute of Medical Genetics, University of Zurich, Schlieren, Switzerland
| | - Alessandra Baumer
- Institute of Medical Genetics, University of Zurich, Schlieren, Switzerland
| | - Anita Rauch
- Institute of Medical Genetics, University of Zurich, Schlieren, Switzerland
- Pediatric University Hospital Zurich, Zurich, Switzerland
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4
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Pickart AM, Martin AS, Gross BN, Dellefave-Castillo LM, McCallen LM, Nagaraj CB, Rippert AL, Schultz CP, Ulm EA, Armstrong N. Genetic counseling for the dystrophinopathies-Practice resource of the National Society of Genetic Counselors. J Genet Couns 2024. [PMID: 38682751 DOI: 10.1002/jgc4.1892] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 03/06/2024] [Accepted: 03/12/2024] [Indexed: 05/01/2024]
Abstract
The dystrophinopathies encompass the phenotypically variable forms of muscular dystrophy caused by pathogenic variants in the DMD gene. The dystrophinopathies include the most common inherited muscular dystrophy among 46,XY individuals, Duchenne muscular dystrophy, as well as Becker muscular dystrophy and other less common phenotypic variants. With increased access to and utilization of genetic testing in the diagnostic and carrier setting, genetic counselors and clinicians in diverse specialty areas may care for individuals with and carriers of dystrophinopathy. This practice resource was developed as a tool for genetic counselors and other health care professionals to support counseling regarding dystrophinopathies, including diagnosis, health risks and management, psychosocial needs, reproductive options, clinical trials, and treatment. Genetic testing efforts have enabled genotype/phenotype correlation in the dystrophinopathies, but have also revealed unexpected findings, further complicating genetic counseling for this group of conditions. Additionally, the therapeutic landscape for dystrophinopathies has dramatically changed with several FDA-approved therapeutics, an expansive research pathway, and numerous clinical trials. Genotype-phenotype correlations are especially complex and genetic counselors' unique skill sets are useful in exploring and explaining this to families. Given the recent advances in diagnostic testing and therapeutics related to dystrophinopathies, this practice resource is a timely update for genetic counselors and other healthcare professionals involved in the diagnosis and care of individuals with dystrophinopathies.
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Affiliation(s)
- Angela M Pickart
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota, USA
| | - Ann S Martin
- Parent Project Muscular Dystrophy, Washington, District of Columbia, USA
| | - Brianna N Gross
- Department of Neurology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Lisa M Dellefave-Castillo
- Center for Genetic Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| | - Leslie M McCallen
- Department of Pediatrics, University of Colorado School of Medicine, Children's Hospital Colorado, Aurora, Colorado, USA
| | - Chinmayee B Nagaraj
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA
| | - Alyssa L Rippert
- Division of Human Genetics, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | | | - Elizabeth A Ulm
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA
| | - Niki Armstrong
- Parent Project Muscular Dystrophy, Washington, District of Columbia, USA
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5
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Gharibi S, Vaillend C, Lindsay A. The unconditioned fear response in vertebrates deficient in dystrophin. Prog Neurobiol 2024; 235:102590. [PMID: 38484964 DOI: 10.1016/j.pneurobio.2024.102590] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Revised: 01/31/2024] [Accepted: 03/05/2024] [Indexed: 03/19/2024]
Abstract
Dystrophin loss due to mutations in the Duchenne muscular dystrophy (DMD) gene is associated with a wide spectrum of neurocognitive comorbidities, including an aberrant unconditioned fear response to stressful/threat stimuli. Dystrophin-deficient animal models of DMD demonstrate enhanced stress reactivity that manifests as sustained periods of immobility. When the threat is repetitive or severe in nature, dystrophinopathy phenotypes can be exacerbated and even cause sudden death. Thus, it is apparent that enhanced sensitivity to stressful/threat stimuli in dystrophin-deficient vertebrates is a legitimate cause of concern for patients with DMD that could impact neurocognition and pathophysiology. This review discusses our current understanding of the mechanisms and consequences of the hypersensitive fear response in preclinical models of DMD and the potential challenges facing clinical translatability.
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Affiliation(s)
- Saba Gharibi
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Australia
| | - Cyrille Vaillend
- Université Paris-Saclay, CNRS, Institut des Neurosciences Paris-Saclay, Saclay 91400, France.
| | - Angus Lindsay
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Australia; School of Biological Sciences, University of Canterbury, Christchurch 8041, New Zealand; Department of Medicine, University of Otago, Christchurch 8014, New Zealand.
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6
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Gatto F, Benemei S, Piluso G, Bello L. The complex landscape of DMD mutations: moving towards personalized medicine. Front Genet 2024; 15:1360224. [PMID: 38596212 PMCID: PMC11002111 DOI: 10.3389/fgene.2024.1360224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Accepted: 02/26/2024] [Indexed: 04/11/2024] Open
Abstract
Duchenne muscular dystrophy (DMD) is a severe genetic disorder characterized by progressive muscle degeneration, with respiratory and cardiac complications, caused by mutations in the DMD gene, encoding the protein dystrophin. Various DMD mutations result in different phenotypes and disease severity. Understanding genotype/phenotype correlations is essential to optimize clinical care, as mutation-specific therapies and innovative therapeutic approaches are becoming available. Disease modifier genes, trans-active variants influencing disease severity and phenotypic expressivity, may modulate the response to therapy, and become new therapeutic targets. Uncovering more disease modifier genes via extensive genomic mapping studies offers the potential to fine-tune prognostic assessments for individuals with DMD. This review provides insights into genotype/phenotype correlations and the influence of modifier genes in DMD.
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Affiliation(s)
| | | | - Giulio Piluso
- Medical Genetics and Cardiomyology, Department of Precision Medicine, University of Campania “Luigi Vanvitelli”, Napoli, Italy
| | - Luca Bello
- Department of Neurosciences DNS, University of Padova, Padova, Italy
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7
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Clemens PR, Gordish-Dressman H, Niizawa G, Gorni K, Guglieri M, Connolly AM, Wicklund M, Bertorini T, Mah J, Thangarajh M, Smith EC, Kuntz NL, McDonald CM, Henricson E, Upadhyayula S, Byrne B, Manousakis G, Harper A, Iannaccone S, Dang UJ. Findings from the Longitudinal CINRG Becker Natural History Study. J Neuromuscul Dis 2024; 11:201-212. [PMID: 37980682 PMCID: PMC10789327 DOI: 10.3233/jnd-230178] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/18/2023] [Indexed: 11/21/2023]
Abstract
BACKGROUND Becker muscular dystrophy is an X-linked, genetic disorder causing progressive degeneration of skeletal and cardiac muscle, with a widely variable phenotype. OBJECTIVE A 3-year, longitudinal, prospective dataset contributed by patients with confirmed Becker muscular dystrophy was analyzed to characterize the natural history of this disorder. A better understanding of the natural history is crucial to rigorous therapeutic trials. METHODS A cohort of 83 patients with Becker muscular dystrophy (5-75 years at baseline) were followed for up to 3 years with annual assessments. Muscle and pulmonary function outcomes were analyzed herein. Age-stratified statistical analysis and modeling were conducted to analyze cross-sectional data, time-to-event data, and longitudinal data to characterize these clinical outcomes. RESULTS Deletion mutations of dystrophin exons 45-47 or 45-48 were most common. Subgroup analysis showed greater pairwise association between motor outcomes at baseline than association between these outcomes and age. Stronger correlations between outcomes for adults than for those under 18 years were also observed. Using cross-sectional binning analysis, a ceiling effect was seen for North Star Ambulatory Assessment but not for other functional outcomes. Longitudinal analysis showed a decline in percentage predicted forced vital capacity over the life span. There was relative stability or improved median function for motor functional outcomes through childhood and adolescence and decreasing function with age thereafter. CONCLUSIONS There is variable progression of outcomes resulting in significant heterogeneity of the clinical phenotype of Becker muscular dystrophy. Disease progression is largely manifest in adulthood. There are implications for clinical trial design revealed by this longitudinal analysis of a Becker natural history dataset.
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Affiliation(s)
| | | | | | | | - Michela Guglieri
- Newcastle University and Newcastle Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK
| | | | - Matthew Wicklund
- University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | | | - Jean Mah
- Cumming School of Medicine, University of Calgary, Calgary, Canada
| | | | | | | | | | | | | | | | | | - Amy Harper
- Virginia Commonwealth University, Richmond, VA, USA
| | - Susan Iannaccone
- University of Texas Southwestern Medical Center, Dallas, TX, USA
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8
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McCormack NM, Calabrese KA, Sun CM, Tully CB, Heier CR, Fiorillo AA. Deletion of miR-146a enhances therapeutic protein restoration in model of dystrophin exon skipping. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.09.540042. [PMID: 37214870 PMCID: PMC10197665 DOI: 10.1101/2023.05.09.540042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Duchenne muscular dystrophy (DMD) is a progressive muscle disease caused by the absence of dystrophin protein. One current DMD therapeutic strategy, exon skipping, produces a truncated dystrophin isoform using phosphorodiamidate morpholino oligomers (PMOs). However, the potential of exon skipping therapeutics has not been fully realized as increases in dystrophin protein have been minimal in clinical trials. Here, we investigate how miR-146a-5p, which is highly elevated in dystrophic muscle, impacts dystrophin protein levels. We find inflammation strongly induces miR-146a in dystrophic, but not wild-type myotubes. Bioinformatics analysis reveals that the dystrophin 3'UTR harbors a miR-146a binding site, and subsequent luciferase assays demonstrate miR-146a binding inhibits dystrophin translation. In dystrophin-null mdx52 mice, co-injection of miR-146a reduces dystrophin restoration by an exon 51 skipping PMO. To directly investigate how miR-146a impacts therapeutic dystrophin rescue, we generated mdx52 with body-wide miR-146a deletion (146aX). Administration of an exon skipping PMO via intramuscular or intravenous injection markedly increases dystrophin protein levels in 146aX versus mdx52 muscles; skipped dystrophin transcript levels are unchanged, suggesting a post-transcriptional mechanism-of-action. Together, these data show that miR-146a expression opposes therapeutic dystrophin restoration, suggesting miR-146a inhibition warrants further research as a potential DMD exon skipping co-therapy.
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Affiliation(s)
- Nikki M. McCormack
- Center for Genetic Medicine Research, Children’s National Hospital, Washington, District of Columbia, USA
| | - Kelsey A. Calabrese
- Center for Genetic Medicine Research, Children’s National Hospital, Washington, District of Columbia, USA
| | - Christina M. Sun
- Center for Genetic Medicine Research, Children’s National Hospital, Washington, District of Columbia, USA
| | - Christopher B. Tully
- Center for Genetic Medicine Research, Children’s National Hospital, Washington, District of Columbia, USA
| | - Christopher R. Heier
- Center for Genetic Medicine Research, Children’s National Hospital, Washington, District of Columbia, USA
- Department of Genomics and Precision Medicine, George Washington University School of Medicine and Health Sciences, Washington, District of Columbia, USA
| | - Alyson A. Fiorillo
- Center for Genetic Medicine Research, Children’s National Hospital, Washington, District of Columbia, USA
- Department of Genomics and Precision Medicine, George Washington University School of Medicine and Health Sciences, Washington, District of Columbia, USA
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9
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McCormack NM, Nguyen NY, Tully CB, Oliver T, Fiorillo AA, Heier CR. Vamorolone improves Becker muscular dystrophy and increases dystrophin protein in bmx model mice. iScience 2023; 26:107161. [PMID: 37534133 PMCID: PMC10391915 DOI: 10.1016/j.isci.2023.107161] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Revised: 05/15/2023] [Accepted: 06/13/2023] [Indexed: 08/04/2023] Open
Abstract
There is no approved therapy for Becker muscular dystrophy (BMD), a genetic muscle disease caused by in-frame dystrophin deletions. We previously developed the dissociative corticosteroid vamorolone for treatment of the allelic, dystrophin-null disease Duchenne muscular dystrophy. We hypothesize vamorolone can treat BMD by safely reducing inflammatory signaling in muscle and through a novel mechanism of increasing dystrophin protein via suppression of dystrophin-targeting miRNAs. Here, we test this in the bmx mouse model of BMD. Daily oral treatment with vamorolone or prednisolone improves bmx grip strength and hang time phenotypes. Both drugs reduce myofiber size and decrease the percentage of centrally nucleated fibers. Vamorolone shows improved safety versus prednisolone by avoiding or reducing key side effects to behavior and growth. Intriguingly, vamorolone increases dystrophin protein in both heart and skeletal muscle. These data indicate that vamorolone, nearing approval for Duchenne, shows efficacy in bmx mice and therefore warrants clinical investigation in BMD.
