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Abstract
There are 5 single-gene mutations that are known to cause muscle disease in horses. These mutations alter the amino acid sequence of proteins involved in cell membrane electrical conduction, muscle energy metabolism, muscle contraction, and immunogenicity. The clinical signs depend on the pathway affected. The likelihood that an animal with a mutation will exhibit clinical signs depends on the mode of inheritance, environmental influences, and interactions with other genes. Selection of a genetic test for use in diagnostic or breeding decisions requires a knowledge of clinical signs, mode of inheritance, breeds affected, and proper scientific test validation.
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Karlíková R, Široká J, Mech M, Friedecký D, Janečková H, Mádrová L, Hrdinová F, Drábková Z, Dobešová O, Adam T, Jahn P. Newborn foal with atypical myopathy. J Vet Intern Med 2018; 32:1768-1772. [PMID: 30216546 PMCID: PMC6189353 DOI: 10.1111/jvim.15236] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Revised: 04/18/2018] [Accepted: 05/09/2018] [Indexed: 12/20/2022] Open
Abstract
The case of atypical myopathy (AM) in newborn Haflinger foal with clinical signs of depression and weakness appearing 6 hours after birth resulting in recumbency 12 hours after birth is described. The foal's dam was diagnosed with AM in the 6th month of gestation based on clinical signs of a myopathy, elevated serum activity of creatine kinase, metabolomic analysis and the presence of methylenecyclopropyl acetyl carnitine (MCPA‐carnitine) in the blood. At the time of delivery, the mare was grazing on a pasture near sycamore trees but was free of clinical signs of AM. Metabolomic analysis of the foal's blood revealed increased concentrations of acylcarnitines and MCPA‐carnitine consistent with metabolic profiles of blood from AM affected horses. Two theories could explain this observation (a) hypoglycin A or its metabolites accumulated in the mare's placenta with consequent transfer to fetus or (b) these compounds were secreted into mare's milk.
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Affiliation(s)
- Radana Karlíková
- Department of Clinical Biochemistry, University Hospital Olomouc, Olomouc, Czech Republic.,Faculty of Medicine and Dentistry, Palacký University, Institute of Molecular and Translational Medicine, Olomouc, Czech Republic
| | - Jitka Široká
- Faculty of Medicine and Dentistry, Palacký University, Institute of Molecular and Translational Medicine, Olomouc, Czech Republic.,Faculty of Science, Laboratory of Growth Regulators, Centre of the Region Haná for Biotechnological and Agricultural Research, Palacký University and Institute of Experimental Botany ASCR, Olomouc, Czech Republic
| | - Marek Mech
- Private Veterinary Practice, Jistebník, Czech Republic
| | - David Friedecký
- Department of Clinical Biochemistry, University Hospital Olomouc, Olomouc, Czech Republic.,Faculty of Medicine and Dentistry, Palacký University, Institute of Molecular and Translational Medicine, Olomouc, Czech Republic.,Laboratory for Inherited Metabolic Disorders, University Hospital, and Palacký University, Olomouc, Czech Republic
| | - Hana Janečková
- Faculty of Medicine and Dentistry, Palacký University, Institute of Molecular and Translational Medicine, Olomouc, Czech Republic.,Laboratory for Inherited Metabolic Disorders, University Hospital, and Palacký University, Olomouc, Czech Republic
| | - Lucie Mádrová
- Department of Clinical Biochemistry, University Hospital Olomouc, Olomouc, Czech Republic.,Faculty of Medicine and Dentistry, Palacký University, Institute of Molecular and Translational Medicine, Olomouc, Czech Republic
| | - Františka Hrdinová
- Faculty of Veterinary Medicine, Equine Clinic, University of Veterinary and Pharmaceutical Sciences, Brno, Czech Republic
| | - Zuzana Drábková
- Faculty of Veterinary Medicine, Equine Clinic, University of Veterinary and Pharmaceutical Sciences, Brno, Czech Republic
| | - Olga Dobešová
- Faculty of Veterinary Medicine, Equine Clinic, University of Veterinary and Pharmaceutical Sciences, Brno, Czech Republic
| | - Tomáš Adam
- Department of Clinical Biochemistry, University Hospital Olomouc, Olomouc, Czech Republic.,Faculty of Medicine and Dentistry, Palacký University, Institute of Molecular and Translational Medicine, Olomouc, Czech Republic.,Laboratory for Inherited Metabolic Disorders, University Hospital, and Palacký University, Olomouc, Czech Republic
| | - Petr Jahn
- Faculty of Veterinary Medicine, Equine Clinic, University of Veterinary and Pharmaceutical Sciences, Brno, Czech Republic
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Maile CA, Hingst JR, Mahalingan KK, O'Reilly AO, Cleasby ME, Mickelson JR, McCue ME, Anderson SM, Hurley TD, Wojtaszewski JFP, Piercy RJ. A highly prevalent equine glycogen storage disease is explained by constitutive activation of a mutant glycogen synthase. Biochim Biophys Acta Gen Subj 2016; 1861:3388-3398. [PMID: 27592162 DOI: 10.1016/j.bbagen.2016.08.021] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Revised: 08/15/2016] [Accepted: 08/30/2016] [Indexed: 01/16/2023]
