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Shelton GD, Minor KM, Friedenberg SG, Cullen JN, Guo LT, Mickelson JR. Current Classification of Canine Muscular Dystrophies and Identification of New Variants. Genes (Basel) 2023; 14:1557. [PMID: 37628610 PMCID: PMC10454810 DOI: 10.3390/genes14081557] [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] [Received: 06/27/2023] [Revised: 07/21/2023] [Accepted: 07/27/2023] [Indexed: 08/27/2023] Open
Abstract
The spectrum of canine muscular dystrophies has rapidly grown with the recent identification of several more affected breeds and associated mutations. Defects include those in genes and protein products associated with the sarcolemma (dystrophin deficient X-linked muscular dystrophy and sarcoglycan-deficient limb-girdle muscular dystrophy) and with the extracellular matrix (collagen 6, laminin α2, and α-dystroglycan-deficient congenital muscular dystrophies). With the increasing application of whole genome sequencing and whole exome sequencing, the clinical and pathological spectra associated with specific neuromuscular genetic defects are constantly evolving. In this report, we provide a brief overview of the current status of gene defects reported in canine muscular dystrophies. We also report the causative mutations for novel forms of X-linked muscular dystrophy in Brittany spaniels and in a French bulldog.
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Affiliation(s)
- G. Diane Shelton
- Department of Pathology, School of Medicine, University of California San Diego, La Jolla, CA 92093, USA;
| | - Katie M. Minor
- Department of Veterinary and Biomedical Sciences, College of Veterinary Medicine, University of Minnesota, Saint Paul, MN 55108, USA; (K.M.M.); (J.R.M.)
| | - Steven G. Friedenberg
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, University of Minnesota, Saint Paul, MN 55108, USA; (S.G.F.); (J.N.C.)
| | - Jonah N. Cullen
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, University of Minnesota, Saint Paul, MN 55108, USA; (S.G.F.); (J.N.C.)
| | - Ling T. Guo
- Department of Pathology, School of Medicine, University of California San Diego, La Jolla, CA 92093, USA;
| | - James R. Mickelson
- Department of Veterinary and Biomedical Sciences, College of Veterinary Medicine, University of Minnesota, Saint Paul, MN 55108, USA; (K.M.M.); (J.R.M.)
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2
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Chey YCJ, Arudkumar J, Aartsma-Rus A, Adikusuma F, Thomas PQ. CRISPR applications for Duchenne muscular dystrophy: From animal models to potential therapies. WIREs Mech Dis 2023; 15:e1580. [PMID: 35909075 PMCID: PMC10078488 DOI: 10.1002/wsbm.1580] [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: 02/02/2022] [Revised: 04/28/2022] [Accepted: 06/30/2022] [Indexed: 01/31/2023]
Abstract
CRISPR gene-editing technology creates precise and permanent modifications to DNA. It has significantly advanced our ability to generate animal disease models for use in biomedical research and also has potential to revolutionize the treatment of genetic disorders. Duchenne muscular dystrophy (DMD) is a monogenic muscle-wasting disease that could potentially benefit from the development of CRISPR therapy. It is commonly associated with mutations that disrupt the reading frame of the DMD gene that encodes dystrophin, an essential scaffolding protein that stabilizes striated muscles and protects them from contractile-induced damage. CRISPR enables the rapid generation of various animal models harboring mutations that closely simulates the wide variety of mutations observed in DMD patients. These models provide a platform for the testing of sequence-specific interventions like CRISPR therapy that aim to reframe or skip DMD mutations to restore functional dystrophin expression. This article is categorized under: Congenital Diseases > Genetics/Genomics/Epigenetics.