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Affiliation(s)
- Nikki M. McCormack
- Center for Genetic Medicine Research, Children’s National Hospital, Washington, DC, USA
| | - Nhu Y. Nguyen
- Center for Genetic Medicine Research, Children’s National Hospital, Washington, DC, USA
| | - Christopher B. Tully
- Center for Genetic Medicine Research, Children’s National Hospital, Washington, DC, USA
| | - Trinitee Oliver
- Center for Genetic Medicine Research, Children’s National Hospital, Washington, DC, USA
- Department of Biology, Howard University, Washington, DC, USA
| | - Alyson A. Fiorillo
- Center for Genetic Medicine Research, Children’s National Hospital, Washington, DC, USA
- Department of Genomics and Precision Medicine, The George Washington University, Washington, DC, USA
| | - Christopher R. Heier
- Center for Genetic Medicine Research, Children’s National Hospital, Washington, DC, USA
- Department of Genomics and Precision Medicine, The George Washington University, Washington, DC, USA
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10
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Bello L, Hoffman EP, Pegoraro E. Is it time for genetic modifiers to predict prognosis in Duchenne muscular dystrophy? Nat Rev Neurol 2023; 19:410-423. [PMID: 37308617 DOI: 10.1038/s41582-023-00823-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/11/2023] [Indexed: 06/14/2023]
Abstract
Patients with Duchenne muscular dystrophy (DMD) show clinically relevant phenotypic variability, despite sharing the same primary biochemical defect (dystrophin deficiency). Factors contributing to this clinical variability include allelic heterogeneity (specific DMD mutations), genetic modifiers (trans-acting genetic polymorphisms) and variations in clinical care. Recently, a series of genetic modifiers have been identified, mostly involving genes and/or proteins that regulate inflammation and fibrosis - processes increasingly recognized as being causally linked with physical disability. This article reviews genetic modifier studies in DMD to date and discusses the effect of genetic modifiers on predicting disease trajectories (prognosis), clinical trial design and interpretation (inclusion of genotype-stratified subgroup analyses) and therapeutic approaches. The genetic modifiers identified to date underscore the importance of progressive fibrosis, downstream of dystrophin deficiency, in driving the disease process. As such, genetic modifiers have shown the importance of therapies aimed at slowing this fibrotic process and might point to key drug targets.
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Affiliation(s)
- Luca Bello
- Department of Neurosciences (DNS), University of Padova, Padova, Italy
| | - Eric P Hoffman
- School of Pharmacy and Pharmaceutical Sciences, Binghamton University (State University of New York), Binghamton, NY, USA
| | - Elena Pegoraro
- Department of Neurosciences (DNS), University of Padova, Padova, Italy.
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11
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Heier CR, McCormack NM, Tully CB, Novak JS, Newell‐Stamper BL, Russell AJ, Fiorillo AA. The X-linked Becker muscular dystrophy (bmx) mouse models Becker muscular dystrophy via deletion of murine dystrophin exons 45-47. J Cachexia Sarcopenia Muscle 2023; 14:940-954. [PMID: 36628607 PMCID: PMC10067474 DOI: 10.1002/jcsm.13171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Revised: 11/22/2022] [Accepted: 12/04/2022] [Indexed: 01/12/2023] Open
Abstract
BACKGROUND Becker muscular dystrophy (BMD) is a genetic neuromuscular disease of growing importance caused by in-frame, partial loss-of-function mutations in the dystrophin (DMD) gene. BMD presents with reduced severity compared with Duchenne muscular dystrophy (DMD), the allelic disorder of complete dystrophin deficiency. Significant therapeutic advancements have been made in DMD, including four FDA-approved drugs. BMD, however, is understudied and underserved-there are no drugs and few clinical trials. Discordance in therapeutic efforts is due in part to lack of a BMD mouse model which would enable greater understanding of disease and de-risk potential therapeutics before first-in-human trials. Importantly, a BMD mouse model is becoming increasingly critical as emerging DMD dystrophin restoration therapies aim to convert a DMD genotype into a BMD phenotype. METHODS We use CRISPR/Cas9 technology to generate bmx (Becker muscular dystrophy, X-linked) mice, which express an in-frame ~40 000 bp deletion of exons 45-47 in the murine Dmd gene, reproducing the most common BMD patient mutation. Here, we characterize muscle pathogenesis using molecular and histological techniques and then test skeletal muscle and cardiac function using muscle function assays and echocardiography. RESULTS Overall, bmx mice present with significant muscle weakness and heart dysfunction versus wild-type (WT) mice, despite a substantial improvement in pathology over dystrophin-null mdx52 mice. bmx mice show impaired motor function in grip strength (-39%, P < 0.0001), wire hang (P = 0.0025), and in vivo as well as ex vivo force assays. In aged bmx, echocardiography reveals decreased heart function through reduced fractional shortening (-25%, P = 0.0036). Additionally, muscle-specific serum CK is increased >60-fold (P < 0.0001), indicating increased muscle damage. Histologically, bmx muscles display increased myofibre size variability (minimal Feret's diameter: P = 0.0017) and centrally located nuclei indicating degeneration/regeneration (P < 0.0001). bmx muscles also display dystrophic pathology; however, levels of the following parameters are moderate in comparison with mdx52: inflammatory/necrotic foci (P < 0.0001), collagen deposition (+1.4-fold, P = 0.0217), and sarcolemmal damage measured by intracellular IgM (P = 0.0878). Like BMD patients, bmx muscles show reduced dystrophin protein levels (~20-50% of WT), whereas Dmd transcript levels are unchanged. At the molecular level, bmx muscles express increased levels of inflammatory genes, inflammatory miRNAs and fibrosis genes. CONCLUSIONS The bmx mouse recapitulates BMD disease phenotypes with histological, molecular and functional deficits. Importantly, it can inform both BMD pathology and DMD dystrophin restoration therapies. This novel model will enable further characterization of BMD disease progression, identification of biomarkers, identification of therapeutic targets and new preclinical drug studies aimed at developing therapies for BMD patients.
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Affiliation(s)
- Christopher R. Heier
- Center for Genetic Medicine ResearchChildren's National HospitalWashingtonDCUSA
- Department of Genomics and Precision MedicineGeorge Washington University School of Medicine and Health SciencesWashingtonDCUSA
| | - Nikki M. McCormack
- Center for Genetic Medicine ResearchChildren's National HospitalWashingtonDCUSA
| | | | - James S. Novak
- Center for Genetic Medicine ResearchChildren's National HospitalWashingtonDCUSA
- Department of Genomics and Precision MedicineGeorge Washington University School of Medicine and Health SciencesWashingtonDCUSA
| | | | - Alan J. Russell
- Edgewise Therapeutics, BioFrontiers InstituteUniversity of ColoradoBoulderCO80303USA
| | - Alyson A. Fiorillo
- Center for Genetic Medicine ResearchChildren's National HospitalWashingtonDCUSA
- Department of Genomics and Precision MedicineGeorge Washington University School of Medicine and Health SciencesWashingtonDCUSA
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12
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Schreyer L, Reilly J, McConkey H, Kerkhof J, Levy MA, Hu J, Hnaini M, Sadikovic B, Campbell C. The discovery of the DNA methylation episignature for Duchenne muscular dystrophy. Neuromuscul Disord 2023; 33:5-14. [PMID: 36572586 DOI: 10.1016/j.nmd.2022.12.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Revised: 11/09/2022] [Accepted: 12/05/2022] [Indexed: 12/13/2022]
Abstract
Duchenne Muscular Dystrophy (DMD) is an X-linked recessive neuromuscular disorder characterized by progressive muscle weakness due to loss of function mutations in the dystrophin gene. Variation in clinical presentation, the rate of disease progression, and treatment responsiveness have been observed amongst DMD patients, suggesting that factors beyond the loss of dystrophin may contribute to DMD pathophysiology. Epigenetic mechanisms are becoming recognized as important factors implicated in the etiology and progression of various diseases. A growing number of genetic syndromes have been associated with unique genomic DNA methylation patterns (called "episignatures") that can be used for diagnostic testing and as disease biomarkers. To further investigate DMD pathophysiology, we assessed the genome-wide DNA methylation profiles of peripheral blood from 36 patients with DMD using the combination of Illumina Infinium Methylation EPIC bead chip array and EpiSign technology. We identified a unique episignature for DMD that whose specificity was confirmed in relation other neurodevelopmental disorders with known episignatures. By modeling the DMD episignature, we developed a new DMD episignature biomarker and provided novel insights into the molecular pathogenesis of this disorder, which have the potential to advance more effective, personalized approaches to DMD care.
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Affiliation(s)
- Leighton Schreyer
- Department of Neuroscience, Western University, London, ON N6A 3K7, Canada
| | - Jack Reilly
- Department of Pathology and Laboratory Medicine, Western University, London, ON N6A 3K7, Canada; Verspeeten Clinical Genome Centre, London Health Sciences Centre, London, ON N6A 5W9, Canada
| | - Haley McConkey
- Verspeeten Clinical Genome Centre, London Health Sciences Centre, London, ON N6A 5W9, Canada
| | - Jennifer Kerkhof
- Verspeeten Clinical Genome Centre, London Health Sciences Centre, London, ON N6A 5W9, Canada
| | - Michael A Levy
- Verspeeten Clinical Genome Centre, London Health Sciences Centre, London, ON N6A 5W9, Canada
| | - Jonathan Hu
- Department of Medicine, Schulich School of Medicine & Dentistry, Western University, London, ON N6A 3K7, Canada
| | - Mona Hnaini
- Department of Pediatrics, Clinical Neurological Sciences, Western University, London, ON N6A 3K7, Canada
| | - Bekim Sadikovic
- Department of Pathology and Laboratory Medicine, Western University, London, ON N6A 3K7, Canada; Verspeeten Clinical Genome Centre, London Health Sciences Centre, London, ON N6A 5W9, Canada.
| | - Craig Campbell
- Department of Pediatrics, Clinical Neurological Sciences and Epidemiology, Western University, London, ON N6A 3K7, Canada.