Abstract
BACKGROUND Equine type 1 polysaccharide storage myopathy (PSSM1) is associated with a missense mutation (R309H) in the glycogen synthase (GYS1) gene, enhanced glycogen synthase (GS) activity and excessive glycogen and amylopectate inclusions in muscle. METHODS Equine muscle biochemical and recombinant enzyme kinetic assays in vitro and homology modelling in silico, were used to investigate the hypothesis that higher GS activity in affected horse muscle is caused by higher GS expression, dysregulation, or constitutive activation via a conformational change. RESULTS PSSM1-affected horse muscle had significantly higher glycogen content than control horse muscle despite no difference in GS expression. GS activity was significantly higher in muscle from homozygous mutants than from heterozygote and control horses, in the absence and presence of the allosteric regulator, glucose 6 phosphate (G6P). Muscle from homozygous mutant horses also had significantly increased GS phosphorylation at sites 2+2a and significantly higher AMPKα1 (an upstream kinase) expression than controls, likely reflecting a physiological attempt to reduce GS enzyme activity. Recombinant mutant GS was highly active with a considerably lower Km for UDP-glucose, in the presence and absence of G6P, when compared to wild type GS, and despite its phosphorylation. CONCLUSIONS Elevated activity of the mutant enzyme is associated with ineffective regulation via phosphorylation rendering it constitutively active. Modelling suggested that the mutation disrupts a salt bridge that normally stabilises the basal state, shifting the equilibrium to the enzyme's active state. GENERAL SIGNIFICANCE This study explains the gain of function pathogenesis in this highly prevalent polyglucosan myopathy.
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Affiliation(s)
- C A Maile
- Comparative Neuromuscular Diseases Laboratory, Department of Clinical Sciences and Services, Royal Veterinary College, London, UK
| | - J R Hingst
- Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Denmark
| | - K K Mahalingan
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, USA
| | - A O O'Reilly
- School of Natural Sciences and Psychology, Liverpool John Moores University, Liverpool, UK
| | - M E Cleasby
- Department of Comparative Biomedical Sciences, Royal Veterinary College, London, UK
| | - J R Mickelson
- Veterinary Biomedical Sciences Department, University of Minnesota, St. Paul, MN, USA
| | - M E McCue
- Veterinary Population Medicine Department, University of Minnesota, St. Paul, MN, USA
| | - S M Anderson
- Veterinary Population Medicine Department, University of Minnesota, St. Paul, MN, USA
| | - T D Hurley
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, USA
| | - J F P Wojtaszewski
- Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Denmark
| | - R J Piercy
- Comparative Neuromuscular Diseases Laboratory, Department of Clinical Sciences and Services, Royal Veterinary College, London, UK.
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Druml T, Grilz-Seger G, Neuditschko M, Brem G. Association between population structure and allele frequencies of the glycogen synthase 1 mutation in the Austrian Noriker draft horse. Anim Genet 2016; 48:108-112. [PMID: 27476720 DOI: 10.1111/age.12481] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/30/2016] [Indexed: 11/29/2022]
Abstract
The aim of this study was to determine the allele frequency of the glycogen synthase 1 (GYS1) mutation associated with polysaccharide storage myopathy type 1 in the Austrian Noriker horse. Furthermore, we examined the influence of population substructures on the allele distribution. The study was based upon a comprehensive population sample (208 breeding stallions and 309 mares) and a complete cohort of unselected offspring from the year 2014 (1553 foals). The mean proportion of GYS1 carrier animals in the foal cohort was 33%, ranging from 15% to 50% according to population substructures based on coat colours. In 517 mature breeding horses the mutation carrier frequency reached 34%, ranging on a wider scale from 4% to 62% within genetic substructures. We could show that the occurrence of the mutated GYS1 allele is influenced by coat colour; genetic bottlenecks; and assortative, rotating and random mating strategies. Highest GYS1 carrier frequencies were observed in the chestnut sample comprising 50% in foals, 54% in mares and 62% in breeding stallions. The mean inbreeding of homozygous carrier animals reached 4.10%, whereas non-carrier horses were characterized by an inbreeding coefficient of 3.48%. Lowest GYS1 carrier frequencies were observed in the leopard spotted Noriker subpopulation. Here the mean carrier frequency reached 15% in foals, 17% in mares and 4% in stallions and inbreeding decreased from 3.28% in homozygous non-carrier horses to 2.70% in heterozygous horses and 0.94% in homozygous carriers. This study illustrates that lineage breeding and specified mating strategies result in genetic substructures, which affect the frequencies of the GYS1 gene mutation.
