Estimated prevalence of the GYS-1 mutation in healthy Austrian Haflingers.

The research article investigates the prevalence of GYS-1 gene mutation that causes equine polysaccharide storage myopathy (PSSM) type 1 in a population of 50 Austrian Haflingers. They also compare muscle enzyme activity and glucose metabolism parameters in horses with and without the mutation.

Methodology and Findings

• The study used a validated restriction fragment length polymorphism (RFLP) assay for GYS-1 genotyping of 50 Austrian Haflinger horses. This approach was aimed at understanding the occurrence and frequency of this gene mutation.
• The researchers identified 9 horses out of the 50 to be heterozygous for the mutation; essentially, they had one copy of the mutated gene and one normal gene. Strikingly, none of the Haflingers was homozygous, which means carrying two copies of the mutated gene.
• The prevalence of heterozygous GYS-1 mutation in this particular herd was estimated to be as high as 18 per cent.

Muscle Enzyme Activities and Glucose Metabolism

• As part of their study, the researchers also compared resting and post-exercise muscle enzyme activities, as well as parameters of glucose metabolism in blood between horses with and without the mutation.
• The key findings were that the mean resting aspartate aminotransferase (AST) activity and the mean post-exercise creatine kinase and AST activity were significantly higher in horses found to be heterozygous (HR) for the mutation, as compared with homozygote normal (RR) horses. AST and creatine kinase are enzymes released into the bloodstream when muscle damage occurs, so higher levels indicate more muscle damage.
• However, there were no significant differences found in the other parameters of glucose metabolism between the horses with and without the mutation.

Overall Significance

• This study’s findings are crucial because knowing the prevalence of this genetic mutation within the Haflinger population can help stone owners and veterinarians diagnose and manage PSSM, potentially improving the health and performance of these horses.
• The results reveal information about the genetic predisposition of Austrian Haflingers towards this type of myopathy, emphasizing the importance of genetic testing and raising awareness among Haflinger owners about the potential risk of PSSM.