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13
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Barp A, Carraro E, Goggi G, Lizio A, Zanolini A, Messina C, Perego S, Verdelli C, Lombardi G, Sansone VA, Corbetta S. Body composition and myokines in a cohort of patients with Becker muscular dystrophy. Muscle Nerve 2022; 66:63-70. [PMID: 35474226 PMCID: PMC9321020 DOI: 10.1002/mus.27565] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 04/19/2022] [Accepted: 04/23/2022] [Indexed: 11/13/2022]
Abstract
Introduction/Aims Becker muscular dystrophy (BMD) is an X‐linked disease leading to muscle wasting and weakness. The decrease in lean body mass (LBM) in Duchenne muscular dystrophy, has shown correlation with loss of muscle function and bone density (BD). Myokines (including irisin) are hormones secreted by skeletal muscle that allow crosstalk between muscle and bone. The present study analyzed body composition and circulating myokine levels in a cohort of BMD patients; moreover, the association between dual energy X‐ray absorptiometry (DXA) parameters, functional motor assessments, and myokine levels was investigated. Methods All patients underwent DXA, blood samples for myokine assays, and functional motor assessments. A group of healthy controls (HCs) was also included. Results Thirty BMD patients, median age at evaluation 36.0 y [26.0–41.0], were included. Twenty‐nine patients underwent whole‐body DXA. Median value of total body Z‐score was −0.70. The prevalence of low skeletal muscle mass defined as appendicular skeletal muscle mass index (ASMMI) < 7.59 kg/m2 was 83%. Irisin levels were significantly lower in BMD compared to HCs (p = .03). All DXA parameters showed significant correlation with the functional motor assessments, in particular the h2‐standardized lean mass lower limb index (p = .0006); h2‐standardized total fat mass showed negative correlations with North Star Ambulatory Assessment and 6 min walk test (p = .03). Discussion DXA is a useful tool to evaluate body composition in BMD patients; the decrease in BD and LBM is associated with a reduction of motor function in BMD.
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Affiliation(s)
- Andrea Barp
- Neurorehabilitation Unit, NeMO Clinical Center, University of Milan, Milan, Italy
| | - Elena Carraro
- Neurorehabilitation Unit, NeMO Clinical Center, University of Milan, Milan, Italy
| | - Giovanni Goggi
- Endocrinology and Diabetology Service, IRCCS Istituto Ortopedico Galeazzi, Milan, Italy.,Department of Biotechnology and Translational Medicine, University of Milan, Milan, Italy
| | - Andrea Lizio
- Neurorehabilitation Unit, NeMO Clinical Center, University of Milan, Milan, Italy
| | - Alice Zanolini
- Neurorehabilitation Unit, NeMO Clinical Center, University of Milan, Milan, Italy
| | | | - Silvia Perego
- Laboratory of Experimental Biochemistry & Molecular Biology, IRCCS Istituto Ortopedico Galeazzi, Milan, Italy
| | - Chiara Verdelli
- Laboratory of Experimental Endocrinology, IRCCS Istituto Ortopedico Galeazzi, Milan, Italy
| | - Giovanni Lombardi
- Laboratory of Experimental Biochemistry & Molecular Biology, IRCCS Istituto Ortopedico Galeazzi, Milan, Italy.,Department of Athletics, Strength and Conditioning, Poznań University of Physical Education, Poznań, Poland
| | - Valeria Ada Sansone
- Neurorehabilitation Unit, NeMO Clinical Center, University of Milan, Milan, Italy
| | - Sabrina Corbetta
- Endocrinology and Diabetology Service, IRCCS Istituto Ortopedico Galeazzi, Milan, Italy.,Department of Biomedical, Surgery and Dental Sciences, University of Milan, Milan, Italy
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14
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Ma YL, Zhang WH, Chen GH, Song LF, Wang Y, Yuan RL, Wang Y, Cheng XY. Walking alone milestone combined reading-frame rule improves early prediction of Duchenne muscular dystrophy. Front Pediatr 2022; 10:985878. [PMID: 36034570 PMCID: PMC9417149 DOI: 10.3389/fped.2022.985878] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Accepted: 07/22/2022] [Indexed: 12/05/2022] Open
Abstract
OBJECTIVE To explore the potential of walking alone milestone combined reading-frame rule to improve the early diagnosis of Duchenne muscular dystrophy (DMD). METHOD To retrospectively describe the genotype and phenotype of Duchenne and Becker muscular dystrophies (BMD) patients with deletions and duplicates in the dystrophin gene. The sensitivity and specificity of the reading frame rule were calculated and compared to that of the combined reading frame rule and walking alone milestone. The diagnostic coincidence rate of two different methods was analyzed. RESULT One hundred sixty-nine male DMD/BMD patients were enrolled, including 17 cases of BMD and 152 cases of DMD. The diagnostic coincidence rate, diagnostic sensitivity, and specificity of the reading-frame rule for DMD/BMD were 85.2, 86.8, and 70.59%, respectively. The sensitivity and specificity of the reading frame principle combined with the walking alone milestone for DMD/BMD were 96.05 and 70.59%, respectively. The diagnostic coincidence rate increased to 93.49%, significantly different from that predicted by reading- frame rule (P < 0.05). CONCLUSION The reading-frame rule combined with the walking alone milestone significantly improved the early diagnosis rate of DMD.
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Affiliation(s)
- Yan-Li Ma
- Department of Neonatology, The First Affiliated Hospital of Zheng Zhou University, Zhengzhou, China.,Department of Neurology, Children's Hospital Affiliated to Zhengzhou University, Henan Children's Hospital, Zhengzhou Children's Hospital, Zhengzhou, China
| | - Wei-Hua Zhang
- Department of Neurology, Beijing Children's Hospital, Beijing, China
| | - Guo-Hong Chen
- Department of Neurology, Children's Hospital Affiliated to Zhengzhou University, Henan Children's Hospital, Zhengzhou Children's Hospital, Zhengzhou, China
| | - Li-Fang Song
- Department of Neurology, Children's Hospital Affiliated to Zhengzhou University, Henan Children's Hospital, Zhengzhou Children's Hospital, Zhengzhou, China
| | - Yuan Wang
- Department of Neurology, Children's Hospital Affiliated to Zhengzhou University, Henan Children's Hospital, Zhengzhou Children's Hospital, Zhengzhou, China
| | - Rui-Li Yuan
- Department of Neurology, Children's Hospital Affiliated to Zhengzhou University, Henan Children's Hospital, Zhengzhou Children's Hospital, Zhengzhou, China
| | - Ying Wang
- Department of Neurology, Children's Hospital Affiliated to Zhengzhou University, Henan Children's Hospital, Zhengzhou Children's Hospital, Zhengzhou, China
| | - Xiu-Yong Cheng
- Department of Neonatology, The First Affiliated Hospital of Zheng Zhou University, Zhengzhou, China
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15
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Abstract
Duchenne muscular dystrophy is a severe, progressive, muscle-wasting disease that leads to difficulties with movement and, eventually, to the need for assisted ventilation and premature death. The disease is caused by mutations in DMD (encoding dystrophin) that abolish the production of dystrophin in muscle. Muscles without dystrophin are more sensitive to damage, resulting in progressive loss of muscle tissue and function, in addition to cardiomyopathy. Recent studies have greatly deepened our understanding of the primary and secondary pathogenetic mechanisms. Guidelines for the multidisciplinary care for Duchenne muscular dystrophy that address obtaining a genetic diagnosis and managing the various aspects of the disease have been established. In addition, a number of therapies that aim to restore the missing dystrophin protein or address secondary pathology have received regulatory approval and many others are in clinical development.
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Affiliation(s)
- Dongsheng Duan
- Department of Molecular Microbiology and Immunology and Department of Neurology, School of Medicine; Department of Biomedical Sciences, College of Veterinary Medicine; Department of Biomedical, Biological & Chemical Engineering, College of Engineering, University of Missouri, Columbia, MO, USA
| | - Nathalie Goemans
- Department of Child Neurology, University Hospitals Leuven, Leuven, Belgium
| | | | - Eugenio Mercuri
- Centro Clinico Nemo, Policlinico Gemelli, Rome, Italy
- Peadiatric Neurology, Catholic University, Rome, Italy
| | - Annemieke Aartsma-Rus
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands.
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16
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Zimowski JG, Purzycka J, Pawelec M, Ozdarska K, Zaremba J. Small mutations in Duchenne/Becker muscular dystrophy in 164 unrelated Polish patients. J Appl Genet 2021; 62:289-295. [PMID: 33420945 DOI: 10.1007/s13353-020-00605-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2020] [Revised: 12/09/2020] [Accepted: 12/22/2020] [Indexed: 10/22/2022]
Abstract
In the 164 patients with Duchenne/Becker muscular dystrophy, we found 142 different small mutations including 51 novel mutations not listed in the LOVD, the UMD-DMD, the ClinVar, and the HGMD databases. Among all mutations, nonsense mutations occurred in 45.7%, frameshift mutations in 32.9%, and splicing mutations in 19.5%. Small mutations were distributed throughout the whole dystrophin gene. Splicing mutations were twice more common in BMD patients than in DMD patients. Eighty-two percent of mothers of the males affected with DMD/BMD were found to be carriers of small mutations.
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Affiliation(s)
- Janusz G Zimowski
- Department of Genetics, Institute of Psychiatry and Neurology, 02-957, Sobieskiego 9, Warsaw, Poland. .,, Warsaw, Poland.
| | - Joanna Purzycka
- Department of Genetics, Institute of Psychiatry and Neurology, 02-957, Sobieskiego 9, Warsaw, Poland
| | - Magdalena Pawelec
- Department of Genetics, Institute of Psychiatry and Neurology, 02-957, Sobieskiego 9, Warsaw, Poland
| | - Katarzyna Ozdarska
- Department of Genetics, Institute of Psychiatry and Neurology, 02-957, Sobieskiego 9, Warsaw, Poland
| | - Jacek Zaremba
- Department of Genetics, Institute of Psychiatry and Neurology, 02-957, Sobieskiego 9, Warsaw, Poland
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17
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Clemens PR, Niizawa G, Feng J, Florence J, DʼAlessandro AS, Morgenroth LP, Gorni K, Guglieri M, Connolly A, Wicklund M, Bertorini T, Mah JK, Thangarajh M, Smith E, Kuntz N, McDonald CM, Henricson EK, Upadhyayula S, Byrne B, Manousakis G, Harper A, Bravver E, Iannaccone S, Spurney C, Cnaan A, Gordish-Dressman H. The CINRG Becker Natural History Study: Baseline characteristics. Muscle Nerve 2020; 62:369-376. [PMID: 32564389 DOI: 10.1002/mus.27011] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Revised: 06/16/2020] [Accepted: 06/17/2020] [Indexed: 01/16/2023]
Abstract
We performed an observational, natural history study of males with in-frame dystrophin gene deletions causing Becker muscular dystrophy (BMD). A prospective natural history study collected longitudinal medical, strength, and timed function assessments. Eighty-three participants with genetically confirmed BMD were enrolled (age range 5.6-75.4 years). Lower extremity function and the percentage of participants who retained ambulation declined across the age span. The largest single group of participants had in-frame deletions that corresponded to an out-of-frame deletion treated with an exon 45 skip to restore the reading frame. This group of 54 participants showed similarities in baseline motor functional assessments when compared to the group of all others in the study. A prospective natural history cohort with in-frame dystrophin gene deletions offers the potential to contribute to clinical trial readiness for BMD and to analyze therapeutic benefit of exon skipping for Duchenne muscular dystrophy.
