Genotyping of additional 35 IMM and 22 unaffected QHs confirmed an association (P 2.9 105) and the putative mutation was absent in 175 horses from 21 non-QH breeds. Protein modeling identified 14 residues affected by the mutation, which signifi- cantly decreased stability.
4. Conclusions
The authors conclude that a mutation in MYH1 is highly associated with susceptibility to the IMM phe- notype in QH-related breeds. This is the first report of a mutation in MYH1 and the first link between a skeletal muscle myosin mutation and autoimmune disease.1
Acknowledgments
Declaration of Ethics The Authors have adhered to the Principles of Veter- inary Medical Ethics of the AVMA.
Conflict of Interest
Dr. Valberg is one of the owners of the patent for the PSSM genetic test and receives sales income from its use. Her financial interest has been reviewed and managed by the University in accordance with its conflict of interest policies. Michigan State University and the University of California, Davis have applied for a patent for the E321G MYH1 genetic mutation test.
References
1. Finno CJ, Giuliana G, Perumbakkam S, et al. A mutation in MYH1 is associated with susceptibility to immune- mediated myositis in Quarter Horses. Skelet Muscle 2018; 8(1):7.
2. Valberg SJ, Henry ML, Perumbakkam S, et al. An E321G MYH1 mutation is strongly associated with nonexertional rhabdomyolysis in Quarter Horses. J Vet Int Med 2018. doi: 10.1111/jvim.15299.
