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Lindsay-McGee V, Massey C, Li YT, Clark EL, Psifidi A, Piercy RJ. Characterisation of phenotypic patterns in equine exercise-associated myopathies. Equine Vet J 2024. [PMID: 38965932 DOI: 10.1111/evj.14128] [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: 10/09/2023] [Accepted: 06/05/2024] [Indexed: 07/06/2024]
Abstract
BACKGROUND Equine exercise-associated myopathies are prevalent, clinically heterogeneous, generally idiopathic disorders characterised by episodes of myofibre damage that occur in association with exercise. Episodes are intermittent and vary within and between affected horses and across breeds. The aetiopathogenesis is often unclear; there might be multiple causes. Poor phenotypic characterisation hinders genetic and other disease analyses. OBJECTIVES The aim of this study was to characterise phenotypic patterns across exercise-associated myopathies in horses. STUDY DESIGN Historical cross-sectional study, with subsequent masked case-control validation study. METHODS Historical clinical and histological features from muscle samples (n = 109) were used for k-means clustering and validated using principal components analysis and hierarchical clustering. For further validation, a blinded histological study (69 horses) was conducted comparing two phenotypic groups with selected controls and horses with histopathological features characterised by myofibrillar disruption. RESULTS We identified two distinct broad phenotypes: a non-classic exercise-associated myopathy syndrome (EAMS) subtype was associated with practitioner-described signs of apparent muscle pain (p < 0.001), reluctance to move (10.85, p = 0.001), abnormal gait (p < 0.001), ataxia (p = 0.001) and paresis (p = 0.001); while a non-specific classic RER subtype was not uniquely associated with any particular variables. No histological differences were identified between subtypes in the validation study, and no identifying histopathological features for other equine myopathies identified in either subtype. MAIN LIMITATIONS Lack of an independent validation population; small sample size of smaller identified subtypes; lack of positive control myofibrillar myopathy cases; case descriptions derived from multiple independent and unblinded practitioners. CONCLUSIONS This is the first study using computational clustering methods to identify phenotypic patterns in equine exercise-associated myopathies, and suggests that differences in patterns of presenting clinical signs support multiple disease subtypes, with EAMS a novel subtype not previously described. Routine muscle histopathology was not helpful in sub-categorising the phenotypes in our population.
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Affiliation(s)
| | - Claire Massey
- Department of Clinical Sciences and Services, Royal Veterinary College, London, UK
| | - Ying Ting Li
- Department of Clinical Sciences and Services, Royal Veterinary College, London, UK
| | - Emily L Clark
- The Roslin Institute, University of Edinburgh, Edinburgh, UK
| | - Androniki Psifidi
- Department of Clinical Sciences and Services, Royal Veterinary College, London, UK
- The Roslin Institute, University of Edinburgh, Edinburgh, UK
| | - Richard J Piercy
- Department of Clinical Sciences and Services, Royal Veterinary College, London, UK
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Durward-Akhurst SA, Marlowe JL, Schaefer RJ, Springer K, Grantham B, Carey WK, Bellone RR, Mickelson JR, McCue ME. Predicted genetic burden and frequency of phenotype-associated variants in the horse. Sci Rep 2024; 14:8396. [PMID: 38600096 PMCID: PMC11006912 DOI: 10.1038/s41598-024-57872-8] [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: 12/20/2023] [Accepted: 03/22/2024] [Indexed: 04/12/2024] Open
Abstract
Disease-causing variants have been identified for less than 20% of suspected equine genetic diseases. Whole genome sequencing (WGS) allows rapid identification of rare disease causal variants. However, interpreting the clinical variant consequence is confounded by the number of predicted deleterious variants that healthy individuals carry (predicted genetic burden). Estimation of the predicted genetic burden and baseline frequencies of known deleterious or phenotype associated variants within and across the major horse breeds have not been performed. We used WGS of 605 horses across 48 breeds to identify 32,818,945 variants, demonstrate a high predicted genetic burden (median 730 variants/horse, interquartile range: 613-829), show breed differences in predicted genetic burden across 12 target breeds, and estimate the high frequencies of some previously reported disease variants. This large-scale variant catalog for a major and highly athletic domestic animal species will enhance its ability to serve as a model for human phenotypes and improves our ability to discover the bases for important equine phenotypes.