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Affiliation(s)
- Paula R Clemens
- Department of Veterans Affairs Medical Center and University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Gabriela Niizawa
- University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Jia Feng
- Children's National Medical Center, Washington, DC, USA
| | | | | | | | | | | | | | | | | | - Jean K Mah
- Alberta Children's Hospital, Calgary, Alberta, Canada
| | | | - Edward Smith
- Duke University Medical Center, Durham, North Carolina, USA
| | - Nancy Kuntz
- Lurie Children's Hospital, Chicago, Illinois, USA
| | | | | | | | - Barry Byrne
- University of Florida, Gainesville, Florida, USA
| | | | - Amy Harper
- Carolinas Medical Center, Charlotte, North Carolina, USA
| | - Elena Bravver
- Carolinas Medical Center, Charlotte, North Carolina, USA
| | - Susan Iannaccone
- University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | | | - Avital Cnaan
- Children's National Medical Center, Washington, DC, USA
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18
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Exon skipping induced by nonsense/frameshift mutations in DMD gene results in Becker muscular dystrophy. Hum Genet 2020; 139:247-255. [PMID: 31919629 PMCID: PMC6981323 DOI: 10.1007/s00439-019-02107-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2019] [Accepted: 12/27/2019] [Indexed: 01/13/2023]
Abstract
Duchenne muscular dystrophy (DMD) is caused by a nonsense or frameshift mutation in the DMD gene, while its milder form, Becker muscular dystrophy (BMD) is caused by an in-frame deletion/duplication or a missense mutation. Interestingly, however, some patients with a nonsense mutation exhibit BMD phenotype, which is mostly attributed to the skipping of the exon containing the nonsense mutation, resulting in in-frame deletion. This study aims to find BMD cases with nonsense/frameshift mutations in DMD and to investigate the exon skipping rate of those nonsense/frameshift mutations. We searched for BMD cases with nonsense/frameshift mutations in DMD in the Japanese Registry of Muscular Dystrophy. For each DMD mutation identified, we constructed minigene plasmids containing one exon with/without a mutation and its flanking intronic sequence. We then introduced them into HeLa cells and measured the skipping rate of transcripts of the minigene by RT-qPCR. We found 363 cases with a nonsense/frameshift mutation in DMD gene from a total of 1497 dystrophinopathy cases in the registry. Among them, 14 had BMD phenotype. Exon skipping rates were well correlated with presence or absence of dystrophin, suggesting that 5% exon skipping rate is critical for the presence of dystrophin in the sarcolemma, leading to milder phenotypes. Accurate quantification of the skipping rate is important in understanding the exact functions of the nonsense/frameshift mutations in DMD and for interpreting the phenotypes of the BMD patients.
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19
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Abstract
Drug development and pharmacotherapy of rare pediatric diseases have significantly expanded over the last decade, in part due to incentives and financial support provided by governments, regulators, and nonprofit foundations. Duchenne muscular dystrophy (DMD) is among the most common rare pediatric disorders, and clinical trials of therapeutic approaches have seen dramatic expansion. Pharmacotherapeutic standard of care has been limited to off-label prescription of high-dose, daily corticosteroids (prednisone, deflazacort). Deflazacort received FDA approval for DMD in 2016, although the price increases associated with formal FDA approval and the severe side effects associated with corticosteroid use have limited patient/physician uptake and insurance coverage in the USA. In Europe, EMA has given conditional marketing authorization for prescription of Translarna (a stop codon read-through drug prescribed to ~10% of DMD patients), although there is not yet evidence of clinical efficacy. The FDA awarded conditional approval to etiplirsen, an exon-skipping oligonucleotide drug, based on accelerated pathways (increased dystrophin production in patient muscle). Evidence of clinical efficacy remains the focus of post-marketing studies. There are many innovative pharmacotherapies under clinical development for DMD (Phase I, II, and III clinical trials). All are "disease modifying" in the sense that none seek to replace the full-length, normal DMD gene or dystrophin protein, but instead either seek to introduce an abnormal "Becker-like" version of the gene or protein or target pathophysiological pathways downstream of the primary defect. It is envisioned that the most significant benefit to DMD patients will be through multidrug approaches simultaneously aiming to introduce partially functional dystrophin in patient muscle while also targeting both chronic inflammation and the fibrofatty replacement of muscle.
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Affiliation(s)
- Eric P Hoffman
- Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, Binghamton University State University of New York, Binghamton, NY, USA.
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20
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Breakpoint junction features of seven DMD deletion mutations. Hum Genome Var 2019; 6:39. [PMID: 31645977 PMCID: PMC6804640 DOI: 10.1038/s41439-019-0070-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2019] [Revised: 07/22/2019] [Accepted: 07/23/2019] [Indexed: 11/25/2022] Open
Abstract
Duchenne muscular dystrophy is an inherited muscle wasting disease with severe symptoms and onset in early childhood. Duchenne muscular dystrophy is caused by loss-of-function mutations, most commonly deletions, within the DMD gene. Characterizing the junction points of large genomic deletions facilitates a more detailed model of the origins of these mutations and allows for a greater understanding of phenotypic variations associated with particular genotypes, potentially providing insights into the deletion mechanism. Here, we report sequencing of breakpoint junctions for seven patients with intragenic, whole-exon DMD deletions. Of the seven junction sequences identified, we found one instance of a “clean” break, three instances of microhomology (2–5 bp) at the junction site, and three complex rearrangements involving local sequences. Bioinformatics analysis of the upstream and downstream breakpoint regions revealed a possible role of short inverted repeats in the initiation of some of these deletion events. Researchers in Australia have identified new examples of the genomic factors and mechanisms that lead to deletions linked with Duchenne muscular dystrophy (DMD). DMD is an inherited neuromuscular disease which causes progressive deterioration of muscles and, in some cases, intellectual impairment. Using samples from seven DMD patients, Niall Keegan of Murdoch University in Perth and colleagues sequenced the DNA left behind around the deletions in the DMD gene which cause the disease. They found one clean break, three sections with short repeated sequences, and three with more complex rearrangements. The diversity of these findings led them to suggest that the deletions resulted from a diversity of genomic factors and repair mechanisms. Future work could incorporate these findings into a model to predict where deletions will occur, expanding our understanding of DMD and its causes.
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21
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Andrews JG, Lamb MM, Conway K, Street N, Westfield C, Ciafaloni E, Matthews D, Cunniff C, Pandya S, Fox DJ. Diagnostic Accuracy of Phenotype Classification in Duchenne and Becker Muscular Dystrophy Using Medical Record Data1. J Neuromuscul Dis 2019; 5:481-495. [PMID: 30320597 DOI: 10.3233/jnd-180306] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Dystrophinopathies are caused by mutations in DMD resulting in progressive muscle weakness. They are historically divided into the more severe Duchenne (DMD) and milder Becker (BMD) muscular dystrophy phenotypes. Classification is important for research and clinical care. The purpose of this study was to describe a multi-variable approach to classifying cases from the Muscular Dystrophy Surveillance, Tracking, and Research Network (MD STARnet) and to assess the accuracy of the diagnostic classification scheme. We used age at loss of mobility, molecular testing results, and age at symptom onset to classify cases as having DMD or BMD and to assess sensitivity and specificity. Mobility status showed low sensitivity and high specificity for predicting DMD (65.5% and 99.3%, respectively) and BMD (62.8% and 97.7%, respectively) phenotypes. Molecular testing showed 90.9% sensitivity and 66.4% specificity for DMD; 76.3% sensitivity and 90.0% specificity for BMD. Age of onset predicted DMD with sensitivity of 73.9% and specificity of 69.0%; BMD had 99.7% specificity and 36.7% sensitivity. Mobility status, molecular test results, and age at symptom onset are important but inconsistent measures for accurately classifying individuals into DMD or BMD phenotypes. These results have implications for prognosis in newly diagnosed individuals and for classifying phenotype in clinical trials.
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Affiliation(s)
| | - Molly M Lamb
- Department of Epidemiology, Colorado School of Public Health, University of Colorado, Aurora, Colorado, USA
| | - Kristin Conway
- Department of Epidemiology, The University of Iowa, Iowa City, Iowa, USA
| | - Natalie Street
- National Center on Birth Defects and Developmental Disabilities, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | | | - Emma Ciafaloni
- Department of Neurology, School of Medicine and Dentistry, University of Rochester Medical Center, Rochester, New York, USA
| | - Dennis Matthews
- Physical Medicine and Rehabilitation, School of Medicine, University of Colorado, Aurora, Colorado, USA
| | - Christopher Cunniff
- Department of Pediatrics, Weill Cornell Medical College, New York, New York, USA
| | - Shree Pandya
- Department of Neurology, School of Medicine and Dentistry, University of Rochester Medical Center, Rochester, New York, USA
| | - Deborah J Fox
- New York State Department of Health, Albany, New York, USA
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22
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Wang RT, Barthelemy F, Martin AS, Douine ED, Eskin A, Lucas A, Lavigne J, Peay H, Khanlou N, Sweeney L, Cantor RM, Miceli MC, Nelson SF. DMD genotype correlations from the Duchenne Registry: Endogenous exon skipping is a factor in prolonged ambulation for individuals with a defined mutation subtype. Hum Mutat 2018; 39:1193-1202. [PMID: 29907980 PMCID: PMC6175390 DOI: 10.1002/humu.23561] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Revised: 05/10/2018] [Accepted: 05/31/2018] [Indexed: 01/05/2023]
Abstract
Antisense oligonucleotide (AON)-mediated exon skipping is an emerging therapeutic for individuals with Duchenne muscular dystrophy (DMD). Skipping of exons adjacent to common exon deletions in DMD using AONs can produce in-frame transcripts and functional protein. Targeted skipping of DMD exons 8, 44, 45, 50, 51, 52, 53, and 55 is predicted to benefit 47% of affected individuals. We observed a correlation between mutation subgroups and age at loss of ambulation in the Duchenne Registry, a large database of phenotypic and genetic data for DMD (N = 765). Males amenable to exon 44 (N = 74) and exon 8 skipping (N = 18) showed prolonged ambulation compared to other exon skip groups and nonsense mutations (P = 0.035 and P < 0.01, respectively). In particular, exon 45 deletions were associated with prolonged age at loss of ambulation relative to the rest of the exon 44 skip amenable cohort and other DMD mutations. Exon 3-7 deletions also showed prolonged ambulation relative to all other exon 8 skippable mutations. Cultured myotubes from DMD patients with deletions of exons 3-7 or exon 45 showed higher endogenous skipping than other mutations, providing a potential biological rationale for our observations. These results highlight the utility of aggregating phenotypic and genotypic data for rare pediatric diseases to reveal progression differences, identify potentially confounding factors, and probe molecular mechanisms that may affect disease severity.