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Affiliation(s)
- Yu C J Chey
- School of Biomedicine and Robinson Research Institute, University of Adelaide, Adelaide, South Australia, Australia.,Genome Editing Program, South Australian Health and Medical Research Institute (SAHMRI), Adelaide, South Australia, Australia
| | - Jayshen Arudkumar
- School of Biomedicine and Robinson Research Institute, University of Adelaide, Adelaide, South Australia, Australia.,Genome Editing Program, South Australian Health and Medical Research Institute (SAHMRI), Adelaide, South Australia, Australia
| | - Annemieke Aartsma-Rus
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Fatwa Adikusuma
- School of Biomedicine and Robinson Research Institute, University of Adelaide, Adelaide, South Australia, Australia.,Genome Editing Program, South Australian Health and Medical Research Institute (SAHMRI), Adelaide, South Australia, Australia.,CSIRO Synthetic Biology Future Science Platform, Canberra, Australia
| | - Paul Q Thomas
- School of Biomedicine and Robinson Research Institute, University of Adelaide, Adelaide, South Australia, Australia.,Genome Editing Program, South Australian Health and Medical Research Institute (SAHMRI), Adelaide, South Australia, Australia.,South Australian Genome Editing (SAGE), South Australian Health and Medical Research Institute (SAHMRI), Adelaide, South Australia, Australia
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3
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Sakai K, Motegi T, Chambers JK, Uchida K, Nishida H, Shimamura S, Tani H, Shimada T, Furuya M. Dystrophin-deficient muscular dystrophy in a Toy Poodle with a single base pair insertion in exon 45 of the Duchenne muscular dystrophy gene. J Vet Med Sci 2022; 84:502-506. [PMID: 35135937 PMCID: PMC9096033 DOI: 10.1292/jvms.21-0504] [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] [Indexed: 11/22/2022] Open
Abstract
A 10-month-old, intact male Toy Poodle was referred for a postural abnormality. Blood biochemical tests revealed a marked increase in plasma creatine phosphokinase (CPK) concentration. The isoenzyme test showed that 99% of serum CPK consisted of CPK-MM. Histopathological evaluation of muscle biopsy samples confirmed scattered degeneration and necrosis of myofibers. Immunohistochemistry for dystrophin showed an absence of staining in muscle cells. Based on these findings, the dog was diagnosed with dystrophin-deficient muscular dystrophy. Whole genome sequencing using genomic DNA extracted from blood revealed a single base pair insertion in exon 45 of the Duchenne muscular dystrophy (DMD) gene. This is the first report on muscular dystrophy in Toy Poodles and identified a novel mutation in the DMD gene.
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Affiliation(s)
- Kosei Sakai
- Veterinary Medical Center, Graduate School of Life and Environmental Sciences, Osaka Prefecture University
| | - Tomoki Motegi
- Department of Veterinary Clinical Pathobiology, Graduate School of Agricultural and Life Sciences, The University of Tokyo
| | - James Ken Chambers
- Department of Veterinary Pathology, Graduate School of Agricultural and Life Sciences, The University of Tokyo
| | - Kazuyuki Uchida
- Department of Veterinary Pathology, Graduate School of Agricultural and Life Sciences, The University of Tokyo
| | - Hidetaka Nishida
- Laboratory of Veterinary Surgery, Graduate School of Life and Environmental Sciences, Osaka Prefecture University
| | - Shunsuke Shimamura
- Veterinary Medical Center, Graduate School of Life and Environmental Sciences, Osaka Prefecture University
| | - Hiroyuki Tani
- Laboratory of Veterinary Internal Medicine, Graduate School of Life and Environmental Sciences, Osaka Prefecture University
| | - Terumasa Shimada
- Veterinary Medical Center, Graduate School of Life and Environmental Sciences, Osaka Prefecture University
| | - Masaru Furuya
- Laboratory of Veterinary Internal Medicine, Graduate School of Life and Environmental Sciences, Osaka Prefecture University
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4
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Brands J, Steffen F, Spennes J, Leeb T, Bilzer T. COL6A1 related muscular dystrophy in Landseer dogs: A canine model for Ullrich congenital muscular dystrophy. Muscle Nerve 2021; 63:608-616. [PMID: 33382107 DOI: 10.1002/mus.27162] [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: 03/24/2020] [Revised: 12/27/2020] [Accepted: 12/28/2020] [Indexed: 11/09/2022]
Abstract
BACKGROUND Collagen VI related myopathies are congenital diseases of variable phenotype. The severe phenotype is referred to as Ullrich congenital muscular dystrophy. In this study, we describe analoguos clinical signs and histopathological alterations in Landseer dogs. MATERIALS We collected clinical data from two affected dogs and investigated the neuromuscular changes in five dogs from two different litters with immunohistochemistry and immunofluorescence. All affected dogs were homozygous for the p.Glu97* nonsense variant in the COL6A1 gene encoding the alpha-1 chain of collagen VI. RESULTS Muscle biopsies revealed alterations similar to those in human patients with Ullrich congenital muscular dystrophy including the virtual absence of collagen VI in skeletal muscles. CONCLUSIONS The clinical and pathological characterization of the affected Landseer dogs enhances the value of this animal model for human Ullrich congenital muscular dystrophy.