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Affiliation(s)
- S A Durward-Akhurst
- Department of Veterinary Clinical Sciences, University of Minnesota, C339 VMC, 1353 Boyd Avenue, St. Paul, MN, 55108, USA.
| | - J L Marlowe
- Department of Veterinary Clinical Sciences, University of Minnesota, C339 VMC, 1353 Boyd Avenue, St. Paul, MN, 55108, USA
| | - R J Schaefer
- Department of Veterinary Population Medicine, University of Minnesota, 225 VMC, 1365 Gortner Avenue, St. Paul, MN, 55108, USA
| | - K Springer
- Department of Veterinary Population Medicine, University of Minnesota, 225 VMC, 1365 Gortner Avenue, St. Paul, MN, 55108, USA
| | - B Grantham
- Interval Bio LLC, 408 Stierline Road, Mountain View, CA, 94043, USA
| | - W K Carey
- Interval Bio LLC, 408 Stierline Road, Mountain View, CA, 94043, USA
| | - R R Bellone
- Veterinary Genetics Laboratory, School of Veterinary Medicine, University of California-Davis, Davis, CA, USA
- Population Health and Reproduction and Veterinary Genetics Laboratory, School of Veterinary Medicine, University of California, Davis, CA, USA
| | - J R Mickelson
- Department of Veterinary and Biomedical Sciences, University of Minnesota, 295F Animal Science Veterinary Medicine Building, 1988 Fitch Avenue, St. Paul, MN, 55108, USA
| | - M E McCue
- Department of Veterinary Population Medicine, University of Minnesota, 225 VMC, 1365 Gortner Avenue, St. Paul, MN, 55108, USA
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Valberg SJ, Henry ML, Herrick KL, Velez-Irizarry D, Finno CJ, Petersen JL. Absence of myofibrillar myopathy in Quarter Horses with a histopathological diagnosis of type 2 polysaccharide storage myopathy and lack of association with commercial genetic tests. Equine Vet J 2023; 55:230-238. [PMID: 35288976 PMCID: PMC10084132 DOI: 10.1111/evj.13574] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Accepted: 03/10/2022] [Indexed: 12/01/2022]
Abstract
BACKGROUND Genetic tests for variants in MYOT (P2; rs1138656462), FLNC (P3a; rs1139799323 or P3b; rs1142918816) and MYOZ3 (P4; rs1142544043) genes are offered commercially to diagnose myofibrillar myopathy (MFM) and type 2 polysaccharide storage myopathy (PSSM2) in Quarter Horses (QH). OBJECTIVES To determine if PSSM2-QH has histopathological features of MFM. To compare genotype and allele frequencies of variants P2, P3, P4 between control-QH and PSSM2-QH diagnosed by histopathology. STUDY DESIGN Retrospective cross-sectional. METHODS The study includes a total of 229 healthy control-QH, 163 PSSM2-QH GYS1 mutation negative. Desmin stains of gluteal/semimembranosus muscle were evaluated. Purported disease alleles P2, P3a, P3b, P4 were genotyped by pyrosequencing. Genotype, allele frequency and total number of variant alleles or loci were compared between phenotypes using additive/genotypic and dominant models and quantitative effects evaluated by multivariable logistic regression. RESULTS Histopathological features of MFM were absent in all QH. A P variant allele at any locus was not associated (P > .05) with a histopathological diagnosis of PSSM2 and one or more P variants were common in control-QH (57%) and PSSM2-QH (61%). Allele frequencies (control/PSSM2) were: 0.24/0.21 (P2), 0.07/0.12 (P3a), 0.07/0.11 (P3b) and 0.06/0.08 (P4). P3a and P3b loci were not independent (r2 = 0.894); and not associated with PSSM2 histopathology comparing the haplotype of both P3a and P3b variants to other haplotypes. A receiver operator curve did not accurately predict the PSSM2 phenotype (AUC = 0.67, 95% CI 0.62-0.72), and there was no difference in the total number of variant loci or total variant allele count between control-QH and PSSM2-QH. MAIN LIMITATIONS P3a and P3b were not in complete linkage disequilibrium. CONCLUSIONS The P2, P3 and P4 variants in genes associated with human MFM were not associated with PSSM2 in 392 QH. Their use would improperly diagnose PSSM2/MFM in 57% of healthy QH and fail to diagnose PSSM2 in 40% of QH with histopathological evidence of PSSM2.