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Affiliation(s)
- Richard T. Wang
- Department of Human GeneticsDavid Geffen School of MedicineUniversity of California ,Los AngelesCalifornia
- Center for Duchenne Muscular DystrophyUniversity of California, Los Angeles,Los AngelesCalifornia
| | - Florian Barthelemy
- Center for Duchenne Muscular DystrophyUniversity of California, Los Angeles,Los AngelesCalifornia
- Department of Microbiology, Immunology, and Molecular Genetics, David Geffen School of Medicine and College of Letters and SciencesUniversity of California, Los Angeles, Los AngelesCalifornia
| | - Ann S. Martin
- Parent Project Muscular DystrophyHackensackNew Jersey
| | - Emilie D. Douine
- Department of Human GeneticsDavid Geffen School of MedicineUniversity of California ,Los AngelesCalifornia
- Center for Duchenne Muscular DystrophyUniversity of California, Los Angeles,Los AngelesCalifornia
| | - Ascia Eskin
- Department of Human GeneticsDavid Geffen School of MedicineUniversity of California ,Los AngelesCalifornia
- Center for Duchenne Muscular DystrophyUniversity of California, Los Angeles,Los AngelesCalifornia
| | - Ann Lucas
- Parent Project Muscular DystrophyHackensackNew Jersey
| | | | - Holly Peay
- Parent Project Muscular DystrophyHackensackNew Jersey
- RTI InternationalResearch Triangle ParkNorth Carolina
| | - Negar Khanlou
- Department of Pathology and Laboratory Medicine, David Geffen School of MedicineUniversity of CaliforniaLos AngelesCalifornia
| | - Lee Sweeney
- Department of Pharmacology and TherapeuticsUniversity of FloridaGainesvilleFlorida
| | - Rita M. Cantor
- Department of Human GeneticsDavid Geffen School of MedicineUniversity of California ,Los AngelesCalifornia
| | - M. Carrie Miceli
- Center for Duchenne Muscular DystrophyUniversity of California, Los Angeles,Los AngelesCalifornia
- Department of Microbiology, Immunology, and Molecular Genetics, David Geffen School of Medicine and College of Letters and SciencesUniversity of California, Los Angeles, Los AngelesCalifornia
- Molecular Biology InstituteUniversity of California, Los AngelesCaliforniaLos Angeles
| | - Stanley F. Nelson
- Department of Human GeneticsDavid Geffen School of MedicineUniversity of California ,Los AngelesCalifornia
- Center for Duchenne Muscular DystrophyUniversity of California, Los Angeles,Los AngelesCalifornia
- Department of Pathology and Laboratory Medicine, David Geffen School of MedicineUniversity of CaliforniaLos AngelesCalifornia
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Clinical Utility Gene Card for: Becker muscular dystrophy. Eur J Hum Genet 2018; 26:1065-1071. [PMID: 29467387 DOI: 10.1038/s41431-017-0064-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Revised: 09/10/2017] [Accepted: 11/23/2017] [Indexed: 12/28/2022] Open
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Carlson CR, Moore SA, Mathews KD. Dystrophinopathy muscle biopsies in the genetic testing ERA: One center's data. Muscle Nerve 2018; 58:10.1002/mus.26083. [PMID: 29365344 PMCID: PMC6057846 DOI: 10.1002/mus.26083] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/22/2018] [Indexed: 12/22/2022]
Abstract
INTRODUCTION Comprehensive genetic testing for dystrophinopathy can detect ∼95% of pathogenic variants in the dystrophin gene (DMD) and is often the preferred diagnostic approach. METHODS We reviewed pathology reports for muscle biopsies evaluated at the University of Iowa with a pathological diagnosis of dystrophinopathy based on dystrophic histopathology and abnormal immunofluorescence staining: reduced to absent dystrophin, expression of utrophin, and loss of neuronal nitric oxide synthase. RESULTS The percentage of muscle biopsies with dystrophinopathy has been stable since 1997. Among 2,298 biopsies evaluated between 2011 and 2016, 72 (3.1%) had pathologic features of dystrophinopathy. Median age at biopsy was 8 years (range, 0.66-84). Half had undergone DMD genetic testing prior to biopsy. Clinical phenotypes recorded on requisitions were typical of muscular dystrophy for 57 (79%) biopsies. DISCUSSION Muscle biopsy continues to play an important role in the diagnosis of dystrophinopathy, particularly in patients with later symptom onset, comorbidities, or normal DMD genetic testing results. Muscle Nerve, 2018.
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Affiliation(s)
| | - Steven A Moore
- Department of Pathology, University of Iowa Hospitals and Clinics, Iowa City, IA
| | - Katherine D Mathews
- Department of Pediatrics, University of Iowa Children’s Hospital, Iowa City, IA
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25
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Tsuda T, Fitzgerald KK. Dystrophic Cardiomyopathy: Complex Pathobiological Processes to Generate Clinical Phenotype. J Cardiovasc Dev Dis 2017; 4:jcdd4030014. [PMID: 29367543 PMCID: PMC5715712 DOI: 10.3390/jcdd4030014] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Revised: 08/27/2017] [Accepted: 08/30/2017] [Indexed: 02/06/2023] Open
Abstract
Duchenne muscular dystrophy (DMD), Becker muscular dystrophy (BMD), and X-linked dilated cardiomyopathy (XL-DCM) consist of a unique clinical entity, the dystrophinopathies, which are due to variable mutations in the dystrophin gene. Dilated cardiomyopathy (DCM) is a common complication of dystrophinopathies, but the onset, progression, and severity of heart disease differ among these subgroups. Extensive molecular genetic studies have been conducted to assess genotype-phenotype correlation in DMD, BMD, and XL-DCM to understand the underlying mechanisms of these diseases, but the results are not always conclusive, suggesting the involvement of complex multi-layers of pathological processes that generate the final clinical phenotype. Dystrophin protein is a part of dystrophin-glycoprotein complex (DGC) that is localized in skeletal muscles, myocardium, smooth muscles, and neuronal tissues. Diversity of cardiac phenotype in dystrophinopathies suggests multiple layers of pathogenetic mechanisms in forming dystrophic cardiomyopathy. In this review article, we review the complex molecular interactions involving the pathogenesis of dystrophic cardiomyopathy, including primary gene mutations and loss of structural integrity, secondary cellular responses, and certain epigenetic and other factors that modulate gene expressions. Involvement of epigenetic gene regulation appears to lead to specific cardiac phenotypes in dystrophic hearts.
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Affiliation(s)
- Takeshi Tsuda
- Nemours Cardiac Center, Nemours/Alfred I. duPont Hospital for Children, Wilmington, 1600 Rockland Rd, DE 19803, USA.
| | - Kristi K Fitzgerald
- Nemours Cardiac Center, Nemours/Alfred I. duPont Hospital for Children, Wilmington, 1600 Rockland Rd, DE 19803, USA.
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Zimowski JG, Pawelec M, Purzycka JK, Szirkowiec W, Zaremba J. Deletions, not duplications or small mutations, are the predominante new mutations in the dystrophin gene. J Hum Genet 2017; 62:885-888. [PMID: 28680110 DOI: 10.1038/jhg.2017.70] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Revised: 04/20/2017] [Accepted: 05/26/2017] [Indexed: 01/15/2023]
Abstract
Examination of the carrier state was performed in 744 unrelated mothers of the Duchenne muscular dystrophy/Becker muscular dystrophy (DMD/BMD) probands with identified mutations in the dystrophin gene. Owing to that it was possible to assess frequency and type of new mutations in the gene. Contrary to the Japanese observations of Lee et al. published in this journal, we did not find significant differences in the carrier frequency between mothers of DMD and BMD patients. However, we found that new mutations in patients with deletions were significantly more frequent than in those with duplications and small mutations: of 564 unrelated patients with deletions, 236 (41.8%) carried new mutations, the respective values for duplications and small mutations were 21 of 95 patients (22.1%) and 18 of 85 patients (21.2%)-the differences highly significant (P<0.0001).
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Affiliation(s)
- Janusz G Zimowski
- Department of Genetics, Institute of Psychiatry and Neurology, Warsaw, Poland
| | - Magdalena Pawelec
- Department of Genetics, Institute of Psychiatry and Neurology, Warsaw, Poland
| | - Joanna K Purzycka
- Department of Genetics, Institute of Psychiatry and Neurology, Warsaw, Poland
| | | | - Jacek Zaremba
- Department of Genetics, Institute of Psychiatry and Neurology, Warsaw, Poland
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27
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Wang L, Chen M, He R, Sun Y, Yang J, Xiao L, Cao J, Zhang H, Zhang C. Serum Creatinine Distinguishes Duchenne Muscular Dystrophy from Becker Muscular Dystrophy in Patients Aged ≤3 Years: A Retrospective Study. Front Neurol 2017; 8:196. [PMID: 28533764 PMCID: PMC5421192 DOI: 10.3389/fneur.2017.00196] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Accepted: 04/21/2017] [Indexed: 11/13/2022] Open
Abstract
Here, we investigated correlations between serum creatinine (SCRN) levels and clinical phenotypes of dystrophinopathy in young patients. Sixty-eight patients with dystrophinopathy at the Neuromuscular Clinic, The First Affiliated Hospital, Sun Yat-sen University, were selected for this study. The diagnosis of dystrophinopathy was based on clinical manifestation, biochemical changes, and molecular analysis. Some patients underwent muscle biopsies; SCRN levels were tested when patients were ≤3 years old, and reading frame changes were analyzed. Each patient was followed up, and motor function and clinical phenotype were assessed when the same patients were ≥4 years old. Our findings indicated that in young patients, lower SCRN levels were associated with increased disease severity (p < 0.01) and that SCRN levels were the highest in patients exhibiting mild Becker muscular dystrophy (BMD) (p < 0.001) and the lowest in patients with Duchenne muscular dystrophy (DMD) (p < 0.01) and were significantly higher in patients carrying in-frame mutations than in patients carrying out-of-frame mutations (p < 0.001). SCRN level cutoff values for identifying mild BMD [18 µmol/L; area under the curve (AUC): 0.947; p < 0.001] and DMD (17 µmol/L; AUC: 0.837; p < 0.001) were established. These results suggest that SCRN might be a valuable biomarker for distinguishing DMD from BMD in patients aged ≤3 years and could assist in the selection of appropriate treatment strategies.
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Affiliation(s)
- Liang Wang
- Department of Neurology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Menglong Chen
- Department of Neurology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Ruojie He
- Department of Neurology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Yiming Sun
- Department of Health Care, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Juan Yang
- Department of Neurology, Zhujiang Hospital, Southern Medical University, Guangzhou, Guangdong, China
| | - Lulu Xiao
- The Department of Tissue Typing Center, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong, China
| | - Jiqing Cao
- Department of Neurology, Wuhan Central Hospital, Wuhan, Hubei, China
| | - Huili Zhang
- Department of Neurology, Guangzhou First People's Hospital, Guangzhou, Guangdong, China
| | - Cheng Zhang
- Department of Neurology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China
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28
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29
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Bello L, Campadello P, Barp A, Fanin M, Semplicini C, Sorarù G, Caumo L, Calore C, Angelini C, Pegoraro E. Functional changes in Becker muscular dystrophy: implications for clinical trials in dystrophinopathies. Sci Rep 2016; 6:32439. [PMID: 27582364 PMCID: PMC5007528 DOI: 10.1038/srep32439] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Accepted: 08/05/2016] [Indexed: 01/16/2023] Open
Abstract
We performed a 1-year longitudinal study of Six Minute Walk Test (6MWT), North Star Ambulatory Assessment (NSAA), and timed function tests in Becker muscular dystrophy (BMD). Skeletal muscle dystrophin was quantified by immunoblot. We grouped deletions ending on exon 45 ("del 45-x", n = 28) or 51 ("del x-51", n = 10); isolated exon 48 deletion ("del 48", n = 10); and other mutations (n = 21). Only patients in the "del 45-x" or "other" groups became non-ambulatory (n = 5, log-rank p = n.s.) or unable to run (n = 22, p < 0.001). All measures correlated positively with dystrophin quantity and negatively with age, and were significantly more impaired in the "del 45-x" and "other" groups. After one year, NSAA score decreased significantly (-0.9 ± 1.6, p < 0.001); in the "del 45-x" group, both NSAA (-1.3 ± 1.7, p = 0.001) and 6MWT (-12 ± 31 m, p = 0.059) decreased. We conclude that patients with "del x-51" or "del 48" mutations have mild or asymptomatic BMD, while "del 45-x" mutations cause comparatively severe weakness, and functional deterioration in 1 year. Furthermore, exon 51 skipping could be more effective than exon 45 skipping in Duchenne muscular dystrophy.
