Evaluation of cardiac phenotype in horses with type 1 polysaccharide storage myopathy.
Abstract: Type 1 polysaccharide storage myopathy (PSSM1), an equine glycogen storage disorder caused by a gain of function mutation (R309H) in the gene encoding glycogen synthase (GYS1), is associated with the accumulation of amylase-resistant alpha-crystalline polysaccharide inclusions within skeletal muscle. Several glycogenoses in humans have a cardiac phenotype, and reports exist of horses with PSSM and polysaccharide inclusions in cardiac muscle. Objective: To investigate the hypothesis that horses with PSSM1 display a cardiac phenotype. Our objectives were to compare plasma cardiac troponin I (cTnI) concentration and the incidence of cardiac arrhythmias in PSSM1 homozygotes, heterozygotes, and control horses. Methods: One hundred and twenty-five Belgian and Percheron horses under the same management were genotyped for the R309H GYS1 mutation. From these, 8 age-, breed-, and sex-matched cohorts of each genotype were identified. Plasma cTnI concentration and incidence of cardiac arrhythmias (determined by 24-hour Holter ECG) were compared between the groups. Results: Although some PSSM1-affected horses had mildly increased plasma cTnI concentrations, there was no significant difference in cTnI concentrations between groups. There were no significant differences in the incidence of ectopic beats, cardiac conduction intervals or mean heart rate between groups. Conclusions: We found no evidence of clinically relevant cardiac myocyte injury or arrhythmias in horses with PSSM1. Additional study is required to determine whether myocardial function may be compromised in this disorder.
Copyright © 2012 by the American College of Veterinary Internal Medicine.
Publication Date: 2012-09-15 PubMed ID: 22978303DOI: 10.1111/j.1939-1676.2012.00988.xGoogle Scholar: Lookup
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- Journal Article
Summary
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The research article investigates if horses with type 1 polysaccharide storage myopathy (PSSM1), a genetic disorder causing abnormal glycogen storage, show any signs of heart disease. The study found that although some horses with PSSM1 had slightly elevated levels of a marker for heart muscle damage, there were no significant differences in this or in heart rhythm abnormalities between the affected and unaffected horses.
Background and Objectives
- The focus of this study is on type 1 polysaccharide storage myopathy (PSSM1), a condition in horses that results from a mutation in the gene encoding glycogen synthase (GYS1), leading to abnormal glycogen accumulation in the skeletal muscle.
- Given that several human glycogen storage diseases have a heart disease component, the researchers hypothesized that horses with PSSM1 might also exhibit signs of cardiac abnormalities or disease (a ‘cardiac phenotype’).
- To test this hypothesis, the researchers compared the levels of cardiac troponin I (cTnI), a protein that serves as a marker of heart muscle damage when found in the bloodstream, and the incidence of heart rhythm disturbances in horses with different genetic makeups for PSSM1.
Methodology
- A total of 125 Belgian and Percheron horses were genetically tested for the R309H GYS1 mutation indicative of PSSM1.
- Eight groups of horses that were matched by age, breed, and sex were created, each with a distinct genotype (i.e., whether they had one copy, two copies, or none of the mutated gene).
- Plasma cTnI concentrations were measured and 24-hour Holter ECGs, a type of continuous heart monitor, were used to track and compare heart rhythms across the groups.
Results
- The study found that while some PSSM1-affected horses had slightly increased plasma cTnI concentrations, there were no significant differences between groups.
- There were also no significant differences in the incidence of abnormal heart rhythms, the timing of the electrical signals that control heart rhythm (cardiac conduction intervals), or average heart rate between the groups.
Conclusion
- The researchers did not find any evidence of notable heart muscle injury or abnormal heart rhythms in horses with PSSM1 based on this study.
- They concluded that further research is needed to determine if the function of the heart muscle may be impaired in these horses.
Cite This Article
APA
Naylor RJ, Luis-Fuentes V, Livesey L, Mobley CB, Henke N, Brock K, Fernandez-Fuente M, Piercy RJ.
(2012).
Evaluation of cardiac phenotype in horses with type 1 polysaccharide storage myopathy.
J Vet Intern Med, 26(6), 1464-1469.
https://doi.org/10.1111/j.1939-1676.2012.00988.x Publication
Researcher Affiliations
- Comparative Neuromuscular Diseases Laboratory, Veterinary Clinical Sciences, The Royal Veterinary College, London, UK. rnaylor@rvc.ac.uk
MeSH Terms
- Animals
- Arrhythmias, Cardiac / veterinary
- Cohort Studies
- Female
- Genotype
- Heart Diseases / etiology
- Heart Diseases / pathology
- Heart Diseases / veterinary
- Homozygote
- Horse Diseases / genetics
- Horse Diseases / metabolism
- Horse Diseases / pathology
- Horses
- Loss of Heterozygosity
- Male
- Muscular Diseases / complications
- Muscular Diseases / genetics
- Muscular Diseases / veterinary
- Polysaccharides / metabolism
Citations
This article has been cited 3 times.- Shields E, Seiden-Long I, Massie S, Leguillette R. 24-Hour Kinetics of Cardiac Troponin-T Using a "High-Sensitivity" Assay in Thoroughbred Chuckwagon Racing Geldings after Race and Associated Clinical Sampling Guidelines.. J Vet Intern Med 2018 Jan;32(1):433-440.
- 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 2017 Jan;1861(1 Pt A):3388-3398.
- 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(7):e42317.
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