Myofibrillar myopathy (MFM) is a neuromuscular condition affecting horses, characterized by structural abnormalities in muscle fibers. This disorder involves the disintegration of myofibrils, the contractile elements of muscle cells, leading to muscle weakness and exercise intolerance. MFM is identified by the presence of specific protein aggregates within the muscle tissue, which can be detected through muscle biopsy. The condition is observed in various horse breeds, with some showing a genetic predisposition. Research on myofibrillar myopathy focuses on understanding its pathophysiology, genetic factors, and potential management strategies. This page compiles peer-reviewed research studies and scholarly articles that explore the diagnosis, underlying mechanisms, and implications of myofibrillar myopathy in equine health.
Valberg SJ, Henry ML, Herrick KL, Velez-Irizarry D, Finno CJ, Petersen JL.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). Objective: 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. Methods: Retrospective cross-sectional. Methods: The study includes a total of 229 healthy control-QH, 163 PSSM2-QH GYS1 ...
Williams ZJ, Velez-Irizarry D, Gardner K, Valberg SJ.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 m...
Valberg SJ, Finno CJ, Henry ML, Schott M, Velez-Irizarry D, Peng S, McKenzie EC, Petersen JL.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. Objective: 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 reposi...
Williams ZJ, Velez-Irizarry D, Petersen JL, Ochala J, Finno CJ, Valberg SJ.Myofibrillar myopathy (MFM) of unknown aetiology has recently been identified in Warmblood (WB) horses. In humans, 16 genes have been implicated in various MFM-like disorders. Objective: To identify variants in 16 MFM candidate genes and compare allele frequencies of all variants between MFM WB and non-MFM WB and coding variants with moderate or severe predicted effects in MFM WB with publicly available data of other breeds. To compare differential gene expression and muscle fibre contractile force between MFM and non-MFM WB. Methods: Case-control. Methods: 8 MFM WB, 8 non-MFM WB, 33 other WB,...
Valberg SJ, Nicholson AM, Lewis SS, Reardon RA, Finno CJ.To report a novel exertional myopathy, myofibrillar myopathy (MFM) in Warmblood (WB) horses. Objective: To 1) describe the distinctive clinical and myopathic features of MFM in Warmblood horses and 2) investigate the potential inheritance of MFM in a Warmblood family. Methods: Retrospective selection of MFM cases and prospective evaluation of a Warmblood family. Methods: Retrospectively, muscle biopsies were selected from Warmblood horses diagnosed with MFM and clinical histories obtained (n = 10). Prospectively, muscle biopsies were obtained from controls (n = 8) and a three generation WB...
Valberg SJ, McKenzie EC, Eyrich LV, Shivers J, Barnes NE, Finno CJ.Although exertional rhabdomyolysis (ER) is common in Arabian horses, there are no dedicated studies describing histopathological characteristics of muscle from Arabian horses with ER. Objective: To prospectively identify distinctive histopathological features of muscle from Arabian endurance horses with a history of ER (pro-ER) and to retrospectively determine their prevalence in archived samples from Arabian horses with exertional myopathies (retro-ER). Methods: Prospective and retrospective histopathological description. Methods: Middle gluteal muscle biopsies obtained from Arabian controls ...
Williams ZJ, Velez-Irizarry D, Gardner K, Valberg SJ.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 m...
Williams ZJ, Velez-Irizarry D, Petersen JL, Ochala J, Finno CJ, Valberg SJ.Myofibrillar myopathy (MFM) of unknown aetiology has recently been identified in Warmblood (WB) horses. In humans, 16 genes have been implicated in various MFM-like disorders. Objective: To identify variants in 16 MFM candidate genes and compare allele frequencies of all variants between MFM WB and non-MFM WB and coding variants with moderate or severe predicted effects in MFM WB with publicly available data of other breeds. To compare differential gene expression and muscle fibre contractile force between MFM and non-MFM WB. Methods: Case-control. Methods: 8 MFM WB, 8 non-MFM WB, 33 other WB,...
Valberg SJ, Finno CJ, Henry ML, Schott M, Velez-Irizarry D, Peng S, McKenzie EC, Petersen JL.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. Objective: 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 reposi...
Valberg SJ, Henry ML, Herrick KL, Velez-Irizarry D, Finno CJ, Petersen JL.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). Objective: 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. Methods: Retrospective cross-sectional. Methods: The study includes a total of 229 healthy control-QH, 163 PSSM2-QH GYS1 ...
Valberg SJ, McKenzie EC, Eyrich LV, Shivers J, Barnes NE, Finno CJ.Although exertional rhabdomyolysis (ER) is common in Arabian horses, there are no dedicated studies describing histopathological characteristics of muscle from Arabian horses with ER. Objective: To prospectively identify distinctive histopathological features of muscle from Arabian endurance horses with a history of ER (pro-ER) and to retrospectively determine their prevalence in archived samples from Arabian horses with exertional myopathies (retro-ER). Methods: Prospective and retrospective histopathological description. Methods: Middle gluteal muscle biopsies obtained from Arabian controls ...
Valberg SJ, Nicholson AM, Lewis SS, Reardon RA, Finno CJ.To report a novel exertional myopathy, myofibrillar myopathy (MFM) in Warmblood (WB) horses. Objective: To 1) describe the distinctive clinical and myopathic features of MFM in Warmblood horses and 2) investigate the potential inheritance of MFM in a Warmblood family. Methods: Retrospective selection of MFM cases and prospective evaluation of a Warmblood family. Methods: Retrospectively, muscle biopsies were selected from Warmblood horses diagnosed with MFM and clinical histories obtained (n = 10). Prospectively, muscle biopsies were obtained from controls (n = 8) and a three generation WB...