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Affiliation(s)
- Luca Bello
- Department of Neurosciences, University of Padova, Padova, Italy
| | - Paola Campadello
- Department of Neurosciences, University of Padova, Padova, Italy
| | - Andrea Barp
- Department of Neurosciences, University of Padova, Padova, Italy
| | - Marina Fanin
- Department of Neurosciences, University of Padova, Padova, Italy
| | | | - Gianni Sorarù
- Department of Neurosciences, University of Padova, Padova, Italy
| | - Luca Caumo
- Department of Neurosciences, University of Padova, Padova, Italy
| | - Chiara Calore
- Department of Cardiac, Thoracic and Vascular Sciences, Cardiology Clinic, University of Padova, Padova, Italy
| | - Corrado Angelini
- Department of Neurosciences, University of Padova, Padova, Italy
| | - Elena Pegoraro
- Department of Neurosciences, University of Padova, Padova, Italy
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30
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Brinkmeyer-Langford C, Balog-Alvarez C, Cai JJ, Davis BW, Kornegay JN. Genome-wide association study to identify potential genetic modifiers in a canine model for Duchenne muscular dystrophy. BMC Genomics 2016; 17:665. [PMID: 27549615 PMCID: PMC4994242 DOI: 10.1186/s12864-016-2948-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Accepted: 07/18/2016] [Indexed: 12/17/2022] Open
Abstract
Background Duchenne muscular dystrophy (DMD) causes progressive muscle degeneration, cardiomyopathy and respiratory failure in approximately 1/5,000 boys. Golden Retriever muscular dystrophy (GRMD) resembles DMD both clinically and pathologically. Like DMD, GRMD exhibits remarkable phenotypic variation among affected dogs, suggesting the influence of modifiers. Understanding the role(s) of genetic modifiers of GRMD may identify genes and pathways that also modify phenotypes in DMD and reveal novel therapies. Therefore, our objective in this study was to identify genetic modifiers that affect discrete GRMD phenotypes. Results We performed a linear mixed-model (LMM) analysis using 16 variably-affected dogs from our GRMD colony (8 dystrophic, 8 non-dystrophic). All of these dogs were either full or half-siblings, and phenotyped for 19 objective, quantitative biomarkers at ages 6 and 12 months. Each biomarker was individually assessed. Gene expression profiles of 59 possible candidate genes were generated for two muscle types: the cranial tibialis and medial head of the gastrocnemius. SNPs significantly associated with GRMD biomarkers were identified on multiple chromosomes (including the X chromosome). Gene expression levels for candidate genes located near these SNPs correlated with biomarker values, suggesting possible roles as GRMD modifiers. Conclusions The results of this study enhance our understanding of GRMD pathology and represent a first step toward the characterization of GRMD modifiers that may be relevant to DMD pathology. Such modifiers are likely to be useful for DMD treatment development based on their relationships to GRMD phenotypes. Electronic supplementary material The online version of this article (doi:10.1186/s12864-016-2948-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | - Cynthia Balog-Alvarez
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas, USA
| | - James J Cai
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas, USA
| | - Brian W Davis
- Cancer Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
| | - Joe N Kornegay
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas, USA
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31
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Punetha J, Mansoor S, Bertorini TE, Kesari A, Brown KJ, Hoffman EP. Somatic mosaicism due to a reversion variant causing hemi-atrophy: a novel variant of dystrophinopathy. Eur J Hum Genet 2016; 24:1511-4. [PMID: 26956251 DOI: 10.1038/ejhg.2016.22] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2015] [Revised: 02/04/2016] [Accepted: 02/10/2016] [Indexed: 11/09/2022] Open
Abstract
We describe a case of hemi-atrophy in a young adult male, with a positive family history of three maternal uncles with Duchenne muscular dystrophy (DMD). The patient showed progressive weakness localized to the left side, an abnormal electromyography, and creatine kinase levels >3000 IU/l. Muscle biopsy showed both dystrophin-positive and -negative myofibers. An out-of-frame duplication variant in DMD, that is, c.(93+1_94-1)_(649+1_650-1)dup(p.?) resulting in duplication of exons 3-7 was inherited, but the muscle biopsy showed dystrophin mRNA with and without the duplication. Dystrophin quantification using mass spectrometry showed 25% normal dystrophin protein levels in the muscle biopsy from the stronger right side. Sex chromosome aneuploidy was ruled out. We conclude that the patient inherited the duplication variant, but early in development an inner cell mass underwent a somatic recombination event removing the duplication and restoring dystrophin expression. To our knowledge, this is the first report of a reversion leading to somatic mosaicism in DMD.
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Affiliation(s)
- Jaya Punetha
- Department of Integrative Systems Biology, The George Washington University School of Medicine, Washington, DC, USA.,Research Center for Genetic Medicine, Children's National Medical Center, Washington, DC, USA
| | - Simin Mansoor
- Department of Neurology, The University of Tennessee Health Science Center, Memphis, TN, USA
| | - Tulio E Bertorini
- Department of Neurology, The University of Tennessee Health Science Center, Memphis, TN, USA
| | - Akanchha Kesari
- Research Center for Genetic Medicine, Children's National Medical Center, Washington, DC, USA
| | - Kristy J Brown
- Research Center for Genetic Medicine, Children's National Medical Center, Washington, DC, USA
| | - Eric P Hoffman
- Department of Integrative Systems Biology, The George Washington University School of Medicine, Washington, DC, USA.,Research Center for Genetic Medicine, Children's National Medical Center, Washington, DC, USA
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32
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Fiorillo AA, Heier CR, Novak JS, Tully CB, Brown KJ, Uaesoontrachoon K, Vila MC, Ngheim PP, Bello L, Kornegay JN, Angelini C, Partridge TA, Nagaraju K, Hoffman EP. TNF-α-Induced microRNAs Control Dystrophin Expression in Becker Muscular Dystrophy. Cell Rep 2015; 12:1678-90. [PMID: 26321630 DOI: 10.1016/j.celrep.2015.07.066] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Revised: 06/28/2015] [Accepted: 07/29/2015] [Indexed: 12/22/2022] Open
Abstract
The amount and distribution of dystrophin protein in myofibers and muscle is highly variable in Becker muscular dystrophy and in exon-skipping trials for Duchenne muscular dystrophy. Here, we investigate a molecular basis for this variability. In muscle from Becker patients sharing the same exon 45-47 in-frame deletion, dystrophin levels negatively correlate with microRNAs predicted to target dystrophin. Seven microRNAs inhibit dystrophin expression in vitro, and three are validated in vivo (miR-146b/miR-374a/miR-31). microRNAs are expressed in dystrophic myofibers and increase with age and disease severity. In exon-skipping-treated mdx mice, microRNAs are significantly higher in muscles with low dystrophin rescue. TNF-α increases microRNA levels in vitro whereas NFκB inhibition blocks this in vitro and in vivo. Collectively, these data show that microRNAs contribute to variable dystrophin levels in muscular dystrophy. Our findings suggest a model where chronic inflammation in distinct microenvironments induces pathological microRNAs, initiating a self-sustaining feedback loop that exacerbates disease progression.
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Affiliation(s)
- Alyson A Fiorillo
- Center for Genetic Medicine Research, Children's National Medical Center, Washington, DC 20010, USA
| | - Christopher R Heier
- Center for Genetic Medicine Research, Children's National Medical Center, Washington, DC 20010, USA
| | - James S Novak
- Center for Genetic Medicine Research, Children's National Medical Center, Washington, DC 20010, USA
| | - Christopher B Tully
- Center for Genetic Medicine Research, Children's National Medical Center, Washington, DC 20010, USA
| | - Kristy J Brown
- Center for Genetic Medicine Research, Children's National Medical Center, Washington, DC 20010, USA; Department of Integrative Systems Biology, George Washington University School of Medicine and Health Sciences, Washington, DC 20010, USA
| | - Kitipong Uaesoontrachoon
- Center for Genetic Medicine Research, Children's National Medical Center, Washington, DC 20010, USA
| | - Maria C Vila
- Center for Genetic Medicine Research, Children's National Medical Center, Washington, DC 20010, USA
| | - Peter P Ngheim
- Center for Genetic Medicine Research, Children's National Medical Center, Washington, DC 20010, USA
| | - Luca Bello
- Center for Genetic Medicine Research, Children's National Medical Center, Washington, DC 20010, USA; Fondazione Ospedale S. Camillo, IRCCS, Lido Venice 30126, Italy
| | - Joe N Kornegay
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX 77845, USA
| | | | - Terence A Partridge
- Center for Genetic Medicine Research, Children's National Medical Center, Washington, DC 20010, USA; Department of Integrative Systems Biology, George Washington University School of Medicine and Health Sciences, Washington, DC 20010, USA
| | - Kanneboyina Nagaraju
- Center for Genetic Medicine Research, Children's National Medical Center, Washington, DC 20010, USA; Department of Integrative Systems Biology, George Washington University School of Medicine and Health Sciences, Washington, DC 20010, USA
| | - Eric P Hoffman
- Center for Genetic Medicine Research, Children's National Medical Center, Washington, DC 20010, USA; Department of Integrative Systems Biology, George Washington University School of Medicine and Health Sciences, Washington, DC 20010, USA.
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33
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Liang Y, Chen S, Zhu J, Zhou X, Yang C, Yao L, Zhang C. Dystrophin hydrophobic regions in the pathogenesis of Duchenne and Becker muscular dystrophies. Bosn J Basic Med Sci 2015; 15:42-9. [PMID: 26042512 DOI: 10.17305/bjbms.2015.300] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2015] [Revised: 03/03/2015] [Accepted: 03/04/2015] [Indexed: 01/16/2023] Open
Abstract
The aim of our study was to determine the role of dystrophin hydrophobic regions in the pathogenesis of Duchenne (DMD) and Becker (BMD) muscular dystrophies, by the Kyte-Doolittle scale mean hydrophobicity profile and 3D molecular models. A total of 1038 cases diagnosed with DMD or BMD with the in-frame mutation were collected in our hospital and the Leiden DMD information database in the period 2002-2013. Correlation between clinical types and genotypes were determined on the basis of these two sources. In addition, the Kyte-Doolittle scale mean hydrophobicity of dystrophin was analyzed using BioEdit software and the models of the hydrophobic domains of dystrophin were constructed. The presence of four hydrophobic regions is confirmed. They include the calponin homology CH2 domain on the actin-binding domain (ABD), spectrin-type repeat 16, hinge III and the EF Hand domain. The severe symptoms of DMD usually develop as a result of the mutational disruption in the hydrophobic regions I, II and IV of dystrophin - those that bind associated proteins of the dystrophin-glycoprotein complex (DGC). On the other hand, when the hydrophobic region III is deleted, the connection of the ordered repeat domains of the central rod domain remains intact, resulting in the less severe clinical presentation. We conclude that mutational changes in the structure of hydrophobic regions of dystrophin play an important role in the pathogenesis of DMD.
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Affiliation(s)
- Yingyin Liang
- Department of Neurology, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong Province.
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Li W, Zheng Y, Zhang W, Wang Z, Xiao J, Yuan Y. Progression and variation of fatty infiltration of the thigh muscles in Duchenne muscular dystrophy, a muscle magnetic resonance imaging study. Neuromuscul Disord 2015; 25:375-80. [DOI: 10.1016/j.nmd.2015.01.003] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2014] [Revised: 01/11/2015] [Accepted: 01/14/2015] [Indexed: 02/04/2023]
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35
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Greer K, Mizzi K, Rice E, Kuster L, Barrero RA, Bellgard MI, Lynch BJ, Foley AR, O Rathallaigh E, Wilton SD, Fletcher S. Pseudoexon activation increases phenotype severity in a Becker muscular dystrophy patient. Mol Genet Genomic Med 2015; 3:320-6. [PMID: 26247048 PMCID: PMC4521967 DOI: 10.1002/mgg3.144] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Revised: 03/13/2015] [Accepted: 03/16/2015] [Indexed: 01/16/2023] Open
Abstract
We report a dystrophinopathy patient with an in-frame deletion of DMD exons 45-47, and therefore a genetic diagnosis of Becker muscular dystrophy, who presented with a more severe than expected phenotype. Analysis of the patient DMD mRNA revealed an 82 bp pseudoexon, derived from intron 44, that disrupts the reading frame and is expected to yield a nonfunctional dystrophin. Since the sequence of the pseudoexon and canonical splice sites does not differ from the reference sequence, we concluded that the genomic rearrangement promoted recognition of the pseudoexon, causing a severe dystrophic phenotype. We characterized the deletion breakpoints and identified motifs that might influence selection of the pseudoexon. We concluded that the donor splice site was strengthened by juxtaposition of intron 47, and loss of intron 44 silencer elements, normally located downstream of the pseudoexon donor splice site, further enhanced pseudoexon selection and inclusion in the DMD transcript in this patient.