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Affiliation(s)
- Stephanie J Valberg
- Large Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan, USA
| | - Marisa L Henry
- Large Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan, USA
| | - Keely L Herrick
- Large Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan, USA
| | - Deborah Velez-Irizarry
- Large Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan, USA
| | - Carrie J Finno
- Department of Population Health and Reproduction, School of Veterinary Medicine, University of California-Davis, Davis, California, USA
| | - Jessica L Petersen
- Department of Animal Science, University of Nebraska-Lincoln, Lincoln, Nebraska, USA
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Valberg SJ, Williams ZJ, Finno CJ, Schultz A, Velez‐Irizarry D, Henry ML, Gardner K, Petersen JL. Type 2 polysaccharide storage myopathy in Quarter Horses is a novel glycogen storage disease causing exertional rhabdomyolysis. Equine Vet J 2022. [DOI: 10.1111/evj.13876] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Accepted: 08/11/2022] [Indexed: 11/28/2022]
Affiliation(s)
- Stephanie J. Valberg
- Michigan State University, Large Animal Clinical Sciences College of Veterinary Medicine East Lansing MI USA
| | - Zoë J. Williams
- Michigan State University, Large Animal Clinical Sciences College of Veterinary Medicine East Lansing MI USA
| | - Carrie J. Finno
- University of California‐Davis, Department of Population Health and Reproduction, School of Veterinary Medicine Davis CA USA
| | - Abigail Schultz
- Michigan State University, Large Animal Clinical Sciences College of Veterinary Medicine East Lansing MI USA
| | - Deborah Velez‐Irizarry
- Michigan State University, Large Animal Clinical Sciences College of Veterinary Medicine East Lansing MI USA
| | - Marisa L. Henry
- Michigan State University, Large Animal Clinical Sciences College of Veterinary Medicine East Lansing MI USA
| | - Keri Gardner
- Michigan State University, Large Animal Clinical Sciences College of Veterinary Medicine East Lansing MI USA
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Integrated proteomic and transcriptomic profiling identifies aberrant gene and protein expression in the sarcomere, mitochondrial complex I, and the extracellular matrix in Warmblood horses with myofibrillar myopathy. BMC Genomics 2021; 22:438. [PMID: 34112090 PMCID: PMC8194174 DOI: 10.1186/s12864-021-07758-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Accepted: 05/26/2021] [Indexed: 02/06/2023] Open
Abstract
Background Myofibrillar myopathy in humans causes protein aggregation, degeneration, and weakness of skeletal muscle. In horses, myofibrillar myopathy is a late-onset disease of unknown origin characterized by poor performance, atrophy, myofibrillar disarray, and desmin aggregation in skeletal muscle. This study evaluated molecular and ultrastructural signatures of myofibrillar myopathy in Warmblood horses through gluteal muscle tandem-mass-tag quantitative proteomics (5 affected, 4 control), mRNA-sequencing (8 affected, 8 control), amalgamated gene ontology analyses, and immunofluorescent and electron microscopy. Results We identified 93/1533 proteins and 47/27,690 genes that were significantly differentially expressed. The top significantly differentially expressed protein CSRP3 and three other differentially expressed proteins, including, PDLIM3, SYNPO2, and SYNPOL2, are integrally involved in Z-disc signaling, gene transcription and subsequently sarcomere integrity. Through immunofluorescent staining, both desmin aggregates and CSRP3 were localized to type 2A fibers. The highest differentially expressed gene CHAC1, whose protein product degrades glutathione, is associated with oxidative stress and apoptosis. Amalgamated transcriptomic and proteomic gene ontology analyses identified 3 enriched cellular locations; the sarcomere (Z-disc & I-band), mitochondrial complex I and the extracellular matrix which corresponded to ultrastructural Z-disc disruption and mitochondrial cristae alterations found with electron microscopy. Conclusions A combined proteomic and transcriptomic analysis highlighted three enriched cellular locations that correspond with MFM ultrastructural pathology in Warmblood horses. Aberrant Z-disc mechano-signaling, impaired Z-disc stability, decreased mitochondrial complex I expression, and a pro-oxidative cellular environment are hypothesized to contribute to the development of myofibrillar myopathy in Warmblood horses. These molecular signatures may provide further insight into diagnostic biomarkers, treatments, and the underlying pathophysiology of MFM. Supplementary Information The online version contains supplementary material available at 10.1186/s12864-021-07758-0.