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Affiliation(s)
- Jan Brands
- Institute of Neuropathology, University Hospital Düsseldorf, Düsseldorf, Germany
| | - Frank Steffen
- Neurology Service, Department of Small Animals, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
| | | | - Tosso Leeb
- Institute of Genetics, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Thomas Bilzer
- Institute of Neuropathology, University Hospital Düsseldorf, Düsseldorf, Germany
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5
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Mickelson JR, Minor KM, Guo LT, Friedenberg SG, Cullen JN, Ciavarella A, Hambrook LE, Brenner KM, Helmond SE, Marks SL, Shelton GD. Sarcoglycan A mutation in miniature dachshund dogs causes limb-girdle muscular dystrophy 2D. Skelet Muscle 2021; 11:2. [PMID: 33407862 PMCID: PMC7789357 DOI: 10.1186/s13395-020-00257-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Accepted: 12/14/2020] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND A cohort of related miniature dachshund dogs with exercise intolerance, stiff gait, dysphagia, myoglobinuria, and markedly elevated serum creatine kinase activities were identified. METHODS Muscle biopsy histopathology, immunofluorescence microscopy, and western blotting were combined to identify the specific pathologic phenotype of the myopathy, and whole genome SNP array genotype data and whole genome sequencing were combined to determine its genetic basis. RESULTS Muscle biopsies were dystrophic. Sarcoglycanopathy, a form of limb-girdle muscular dystrophy, was suspected based on immunostaining and western blotting, where α, β, and γ-sarcoglycan were all absent or reduced. Genetic mapping and whole genome sequencing identified a premature stop codon mutation in the sarcoglycan A subunit gene (SGCA). Affected dachshunds were confirmed on several continents. CONCLUSIONS This first SGCA mutation found in dogs adds to the literature of genetic bases of canine muscular dystrophies and their usefulness as comparative models of human disease.
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Affiliation(s)
- James R Mickelson
- Department of Veterinary and Biomedical Sciences, College of Veterinary Medicine, University of Minnesota, Saint Paul, MN, 55113, USA.
| | - Katie M Minor
- Department of Veterinary and Biomedical Sciences, College of Veterinary Medicine, University of Minnesota, Saint Paul, MN, 55113, USA
| | - Ling T Guo
- Department of Pathology, School of Medicine, University of California San Diego, La Jolla, CA, 92093-0709, USA
| | - Steven G Friedenberg
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, University of Minnesota, Saint Paul, MN, 55113, USA
| | - Jonah N Cullen
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, University of Minnesota, Saint Paul, MN, 55113, USA
| | | | | | - Karen M Brenner
- Centre for Animal Referral and Emergency, Collingwood, Victoria, Australia
| | - Sarah E Helmond
- Animal Referral Hospital, Homebush, New South Wales, Australia
| | - Stanley L Marks
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA, USA
| | - G Diane Shelton
- Department of Pathology, School of Medicine, University of California San Diego, La Jolla, CA, 92093-0709, USA
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6
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Protein Expression of Canine and Feline Muscular Dystrophies. Top Companion Anim Med 2020; 42:100500. [PMID: 33249241 DOI: 10.1016/j.tcam.2020.100500] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 11/07/2020] [Accepted: 11/23/2020] [Indexed: 12/15/2022]
Abstract
Muscular dystrophies in dogs and cats represent a heterogeneous group of inherited, sometimes congenital, but infrequently diagnosed, progressive neuromuscular disorders. A correct identification and characterization of canine and feline muscular dystrophies could increase diagnostic and treatment strategies for veterinary neurologists and could identify useful animal models for the study of human dystrophies. However, in dogs and cats, diagnosis of muscular dystrophies is challenging due to a nonspecific clinical phenotype and pathological lesions, thus is most likely underestimated. We performed immunofluorescence and Western blot techniques using a wide panel of antibodies against proteins involved in human dystrophies (dystrophin mid-rod and carboxyterminal domain, α, β, γ, and δ-sarcoglycan, α-dystroglycan, caveolin-3, emerin, merosin, dysferlin, calpain-3, spectrin epitopes), on 9 canine and 3 feline muscle biopsies characterized by myopathic changes. Dystrophin deficiency was detected in 3 dogs and 2 novel canine muscular dystrophies have been identified, characterized by deficiency of caveolin-3 and calpain-3, respectively. In 2 cats, deficiency of β-SG and carboxyterminal domain of dystrophin in all muscle fibers has been detected. Performing immunofluorescence and Western blot analyses with a wider panel of antibodies allowed a correct identification of muscular dystrophies in dogs and cats and provides a direction for subsequent targeted genetic testing.