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Affiliation(s)
- T Druml
- Institute of Animal Breeding and Genetics, University of Veterinary Sciences Vienna, Veterinärplatz 1, Vienna, A-1210, Austria
| | | | - M Neuditschko
- Agroscope, Swiss National Stud Farm, Les Longs Prés, CH-1580, Avenches, Switzerland
| | - G Brem
- Institute of Animal Breeding and Genetics, University of Veterinary Sciences Vienna, Veterinärplatz 1, Vienna, A-1210, Austria
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Schröder U, Licka TF, Zsoldos R, Hahn CN, MacIntyre N, Schwendenwein I, Schwarz B, Van Den Hoven R. Effect of Diet on Haflinger Horses With GYS1 Mutation (Polysaccharide Storage Myopathy Type 1). J Equine Vet Sci 2015. [DOI: 10.1016/j.jevs.2015.03.197] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Affiliation(s)
- R. J. Naylor
- Comparative Neuromuscular Diseases Laboratory; Veterinary Clinical Sciences; The Royal Veterinary College; London UK
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Naylor RJ, Livesey L, Schumacher J, Henke N, Massey C, Brock KV, Fernandez-Fuente M, Piercy RJ. Allele copy number and underlying pathology are associated with subclinical severity in equine type 1 polysaccharide storage myopathy (PSSM1). PLoS One 2012; 7:e42317. [PMID: 22860112 PMCID: PMC3409190 DOI: 10.1371/journal.pone.0042317] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Accepted: 07/02/2012] [Indexed: 11/28/2022] Open
Abstract
Equine type 1 polysaccharide storage myopathy (PSSM1), a common glycogenosis associated with an R309H founder mutation in the glycogen synthase 1 gene (GYS1), shares pathological features with several human myopathies. In common with related human disorders, the pathogenesis remains unclear in particular, the marked phenotypic variability between affected animals. Given that affected animals accumulate glycogen and alpha-crystalline polysaccharide within their muscles, it is possible that physical disruption associated with the presence of this material could exacerbate the phenotype. The aim of this study was to compare the histopathological changes in horses with PSSM1, and specifically, to investigate the hypothesis that the severity of underlying pathology, (e.g. vacuolation and inclusion formation) would (1) be higher in homozygotes than heterozygotes and (2) correlate with clinical severity. Resting and post-exercise plasma creatine kinase (CK) and aspartate aminotransferase (AST) enzyme activity measurements and muscle pathology were assessed in matched cohorts of PSSM1 homozygotes, heterozygotes or control horses. Median (interquartile range (IR)) resting CK activities were 364 (332–764) U/L for homozygotes, 301 (222–377) U/L for heterozygotes and 260 (216–320) U/L for controls, and mean (+/− SD) AST activity for homozygotes were 502 (+/116) U/L, for heterozygotes, 357 (+/−92) U/L and for controls, 311 (+/−64) U/L and were significantly different between groups (P = 0.04 and P = 0.01 respectively). Resting plasma AST activity was significantly associated with the severity of subsarcolemmal vacuolation (rho = 0.816; P = 0.01) and cytoplasmic inclusions (rho = 0.766; P = 0.01). There were fewer type 2× and more type 2a muscle fibres in PSSM1-affected horses. Our results indicate that PSSM1 has incomplete dominance. Furthermore, the association between plasma muscle enzyme activity and severity of underlying pathology suggests that physical disruption of myofibres may contribute to the myopathic phenotype. This work provides insight into PSSM1 pathogenesis and has implications for related human glycogenoses.
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Affiliation(s)
- Rosie J. Naylor
- Comparative Neuromuscular Diseases Laboratory, The Royal Veterinary College, London, United Kingdom
| | - Leanda Livesey
- Auburn University, Auburn, Alabama, United States of America
| | - John Schumacher
- Auburn University, Auburn, Alabama, United States of America
| | - Nicole Henke
- Auburn University, Auburn, Alabama, United States of America
| | - Claire Massey
- Comparative Neuromuscular Diseases Laboratory, The Royal Veterinary College, London, United Kingdom
| | - Kenny V. Brock
- Auburn University, Auburn, Alabama, United States of America
| | - Marta Fernandez-Fuente
- Comparative Neuromuscular Diseases Laboratory, The Royal Veterinary College, London, United Kingdom
| | - Richard J. Piercy
- Comparative Neuromuscular Diseases Laboratory, The Royal Veterinary College, London, United Kingdom
- * E-mail:
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