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Urschel KL, McKenzie EC. Nutritional Influences on Skeletal Muscle and Muscular Disease. Vet Clin North Am Equine Pract 2021; 37:139-175. [PMID: 33820605 DOI: 10.1016/j.cveq.2020.12.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Skeletal muscle comprises 40% to 55% of mature body weight in horses, and its mass is determined largely by rates of muscle protein synthesis. In order to support exercise, appropriate energy sources are essential: glucose can support both anaerobic and aerobic exercise, whereas fat can only be metabolized aerobically. Following exercise, ingestion of nonfiber carbohydrates and protein can aid muscle growth and recovery. Muscle glycogen replenishment is slow in horses, regardless of dietary interventions. Several heritable muscle disorders, including type 1 and 2 polysaccharide storage myopathy and recurrent exertional rhabdomyolysis, can be managed in part by restricting dietary nonstructural carbohydrate intake.
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Affiliation(s)
- Kristine L Urschel
- Department of Animal and Food Sciences, University of Kentucky, 612 W.P. Garrigus Building, Lexington, KY 40546, USA
| | - Erica C McKenzie
- Department of Clinical Sciences, Carlson College of Veterinary Medicine, Oregon State University, 227 Magruder Hall, 700 Southwest 30th Street, Corvallis, OR 97331, USA.
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Wright S. Highlights of recent clinically relevant papers. EQUINE VET EDUC 2020. [DOI: 10.1111/eve.13422] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Valberg SJ, Finno CJ, Henry ML, Schott M, Velez-Irizarry D, Peng S, McKenzie EC, Petersen JL. Commercial genetic testing for type 2 polysaccharide storage myopathy and myofibrillar myopathy does not correspond to a histopathological diagnosis. Equine Vet J 2020; 53:690-700. [PMID: 32896939 PMCID: PMC7937766 DOI: 10.1111/evj.13345] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 07/18/2020] [Accepted: 08/27/2020] [Indexed: 02/04/2023]
Abstract
Background Commercial genetic tests for type 2 polysaccharide storage myopathy (PSSM2) and myofibrillar myopathy (MFM) have not been validated by peer‐review, and formal regulation of veterinary genetic testing is lacking. Objectives To compare genotype and allele frequencies of commercial test variants (P variants) in MYOT (P2; rs1138656462), FLNC (P3a; rs1139799323), FLNC (P3b; rs1142918816) and MYOZ3 (P4; rs1142544043) between Warmblood (WB) and Arabian (AR) horses diagnosed with PSSM2/MFM by muscle histopathology, and phenotyped breed‐matched controls. To quantify variant frequency in public repositories of ancient and modern horse breeds. Study design Cross sectional using archived clinical material and publicly available data. Methods We studied 54 control‐WB, 68 PSSM2/MFM‐WB, 30 control‐AR, 30 PSSM2/MFM‐AR and 205 public genotypes. Variants were genotyped by pyrosequencing archived DNA. Genotype and allele frequency, and number of variant alleles or loci were compared within breed between controls, PSSM2/MFM combined and MFM or PSSM2 horses considered separately using additive/genotypic and dominant models (Fisher's exact tests). Variant frequencies in modern, early domestic and Przewalski horses were determined from a public data repository. Results There was no significant association between any P locus and a histopathological diagnosis of PSSM2/MFM, and no difference between control and myopathic horses in total loci with alternative alleles, or total alternate alleles when PSSM2/MFM was considered combined or separately as PSSM2 or MFM. For all tests, sensitivity was <0.33. Allele frequencies in WB (controls/cases) were: 8%/15% (P2), 5%/6% (P3a/b) and 9%/13% (P4); in AR, frequencies were: 12%/17% (P2), 2%/2% (P3a/b) and 7%/12% (P4). All P variants were present in early domestic (400‐ to 5500‐year‐old) horses and P2 present in the Przewalski. Conclusions Because of the lack of significant association between a histopathological diagnosis of PSSM2 or MFM and the commercial genetic test variants P2, P3 and P4 in WB and AR, we cannot recommend the use of these variant genotypes for selection and breeding, prepurchase examination or diagnosis of a myopathy.
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Affiliation(s)
- Stephanie J Valberg
- Large Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, MI, USA
| | - Carrie J Finno
- Department of Population Health and Reproduction, School of Veterinary Medicine, University of California-Davis, Davis, CA, USA
| | - Marisa L Henry
- Large Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, MI, USA
| | - Melissa Schott
- Large Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, MI, USA
| | - Deborah Velez-Irizarry
- Large Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, MI, USA
| | - Sichong Peng
- Department of Population Health and Reproduction, School of Veterinary Medicine, University of California-Davis, Davis, CA, USA
| | - Erica C McKenzie
- Department of Clinical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis, OR, USA
| | - Jessica L Petersen
- Department of Animal Science, University of Nebraska-Lincoln, Lincoln, NE, USA
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