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7
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Barthélémy I, Calmels N, Weiss RB, Tiret L, Vulin A, Wein N, Peccate C, Drougard C, Beroud C, Deburgrave N, Thibaud JL, Escriou C, Punzón I, Garcia L, Kaplan JC, Flanigan KM, Leturcq F, Blot S. X-linked muscular dystrophy in a Labrador Retriever strain: phenotypic and molecular characterisation. Skelet Muscle 2020; 10:23. [PMID: 32767978 PMCID: PMC7412789 DOI: 10.1186/s13395-020-00239-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Accepted: 07/09/2020] [Indexed: 12/24/2022] Open
Abstract
Background Canine models of Duchenne muscular dystrophy (DMD) are a valuable tool to evaluate potential therapies because they faithfully reproduce the human disease. Several cases of dystrophinopathies have been described in canines, but the Golden Retriever muscular dystrophy (GRMD) model remains the most used in preclinical studies. Here, we report a new spontaneous dystrophinopathy in a Labrador Retriever strain, named Labrador Retriever muscular dystrophy (LRMD). Methods A colony of LRMD dogs was established from spontaneous cases. Fourteen LRMD dogs were followed-up and compared to the GRMD standard using several functional tests. The disease causing mutation was studied by several molecular techniques and identified using RNA-sequencing. Results The main clinical features of the GRMD disease were found in LRMD dogs; the functional tests provided data roughly overlapping with those measured in GRMD dogs, with similar inter-individual heterogeneity. The LRMD causal mutation was shown to be a 2.2-Mb inversion disrupting the DMD gene within intron 20 and involving the TMEM47 gene. In skeletal muscle, the Dp71 isoform was ectopically expressed, probably as a consequence of the mutation. We found no evidence of polymorphism in either of the two described modifier genes LTBP4 and Jagged1. No differences were found in Pitpna mRNA expression levels that would explain the inter-individual variability. Conclusions This study provides a full comparative description of a new spontaneous canine model of dystrophinopathy, found to be phenotypically equivalent to the GRMD model. We report a novel large DNA mutation within the DMD gene and provide evidence that LRMD is a relevant model to pinpoint additional DMD modifier genes.
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Affiliation(s)
- Inès Barthélémy
- U955 - IMRB, Team 10 - Biology of the neuromuscular system, Inserm, UPEC, EFS, Ecole nationale vétérinaire d'Alfort, 94700, Maisons-Alfort, France
| | - Nadège Calmels
- Laboratoire de biochimie et génétique moléculaire, hôpital Cochin, AP-HP, université Paris Descartes-Sorbonne Paris Cité, Paris, France.,Laboratoire de Diagnostic Génétique-Institut de Génétique Médicale d'Alsace, Hôpitaux Universitaires de Strasbourg, 1 Place de L'Hôpital, 67091, Strasbourg, France
| | - Robert B Weiss
- Department of Human Genetics, The University of Utah School of Medicine, Salt Lake City, Utah, USA
| | - Laurent Tiret
- U955 - IMRB, Team 10 - Biology of the neuromuscular system, Inserm, UPEC, EFS, Ecole nationale vétérinaire d'Alfort, 94700, Maisons-Alfort, France
| | - Adeline Vulin
- SQY Therapeutics, Université de Versailles Saint-Quentin-en-Yvelines, Montigny le Bretonneux, France
| | - Nicolas Wein
- The Center for Gene Therapy, Nationwide Children's Hospital, The Ohio State University, Columbus, Ohio, USA.,Department of Pediatrics, The Ohio State University, Columbus, Ohio, USA
| | - Cécile Peccate
- SQY Therapeutics, Université de Versailles Saint-Quentin-en-Yvelines, Montigny le Bretonneux, France.,Sorbonne Universités, UPMC Université Paris 06, INSERM UMRS974, Centre de Recherche en Myologie, Institut de Myologie, G.H. Pitié Salpêtrière, Paris, France
| | - Carole Drougard
- U955 - IMRB, Team 10 - Biology of the neuromuscular system, Inserm, UPEC, EFS, Ecole nationale vétérinaire d'Alfort, 94700, Maisons-Alfort, France
| | - Christophe Beroud
- Aix Marseille Université, INSERM, MMG, Bioinformatics & Genetics, Marseille, France.,APHM, Hôpital Timone Enfants, Laboratoire de Génétique Moléculaire, Marseille, France