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Affiliation(s)
- Kane Greer
- Centre for Comparative Genomics, Murdoch University 90 South St, Murdoch, Western Australia, 6150, Australia ; The University of Western Australia 35 Stirling Highway, Crawley, Western Australia, 6009, Australia
| | - Kayla Mizzi
- The University of Western Australia 35 Stirling Highway, Crawley, Western Australia, 6009, Australia
| | - Emily Rice
- The University of Western Australia 35 Stirling Highway, Crawley, Western Australia, 6009, Australia
| | - Lukas Kuster
- The University of Western Australia 35 Stirling Highway, Crawley, Western Australia, 6009, Australia
| | - Roberto A Barrero
- Centre for Comparative Genomics, Murdoch University 90 South St, Murdoch, Western Australia, 6150, Australia
| | - Matthew I Bellgard
- Centre for Comparative Genomics, Murdoch University 90 South St, Murdoch, Western Australia, 6150, Australia
| | - Bryan J Lynch
- Children's University Hospital Temple Street, Dublin, Ireland
| | | | | | - Steve D Wilton
- Centre for Comparative Genomics, Murdoch University 90 South St, Murdoch, Western Australia, 6150, Australia ; The University of Western Australia 35 Stirling Highway, Crawley, Western Australia, 6009, Australia ; Western Australian Neuroscience Institute Nedlands, Western Australia, 6009, Australia
| | - Sue Fletcher
- Centre for Comparative Genomics, Murdoch University 90 South St, Murdoch, Western Australia, 6150, Australia ; The University of Western Australia 35 Stirling Highway, Crawley, Western Australia, 6009, Australia ; Western Australian Neuroscience Institute Nedlands, Western Australia, 6009, Australia
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Early-progressive dilated cardiomyopathy in a family with Becker muscular dystrophy related to a novel frameshift mutation in the dystrophin gene exon 27. J Hum Genet 2014; 60:151-5. [PMID: 25537791 PMCID: PMC4374993 DOI: 10.1038/jhg.2014.112] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Revised: 11/25/2014] [Accepted: 11/27/2014] [Indexed: 01/16/2023]
Abstract
We report a family in which two male siblings with Becker muscular dystrophy (BMD) developed severe dilated cardiomyopathy (DCM) and progressive heart failure (HF) at age 11; one died at age 14 years while awaiting heart transplant and the other underwent left ventricular assist device (LVAD) implantation at the same age. Genetic analysis of one sibling showed a novel frameshift mutation in exon 27 of Duchenne muscular dystrophy (DMD) gene (c.3779_3785delCTTTGGAins GG), in which 7 base pairs are deleted and two are inserted. While this predicts an amino acid substitution and premature termination (p.Thr1260Argfs*8), muscle biopsy dystrophin immunostaining instead indicates that the mutation is more likely to alter splicing. Despite relatively preserved skeletal muscular performance, both siblings developed progressive heart failure secondary to early onset DCM. In addition, their 7 year old nephew with delayed gross motor development, mild proximal muscle weakness, and markedly elevated serum creatine kinase (CK) level (> 13,000 IU/L) at 16 months was recently demonstrated to have the familial DMD mutation. Here we report a novel genotype of BMD with early onset DCM and progressive lethal heart failure during early adolescence.
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MLPA based detection of mutations in the dystrophin gene of 180 Polish families with Duchenne/Becker muscular dystrophy. Neurol Neurochir Pol 2014; 48:416-22. [DOI: 10.1016/j.pjnns.2014.10.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Revised: 10/03/2014] [Accepted: 10/15/2014] [Indexed: 11/17/2022]
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Zatz M, Pavanello R, Lazar M, Yamamoto G, Lourenço N, Cerqueira A, Nogueira L, Vainzof M. Milder course in Duchenne patients with nonsense mutations and no muscle dystrophin. Neuromuscul Disord 2014; 24:986-9. [DOI: 10.1016/j.nmd.2014.06.003] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Accepted: 06/01/2014] [Indexed: 11/25/2022]
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New variants, challenges and pitfalls in DMD genotyping: implications in diagnosis, prognosis and therapy. J Hum Genet 2014; 59:454-64. [DOI: 10.1038/jhg.2014.54] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Revised: 06/02/2014] [Accepted: 06/06/2014] [Indexed: 01/17/2023]
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A novel splicing silencer generated by DMD exon 45 deletion junction could explain upstream exon 44 skipping that modifies dystrophinopathy. J Hum Genet 2014; 59:423-9. [PMID: 24871807 DOI: 10.1038/jhg.2014.36] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Revised: 03/30/2014] [Accepted: 04/18/2014] [Indexed: 12/22/2022]
Abstract
Duchenne muscular dystrophy (DMD), a progressive muscle-wasting disease, is mostly caused by exon deletion mutations in the DMD gene. The reading frame rule explains that out-of-frame deletions lead to muscle dystrophin deficiency in DMD. In outliers to this rule, deletion junction sequences have never previously been explored as splicing modulators. In a Japanese case, we identified a single exon 45 deletion in the patient's DMD gene, indicating out-of-frame mutation. However, immunohistochemical examination disclosed weak dystrophin signals in his muscle. Reverse transcription-PCR amplification of DMD exons 42 to 47 revealed a major normally spliced product with exon 45 deletion and an additional in-frame product with deletion of both exons 44 and 45, indicating upstream exon 44 skipping. We considered the latter to underlie the observed dystrophin expression. Remarkably, the junction sequence cloned by PCR walking abolished the splicing enhancer activity of the upstream intron in a chimeric doublesex gene pre-mRNA in vitro splicing. Furthermore, antisense oligonucleotides directed against the junction site counteracted this effect. These indicated that the junction sequence was a splicing silencer that induced upstream exon 44 skipping. It was strongly suggested that creation of splicing regulator is a modifier of dystrophinopathy.
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Brinkmeyer-Langford C, Kornegay JN. Comparative Genomics of X-linked Muscular Dystrophies: The Golden Retriever Model. Curr Genomics 2014; 14:330-42. [PMID: 24403852 PMCID: PMC3763684 DOI: 10.2174/13892029113149990004] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Revised: 07/16/2013] [Accepted: 07/19/2013] [Indexed: 12/30/2022] Open
Abstract
Duchenne muscular dystrophy (DMD) is a devastating disease that dramatically decreases the lifespan and abilities of affected young people. The primary molecular cause of the disease is the absence of functional dystrophin protein, which is critical to proper muscle function. Those with DMD vary in disease presentation and dystrophin mutation; the same causal mutation may be associated with drastically different levels of disease severity. Also contributing to this variation are the influences of additional modifying genes and/or changes in functional elements governing such modifiers. This genetic heterogeneity complicates the efficacy of treatment methods and to date medical interventions are limited to treating symptoms. Animal models of DMD have been instrumental in teasing out the intricacies of DMD disease and hold great promise for advancing knowledge of its variable presentation and treatment. This review addresses the utility of comparative genomics in elucidating the complex background behind phenotypic variation in a canine model of DMD, Golden Retriever muscular dystrophy (GRMD). This knowledge can be exploited in the development of improved, more personalized treatments for DMD patients, such as therapies that can be tailor-matched to the disease course and genomic background of individual patients.
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Affiliation(s)
- Candice Brinkmeyer-Langford
- Texas A&M University College of Veterinary Medicine, Dept. of Veterinary Integrative Biosciences - Mailstop 4458, College Station, Texas, U.S.A. 77843-4458
| | - Joe N Kornegay
- Texas A&M University College of Veterinary Medicine, Dept. of Veterinary Integrative Biosciences - Mailstop 4458, College Station, Texas, U.S.A. 77843-4458
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Pane M, Mazzone ES, Sormani MP, Messina S, Vita GL, Fanelli L, Berardinelli A, Torrente Y, D'Amico A, Lanzillotta V, Viggiano E, D'Ambrosio P, Cavallaro F, Frosini S, Bello L, Bonfiglio S, Scalise R, De Sanctis R, Rolle E, Bianco F, Van der Haawue M, Magri F, Palermo C, Rossi F, Donati MA, Alfonsi C, Sacchini M, Arnoldi MT, Baranello G, Mongini T, Pini A, Battini R, Pegoraro E, Previtali SC, Napolitano S, Bruno C, Politano L, Comi GP, Bertini E, Morandi L, Gualandi F, Ferlini A, Goemans N, Mercuri E. 6 Minute walk test in Duchenne MD patients with different mutations: 12 month changes. PLoS One 2014; 9:e83400. [PMID: 24421885 PMCID: PMC3885414 DOI: 10.1371/journal.pone.0083400] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2013] [Accepted: 11/13/2013] [Indexed: 01/10/2023] Open
Abstract
OBJECTIVE In the last few years some of the therapeutical approaches for Duchenne muscular dystrophy (DMD) are specifically targeting distinct groups of mutations, such as deletions eligible for skipping of individual exons. The aim of this observational study was to establish whether patients with distinct groups of mutations have different profiles of changes on the 6 minute walk test (6MWT) over a 12 month period. METHODS The 6MWT was performed in 191 ambulant DMD boys at baseline and 12 months later. The results were analysed using a test for heterogeneity in order to establish possible differences among different types of mutations (deletions, duplications, point mutations) and among subgroups of deletions eligible to skip individual exons. RESULTS At baseline the 6MWD ranged between 180 and 560,80 metres (mean 378,06, SD 74,13). The 12 month changes ranged between -325 and 175 (mean -10.8 meters, SD 69.2). Although boys with duplications had better results than those with the other types of mutations, the difference was not significant. Similarly, boys eligible for skipping of the exon 44 had better baseline results and less drastic changes than those eligible for skipping exon 45 or 53, but the difference was not significant. CONCLUSIONS even if there are some differences among subgroups, the mean 12 month changes in each subgroup were all within a narrow Range: from the mean of the whole DMD cohort. This information will be of help at the time of designing clinical trials with small numbers of eligible patients.
