Article

Incidence of Polysaccharide Storage Myopathy: Necropsy Study of 225 Horses

Department of Biomedical Sciences, College of Veterinary Medicine, Magruder 142, Oregon State University, Corvallis, OR 97331, USA.
Veterinary Pathology (Impact Factor: 2.04). 12/2005; 42(6):823-7. DOI: 10.1354/vp.42-6-823
Source: PubMed

ABSTRACT Muscle samples were obtained at necropsy from 225 horses and ponies 1 year of age or older. Samples were processed in routine manner and were stained with hematoxylin and eosin and with periodic acid-Schiff for glycogen. Sections were examined for abnormal glycogen content and amylase-resistant complex polysaccharide and for chronic myopathic change (excessive fiber size variation, increase in number of internal nuclei). A total of 101 horses and ponies with lesions of polysaccharide storage myopathy were identified. Age of affected horses ranged from one to 30 years, with a mean of 14.7 years. Mean age of nonaffected horses was 12 years. Incidence of polysaccharide storage myopathy varied depending on breed; Thoroughbreds had the lowest (27%) and draft-related horses had the highest (86%) incidence. Chronic myopathic changes were more severe in polysaccharide storage myopathy-affected horses than in nonaffected horses. Results of this study indicate that polysaccharide storage myopathy is a common disorder of many breeds of horses and ponies.

0 Followers
 · 
104 Views
  • Source
    • "PSSM1 was first described in detail by Valberg and colleagues in 1992 [9] and is associated with an autosomal dominant, missense, gain of function mutation (R309H) in the skeletal muscle glycogen synthase gene (GYS1) [10]. Suspected to be the result of an ancestral founder, the identical mutation is found in many different horse breeds worldwide, with some breeds, for example Percheron and Belgian Draft horses, having a particularly high disease prevalence [10], [11], [12]. As with some of the known human glycogenoses [13], [14], [15], [16], affected horses accumulate excessive glycogen and abnormal alpha-crystalline polysaccharide inclusions within skeletal muscle fibres, often in sub-sarcolemmal vacuoles or cytoplasmic inclusions [17], [18]. "
    [Show abstract] [Hide abstract]
    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.
    PLoS ONE 07/2012; 7(7):e42317. DOI:10.1371/journal.pone.0042317 · 3.23 Impact Factor
  • Source
    • "More recently, the expression of ubiquitin, a highly conserved protein involved in targeting abnormal cytoplasmic proteins prior to their proteosomal degradation (Alves-Rodrigues et al., 1998), has been detected in the muscle fibres of horses and humans with polysaccharide storage myopathy (Goebel et al., 1992; Valentine et al., 2006). The most commonly associated myopathies described in affected horses include exertional rhabdomyolysis, generalized muscle atrophy and weakness, abnormal pelvic limb gait, pelvic limb muscle atrophy, post-anaesthetic myopathy and spontaneous recumbency with an inability to rise (Valentine and Cooper, 2005). Eleven types of glycogen storage diseases (glycogenoses) have been described in humans. "
    The Veterinary Journal 04/2012; 193(1):152-156. · 2.17 Impact Factor
  • Source
    • "More recently, the expression of ubiquitin, a highly conserved protein involved in targeting abnormal cytoplasmic proteins prior to their proteosomal degradation (Alves-Rodrigues et al., 1998), has been detected in the muscle fibres of horses and humans with polysaccharide storage myopathy (Goebel et al., 1992; Valentine et al., 2006). The most commonly associated myopathies described in affected horses include exertional rhabdomyolysis, generalized muscle atrophy and weakness, abnormal pelvic limb gait, pelvic limb muscle atrophy, post-anaesthetic myopathy and spontaneous recumbency with an inability to rise (Valentine and Cooper, 2005). Eleven types of glycogen storage diseases (glycogenoses) have been described in humans. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Skeletal muscle samples were examined post-mortem in 148 cetaceans over a 12-year period. Histological analysis included haematoxylin and eosin (HE) and periodic acid-Schiff (PAS) staining with and without diastase digestion. In addition, histological muscle sections were immunostained for ubiquitin and fast and slow heavy-chain myosin isoforms. PAS-positive, diastase-resistant inclusions were detected in 26 animals from 11 different species. Older cetaceans were preferentially affected. These intrafibre inclusions varied from large aggregates to multiple coarse granules and were typically associated with type II fibres. All diastase-resistant inclusions were positive for ubiquitin. These features resembled those inclusions described as complex polysaccharide in horses. Based on these histological findings and the ubiquitin staining pattern, a morphological diagnosis of complex polysaccharide storage myopathy is proposed.
    The Veterinary Journal 11/2011; 193(1):152-6. DOI:10.1016/j.tvjl.2011.09.021 · 2.17 Impact Factor
Show more

Preview

Download
4 Downloads
Available from