| | - Nathalie Deburgrave
- Laboratoire de biochimie et génétique moléculaire, hôpital Cochin, AP-HP, université Paris Descartes-Sorbonne Paris Cité, Paris, France
| | - Jean-Laurent Thibaud
- U955 - IMRB, Team 10 - Biology of the neuromuscular system, Inserm, UPEC, EFS, Ecole nationale vétérinaire d'Alfort, 94700, Maisons-Alfort, France
| | - Catherine Escriou
- U955 - IMRB, Team 10 - Biology of the neuromuscular system, Inserm, UPEC, EFS, Ecole nationale vétérinaire d'Alfort, 94700, Maisons-Alfort, France
| | - Isabel Punzón
- U955 - IMRB, Team 10 - Biology of the neuromuscular system, Inserm, UPEC, EFS, Ecole nationale vétérinaire d'Alfort, 94700, Maisons-Alfort, France
| | - Luis Garcia
- Université de Versailles Saint-Quentin-en-Yvelines, U1179 INSERM, UFR des Sciences de la Santé, Montigny le Bretonneux, France
| | - Jean-Claude Kaplan
- Laboratoire de biochimie et génétique moléculaire, hôpital Cochin, AP-HP, université Paris Descartes-Sorbonne Paris Cité, Paris, France
| | - Kevin M Flanigan
- The Center for Gene Therapy, Nationwide Children's Hospital, The Ohio State University, Columbus, Ohio, USA.,Department of Pediatrics, The Ohio State University, Columbus, Ohio, USA
| | - France Leturcq
- Laboratoire de biochimie et génétique moléculaire, hôpital Cochin, AP-HP, université Paris Descartes-Sorbonne Paris Cité, Paris, France.,Sorbonne Universités, UPMC Université Paris 06, INSERM UMRS974, Centre de Recherche en Myologie, Institut de Myologie, G.H. Pitié Salpêtrière, Paris, France
| | - Stéphane Blot
- U955 - IMRB, Team 10 - Biology of the neuromuscular system, Inserm, UPEC, EFS, Ecole nationale vétérinaire d'Alfort, 94700, Maisons-Alfort, France.
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8
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Barthélémy I, Hitte C, Tiret L. The Dog Model in the Spotlight: Legacy of a Trustful Cooperation. J Neuromuscul Dis 2020; 6:421-451. [PMID: 31450509 PMCID: PMC6918919 DOI: 10.3233/jnd-190394] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Dogs have long been used as a biomedical model system and in particular as a preclinical proof of concept for innovative therapies before translation to humans. A recent example of the utility of this animal model is the promising myotubularin gene delivery in boys affected by X-linked centronuclear myopathy after successful systemic, long-term efficient gene therapy in Labrador retrievers. Mostly, this is due to unique features that make dogs an optimal system. The continuous emergence of spontaneous inherited disorders enables the identification of reliable complementary molecular models for human neuromuscular disorders (NMDs). Dogs’ characteristics including size, lifespan and unprecedented medical care level allow a comprehensive longitudinal description of diseases. Moreover, the highly similar pathogenic mechanisms with human patients yield to translational robustness. Finally, interindividual phenotypic heterogeneity between dogs helps identifying modifiers and anticipates precision medicine issues. This review article summarizes the present list of molecularly characterized dog models for NMDs and provides an exhaustive list of the clinical and paraclinical assays that have been developed. This toolbox offers scientists a sensitive and reliable system to thoroughly evaluate neuromuscular function, as well as efficiency and safety of innovative therapies targeting these NMDs. This review also contextualizes the model by highlighting its unique genetic value, shaped by the long-term coevolution of humans and domesticated dogs. Because the dog is one of the most protected research animal models, there is considerable opposition to include it in preclinical projects, posing a threat to the use of this model. We thus discuss ethical issues, emphasizing that unlike many other models, the dog also benefits from its contribution to comparative biomedical research with a drastic reduction in the prevalence of morbid alleles in the breeding stock and an improvement in medical care.