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Affiliation(s)
- Marika Pane
- Department of Paediatric Neurology, Catholic University, Rome, Italy
| | - Elena S. Mazzone
- Department of Paediatric Neurology, Catholic University, Rome, Italy
| | - Maria Pia Sormani
- Biostatistics Unit, Department of Health Sciences, University of Genoa, Italy
| | - Sonia Messina
- Department of Neurosciences, Psychiatry and Anaesthesiology, University of Messina, Messina, Italy
| | - Gian Luca Vita
- Department of Neurosciences, Psychiatry and Anaesthesiology, University of Messina, Messina, Italy
| | - Lavinia Fanelli
- Department of Paediatric Neurology, Catholic University, Rome, Italy
| | | | - Yvan Torrente
- Dino Ferrari Centre, Neuroscience Section, Department of Pathophysiology and Transplantation (DEPT), University of Milan, Neurology Unit, Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Adele D'Amico
- Unit of Neuromuscular and Neurodegenerative Diseases, Department of Neurosciences, Bambino Gesù Children's Hospital, Rome, Italy
| | | | - Emanuela Viggiano
- Dipartimento di Medicina Sperimentale, Seconda Università di Napoli, Napoli, Italy
| | - Paola D'Ambrosio
- Dipartimento di Medicina Sperimentale, Seconda Università di Napoli, Napoli, Italy
| | - Filippo Cavallaro
- Department of Neurosciences, Psychiatry and Anaesthesiology, University of Messina, Messina, Italy
| | - Silvia Frosini
- Department of Developmental Neuroscience, Stella Maris Institute, University of Pisa, Pisa, Italy
| | - Luca Bello
- Department of Neurosciences, University of Padua, Padua, Italy
| | - Serena Bonfiglio
- Child Neurology and Psychiatry Unit, IRCCS Istituto delle Scienze Neurologiche, Bologna, Italy
| | - Roberta Scalise
- Department of Paediatric Neurology, Catholic University, Rome, Italy
| | | | - Enrica Rolle
- Neuromuscular Center, SG. Battista Hospital, University of Turin, Turin, Italy
| | - Flaviana Bianco
- Department of Paediatric Neurology, Catholic University, Rome, Italy
| | | | - Francesca Magri
- Dino Ferrari Centre, Neuroscience Section, Department of Pathophysiology and Transplantation (DEPT), University of Milan, Neurology Unit, Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Concetta Palermo
- Department of Paediatric Neurology, Catholic University, Rome, Italy
| | | | | | - Chiara Alfonsi
- Department of Paediatric Neurology, Catholic University, Rome, Italy
| | - Michele Sacchini
- Metabolic and Neuromuscular Unit, Meyer Hospital, Florence, Italy
| | | | - Giovanni Baranello
- Developmental Neurology Unit, Istituto Neurologico “Besta”, Milan, Italy
| | - Tiziana Mongini
- Neuromuscular Center, SG. Battista Hospital, University of Turin, Turin, Italy
| | - Antonella Pini
- Child Neurology and Psychiatry Unit, IRCCS Istituto delle Scienze Neurologiche, Bologna, Italy
| | - Roberta Battini
- Department of Developmental Neuroscience, Stella Maris Institute, University of Pisa, Pisa, Italy
| | - Elena Pegoraro
- Department of Neurosciences, University of Padua, Padua, Italy
| | | | - Sara Napolitano
- Department of Neurology, San Raffaele Scientific Institute, Milan, Italy
| | - Claudio Bruno
- Neuromuscular Disease Unit, G. Gaslini Institute, Genoa, Italy
| | - Luisa Politano
- Dipartimento di Medicina Sperimentale, Seconda Università di Napoli, Napoli, Italy
| | - Giacomo P. Comi
- Dino Ferrari Centre, Neuroscience Section, Department of Pathophysiology and Transplantation (DEPT), University of Milan, Neurology Unit, Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Enrico Bertini
- Unit of Neuromuscular and Neurodegenerative Diseases, Department of Neurosciences, Bambino Gesù Children's Hospital, Rome, Italy
| | - Lucia Morandi
- Neuromuscular Disease and Immunology Unit, Istituto Neurologico “Besta”, Milan, Italy
| | - Francesca Gualandi
- Section of Medical Genetics, Department of Experimental and Diagnostic Medicine, University of Ferrara, Ferrara, Italy
| | - Alessandra Ferlini
- Section of Medical Genetics, Department of Experimental and Diagnostic Medicine, University of Ferrara, Ferrara, Italy
| | | | - Eugenio Mercuri
- Department of Paediatric Neurology, Catholic University, Rome, Italy
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Jarmin S, Kymalainen H, Popplewell L, Dickson G. New developments in the use of gene therapy to treat Duchenne muscular dystrophy. Expert Opin Biol Ther 2013; 14:209-30. [PMID: 24308293 DOI: 10.1517/14712598.2014.866087] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
INTRODUCTION Duchenne muscular dystrophy (DMD) is a lethal X-linked inherited disorder characterised by progressive muscle weakness, wasting and degeneration. Although the gene affected in DMD was identified over 25 years ago, there is still no effective treatment. AREAS COVERED Here we review some of the genetic-based strategies aimed at amelioration of the DMD phenotype. A number of Phase II/III clinical trials of antisense oligonucleotide-induced exon skipping for restoration of the open reading frame (ORF) of the DMD gene have recently been completed. The potential strategies for overcoming the hurdles that appear to prevent exon skipping becoming an effective treatment for DMD currently are discussed. EXPERT OPINION The applicability of exon skipping as a therapy to DMD is restricted and the development of alternative strategies that are more encompassing is needed. The rapid pre-clinical advances that are being made in the field of adeno-associated virus (AAV)-based delivery of micro-dystrophin would address this. The obstacles to be faced with gene replacement strategies would include the need for high viral titres, efficient muscle targeting and avoidance of immune response to vector and transgene. The new emerging field of gene editing could potentially provide permanent correction of the DMD gene and the feasibility of such an approach to DMD is discussed.
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Affiliation(s)
- Susan Jarmin
- Royal Holloway University of London , Egham, Surrey , UK
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Molecular analysis of the dystrophin gene in 407 Chinese patients with Duchenne/Becker muscular dystrophy by the combination of multiplex ligation-dependent probe amplification and Sanger sequencing. Clin Chim Acta 2013; 423:35-8. [PMID: 23588064 DOI: 10.1016/j.cca.2013.04.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Revised: 04/05/2013] [Accepted: 04/06/2013] [Indexed: 11/20/2022]
Abstract
BACKGROUND Progressive muscular dystrophy is a leading neuromuscular disorder without any effective treatments and a common genetic cause of mortality among teenagers. A challenge exists in the screening of subtle mutations in 79 exons and little is known about the genotype-phenotype correlation. METHODS Here we adopted multiplex ligation-dependent probe amplification and Sanger sequencing to detect the dystrophin gene in 407 patients and 76 mothers. RESULTS Sixty-three percent (257/407) of the patients harbored a deletion or duplication mutation, with a de novo mutation frequency of 39.5% in 76 affected patients, and approximately 43.7% of the deletions occurred from exon 45 to 52. To those patients suspected with single exon deletion, combined with Sanger sequencing, five subtle mutations were identified: c.8608C>T, c.2302C>T, c.7148dupT, c.10855C>T and c.2071-2093del AGGGAACAGATCCTGGTAAAGCA; the last three mutations were novel. Furthermore, after genotype-phenotype analysis, the severity of DMD/BMD was associated with the frame shift mutation but not with the deletion, the duplication or the number of deleted exons. CONCLUSION The majority of patients have a deletion/duplication mutation in the dystrophin gene, with a hot deletion mutation region from exon 45 to 52. Combined with Sanger sequencing, multiplex ligation-dependent probe amplification is capable of detecting part of subtle mutations.
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46
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The medical genetics of dystrophinopathies: Molecular genetic diagnosis and its impact on clinical practice. Neuromuscul Disord 2013; 23:4-14. [DOI: 10.1016/j.nmd.2012.09.002] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2012] [Revised: 08/23/2012] [Accepted: 09/04/2012] [Indexed: 01/01/2023]
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47
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Brandão RD, Tserpelis D, Gómez García E, Blok MJ. Detection of exon skipping events in BRCA1 RNA using MLPA kit P002. Mol Biol Rep 2012; 39:7429-33. [PMID: 22350158 PMCID: PMC3358555 DOI: 10.1007/s11033-012-1575-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2011] [Accepted: 01/30/2012] [Indexed: 11/02/2022]
Abstract
A rapid and easy method to screen for aberrant cDNA would be a very useful diagnostic tool in genetics since a fraction of the DNA variants found affect RNA splicing. The currently used RT-PCR methods require new primer combinations to study each variant that might affect splicing. Since MLPA is routinely used to detect large genomic deletions and successfully detected exon skipping events in Duchenne muscular dystrophy in cDNA, we performed a pilot study to evaluate its value for BRCA1 cDNA. The effect of puromycin, DNase I and two different DNA cleaning protocols were tested in the RNA analysis of lymphocyte cultures. We used two samples from unrelated families with two different BRCA1 exon deletion events, two healthy unrelated controls and six samples from hereditary breast/ovarian cancer syndrome (HBOC) patients without BRCA1/2 mutations. Using RNA treated with DNase I and cleaned in a column system from puromycin-treated fractions, we were able to identify the two BRCA1 deletions. Additional HBOC patients did not show additional splice events. However, we were not able to get reproducible results. Therefore, the cDNA-MLPA technique using kit BRCA1 P002 is in our hands currently not reliable enough for routine RNA analysis and needs further optimization.
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Affiliation(s)
- Rita D Brandão
- Department of Clinical Genetics, Maastricht University Medical Centre, PO Box 616, 6200 MD Maastricht, The Netherlands.
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48
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Bovolenta M, Scotton C, Falzarano MS, Gualandi F, Ferlini A. Rapid, comprehensive analysis of the dystrophin transcript by a custom micro-fluidic exome array. Hum Mutat 2012; 33:572-81. [DOI: 10.1002/humu.22017] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2011] [Accepted: 12/20/2011] [Indexed: 11/08/2022]
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Hoffman EP, Bronson A, Levin AA, Takeda S, Yokota T, Baudy AR, Connor EM. Restoring dystrophin expression in duchenne muscular dystrophy muscle progress in exon skipping and stop codon read through. THE AMERICAN JOURNAL OF PATHOLOGY 2011; 179:12-22. [PMID: 21703390 DOI: 10.1016/j.ajpath.2011.03.050] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2011] [Accepted: 03/21/2011] [Indexed: 01/12/2023]
Abstract
The identification of the Duchenne muscular dystrophy gene and protein in the late 1980s led to high hopes of rapid translation to molecular therapeutics. These hopes were fueled by early reports of delivering new functional genes to dystrophic muscle in mouse models using gene therapy and stem cell transplantation. However, significant barriers have thwarted translation of these approaches to true therapies, including insufficient therapeutic material (eg, cells and viral vectors), challenges in systemic delivery, and immunological hurdles. An alternative approach is to repair the patient's own gene. Two innovative small-molecule approaches have emerged as front-line molecular therapeutics: exon skipping and stop codon read through. Both approaches are in human clinical trials and aim to coax dystrophin protein production from otherwise inactive mutant genes. In the clinically severe dog model of Duchenne muscular dystrophy, the exon-skipping approach recently improved multiple functional outcomes. We discuss the status of these two methods aimed at inducing de novo dystrophin production from mutant genes and review implications for other disorders.
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Affiliation(s)
- Eric P Hoffman
- Research Center for Genetic Medicine, Children’s National Medical Center, 111 Michigan Ave NW, Washington, DC 20010, USA.
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50
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Henderson DM, Belanto JJ, Li B, Heun-Johnson H, Ervasti JM. Internal deletion compromises the stability of dystrophin. Hum Mol Genet 2011; 20:2955-63. [PMID: 21558423 DOI: 10.1093/hmg/ddr199] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Duchenne muscular dystrophy (DMD) is a deadly and common childhood disease caused by mutations that disrupt dystrophin protein expression. Several miniaturized dystrophin/utrophin constructs are utilized for gene therapy, and while these constructs have shown promise in mouse models, the functional integrity of these proteins is not well described. Here, we compare the biophysical properties of full-length dystrophin and utrophin with therapeutically relevant miniaturized constructs using an insect cell expression system. Full-length utrophin, like dystrophin, displayed a highly cooperative melting transition well above 37°C. Utrophin constructs involving N-terminal, C-terminal or internal deletions were remarkably stable, showing cooperative melting transitions identical to full-length utrophin. In contrast, large dystrophin deletions from either the N- or C-terminus exhibited variable stability, as evidenced by melting transitions that differed by 20°C. Most importantly, deletions in the large central rod domain of dystrophin resulted in a loss of cooperative unfolding with increased propensity for aggregation. Our results suggest that the functionality of dystrophin therapeutics based on mini- or micro-constructs may be compromised by the presence of non-native protein junctions that result in protein misfolding, instability and aggregation.
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Affiliation(s)
- Davin M Henderson
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
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