Brighton and Sussex Medical School, BSMS Building, University of Sussex, Brighton, East Sussex BN1 9PX, UK.
A glycogen synthase 1 mutation associated with equine polysaccharide storage myopathy and exertional rhabdomyolysis occurs in a variety of UK breeds
Article first published online: 5 JAN 2010
2009 EVJ Ltd
Equine Veterinary Journal
Volume 41, Issue 6, pages 597–601, July 2009
How to Cite
Stanley, R. L., Mccue, M. E., Valberg, S. J., Mickelson, J. R., Mayhew, I. G., Mcgowan, C., Hahn, C. N., Patterson-Kane, J. C. and Piercy, R. J. (2009), A glycogen synthase 1 mutation associated with equine polysaccharide storage myopathy and exertional rhabdomyolysis occurs in a variety of UK breeds. Equine Veterinary Journal, 41: 597–601. doi: 10.2746/042516409X407611
- Issue published online: 5 JAN 2010
- Article first published online: 5 JAN 2010
- Paper received for publication 08.10.08; Accepted 01.12.08
- polysaccharide storage myopathy;
- glycogen synthase;
- exertional rhabdomyolysis;
Reasons for performing study: A glycogen synthase (GYS1) mutation has been described in horses with histopathological evidence of polysaccharide storage myopathy (PSSM) in the USA. It is unknown whether the same mutation is present in horses from the UK.
Objectives: To determine whether the GYS1 mutation occurs in UK horses with histopathological evidence of PSSM and exertional rhabdomyolysis.
Hypothesis: The R309H GYS1 mutation is present in a variety of UK horse breeds and that the mutation is commonly associated with exertional rhabdomyolysis.
Methods: DNA was extracted from 47 muscle or blood samples from UK horses with histories of exertional rhabdomyolysis in which muscle biopsy diagnosis had been pursued. The proportions of GYS1 mutation positive cases were compared among histopathologically defined groups. In addition, breeds that carried the GYS1 mutation were identified from a total of 37 grade 2 (amylase-resistant) PSSM cases.
Results: Of 47 horses with exertional rhabdomyolysis in which a muscle biopsy diagnosis was pursued, 10 (21%) carried the GYS1 mutation. The mutation was only found in horses with grade 2 PSSM (i.e. not in horses with normal, idiopathic myopathy or grade 1 PSSM biopsy samples). In total, the GYS1 mutation was found in 24/37 (65%) of grade 2 PSSM cases. A variety of breeds, including Quarter Horse, Appaloosa, Warmblood, Connemara-cross, Cob, Polo Pony and Thoroughbred cross carried the mutation.
Conclusions: The GYS1 mutation is an important cause of exertional rhabdomyolysis of UK horse breeds but does not account for all forms of PSSM.
Potential relevance: Genotyping is recommended in cases of exertional rhabdomyolysis, prior to or in combination with, muscle biopsy. However a significant proportion of horses with histopathological evidence of PSSM and/or exertional rhabdomyolysis have different diseases.