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Affiliation(s)
- Inès Barthélémy
- U955 - IMRB, Team 10 - Biology of the neuromuscular system, Inserm, UPEC, EFS, École nationale vétérinaire d'Alfort, Maisons-Alfort, France
| | - Christophe Hitte
- CNRS, University of Rennes 1, UMR 6290, IGDR, Faculty of Medicine, SFR Biosit, Rennes, France
| | - Laurent Tiret
- U955 - IMRB, Team 10 - Biology of the neuromuscular system, Inserm, UPEC, EFS, École nationale vétérinaire d'Alfort, Maisons-Alfort, France
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9
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Clinical and genetic characterisation of dystrophin-deficient muscular dystrophy in a family of Miniature Poodle dogs. PLoS One 2018; 13:e0193372. [PMID: 29474464 PMCID: PMC5825102 DOI: 10.1371/journal.pone.0193372] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Accepted: 02/08/2018] [Indexed: 11/19/2022] Open
Abstract
Four full-sibling intact male Miniature Poodles were evaluated at 4–19 months of age. One was clinically normal and three were affected. All affected dogs were reluctant to exercise and had generalised muscle atrophy, a stiff gait and a markedly elevated serum creatine kinase activity. Two affected dogs also showed poor development, learning difficulties and episodes of abnormal behaviour. In these two dogs, investigations into forebrain structural and metabolic diseases were unremarkable; electromyography demonstrated fibrillation potentials and complex repetitive discharges in the infraspinatus, supraspinatus and epaxial muscles. Histopathological, immunohistochemical and immunoblotting analyses of muscle biopsies were consistent with dystrophin-deficient muscular dystrophy. DNA samples were obtained from all four full-sibling male Poodles, a healthy female littermate and the dam, which was clinically normal. Whole genome sequencing of one affected dog revealed a >5 Mb deletion on the X chromosome, encompassing the entire DMD gene. The exact deletion breakpoints could not be experimentally ascertained, but we confirmed that this region was deleted in all affected males, but not in the unaffected dogs. Quantitative polymerase chain reaction confirmed all three affected males were hemizygous for the mutant X chromosome, while the wildtype chromosome was observed in the unaffected male littermate. The female littermate and the dam were both heterozygous for the mutant chromosome. Forty-four Miniature Poodles from the general population were screened for the mutation and were homozygous for the wildtype chromosome. The finding represents a naturally-occurring mutation causing dystrophin-deficient muscular dystrophy in the dog.
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10
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Abstract
Duchenne muscular dystrophy (DMD) is an X-linked disease caused by mutations in the DMD gene and loss of the protein dystrophin. The absence of dystrophin leads to myofiber membrane fragility and necrosis, with eventual muscle atrophy and contractures. Affected boys typically die in their second or third decade due to either respiratory failure or cardiomyopathy. Despite extensive attempts to develop definitive therapies for DMD, the standard of care remains prednisone, which has only palliative benefits. Animal models, mainly the mdx mouse and golden retriever muscular dystrophy (GRMD) dog, have played a key role in studies of DMD pathogenesis and treatment development. Because the GRMD clinical syndrome is more severe than in mice, better aligning with the progressive course of DMD, canine studies may translate better to humans. The original founder dog for all GRMD colonies worldwide was identified in the early 1980s before the discovery of the DMD gene and dystrophin. Accordingly, analogies to DMD were initially drawn based on similar clinical features, ranging from the X-linked pattern of inheritance to overlapping histopathologic lesions. Confirmation of genetic homology between DMD and GRMD came with identification of the underlying GRMD mutation, a single nucleotide change that leads to exon skipping and an out-of-frame DMD transcript. GRMD colonies have subsequently been established to conduct pathogenetic and preclinical treatment studies. Simultaneous with the onset of GRMD treatment trials, phenotypic biomarkers were developed, allowing definitive characterization of treatment effect. Importantly, GRMD studies have not always substantiated findings from mdx mice and have sometimes identified serious treatment side effects. While the GRMD model may be more clinically relevant than the mdx mouse, usage has been limited by practical considerations related to expense and the number of dogs available. This further complicates ongoing broader concerns about the poor rate of translation of animal model preclinical studies to humans with analogous diseases. Accordingly, in performing GRMD trials, special attention must be paid to experimental design to align with the approach used in DMD clinical trials. This review provides context for the GRMD model, beginning with its original description and extending to its use in preclinical trials.
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Affiliation(s)
- Joe N Kornegay
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, Mail Stop 4458, College Station, TX, 77843-4458, USA.
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11
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Nghiem PP, Bello L, Balog-Alvarez C, López SM, Bettis A, Barnett H, Hernandez B, Schatzberg SJ, Piercy RJ, Kornegay JN. Whole genome sequencing reveals a 7 base-pair deletion in DMD exon 42 in a dog with muscular dystrophy. Mamm Genome 2016; 28:106-113. [PMID: 28028563 PMCID: PMC5371640 DOI: 10.1007/s00335-016-9675-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Accepted: 12/07/2016] [Indexed: 01/03/2023]
Abstract
Dystrophin is a key cytoskeletal protein coded by the Duchenne muscular dystrophy (DMD) gene located on the X-chromosome. Truncating mutations in the DMD gene cause loss of dystrophin and the classical DMD clinical syndrome. Spontaneous DMD gene mutations and associated phenotypes occur in several other species. The mdx mouse model and the golden retriever muscular dystrophy (GRMD) canine model have been used extensively to study DMD disease pathogenesis and show efficacy and side effects of putative treatments. Certain DMD gene mutations in high-risk, the so-called hot spot areas can be particularly helpful in modeling molecular therapies. Identification of specific mutations has been greatly enhanced by new genomic methods. Whole genome, next generation sequencing (WGS) has been recently used to define DMD patient mutations, but has not been used in dystrophic dogs. A dystrophin-deficient Cavalier King Charles Spaniel (CKCS) dog was evaluated at the functional, histopathological, biochemical, and molecular level. The affected dog's phenotype was compared to the previously reported canine dystrophinopathies. WGS was then used to detect a 7 base pair deletion in DMD exon 42 (c.6051-6057delTCTCAAT mRNA), predicting a frameshift in gene transcription and truncation of dystrophin protein translation. The deletion was confirmed with conventional PCR and Sanger sequencing. This mutation is in a secondary DMD gene hotspot area distinct from the one identified earlier at the 5' donor splice site of intron 50 in the CKCS breed.
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Affiliation(s)
- Peter P Nghiem
- Department of Veterinary Integrative Biosciences (Mail Stop 4458), College of Veterinary Medicine, Texas A&M University, College Station, TX, 77843-4458, USA.
| | - Luca Bello
- Department of Neurosciences, University of Padova, Via Giustiniani 5, 35128, Padova, Italy
| | - Cindy Balog-Alvarez
- Department of Veterinary Integrative Biosciences (Mail Stop 4458), College of Veterinary Medicine, Texas A&M University, College Station, TX, 77843-4458, USA
| | - Sara Mata López
- Department of Veterinary Integrative Biosciences (Mail Stop 4458), College of Veterinary Medicine, Texas A&M University, College Station, TX, 77843-4458, USA
| | - Amanda Bettis
- Department of Veterinary Integrative Biosciences (Mail Stop 4458), College of Veterinary Medicine, Texas A&M University, College Station, TX, 77843-4458, USA
| | - Heather Barnett
- Department of Veterinary Integrative Biosciences (Mail Stop 4458), College of Veterinary Medicine, Texas A&M University, College Station, TX, 77843-4458, USA
| | - Briana Hernandez
- Department of Veterinary Integrative Biosciences (Mail Stop 4458), College of Veterinary Medicine, Texas A&M University, College Station, TX, 77843-4458, USA
| | - Scott J Schatzberg
- Veterinary Emergency and Specialty Center of Santa Fe, 2001 Vivigen Way, Santa Fe, NM, 87505, USA
| | - Richard J Piercy
- Department of Clinical Sciences and Services, Royal Veterinary College, London, UK
| | - Joe N Kornegay
- Department of Veterinary Integrative Biosciences (Mail Stop 4458), College of Veterinary Medicine, Texas A&M University, College Station, TX, 77843-4458, USA
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