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Phenotype: Cats affected by hypertrophic cardiomyopathy (HCM) are at risk of sudden cardiac death. Ragdoll cats with two copies of the disease-associated mutation are at high risk of developing severe signs of HCM, usually between 1-2 years of age, and have a greater likelihood of early cardiac death. Cats that carry one copy of the mutation are not likely to show signs of the disease and may live a normal lifespan.
Mode of Inheritance: Autosomal dominant (incomplete penetrance)
Alleles: N = Normal, HCMrd = hypertrophic cardiomyopathy-associated mutation
Breeds appropriate for testing: Ragamuffin, Ragdoll and related outcrosses
Explanation of Results:
- Cats with N/N genotype are not predicted to be at increased risk of HCM and cannot transmit this hypertrophic cardiomyopathy-associated mutation to their offspring.
- Cats with N/HCMrd genotype are not predicted to be at increased risk of HCM, but are carriers. They will transmit this hypertrophic cardiomyopathy-associated mutation to 50% of their offspring.
- Cats with HCMrd/HCMrd genotype are at high risk of developing HCM, a potentially fatal condition.
Hypertrophic cardiomyopathy is the most common cardiac disease in cats. Affected cats are at risk of sudden cardiac death due to defects that produce increased left ventricular heart muscle thickness. In Ragdolls, the condition is inherited due to breed specific mutations in the cardiac myosin binding protein C gene (MYBPC3).
The Ragdoll HCM mutation, known as R820W, is a single base pair change in MYBPC3 that is thought to alter the shape and function of this essential protein for normal heart muscle development. The same R820W mutation has been found to be associated with HCM and left ventricular non-compaction in humans (see reference below, Ripoll et al. 2010). Recent studies show cats that are heterozygous (1 copy) for the mutation are not likely to show signs of the disease and may live a normal lifespan. Homozygous (2 copies) cats for the mutation are at high risk of developing severe HCM signs, usually between 1-2 years of age and have a greater likelihood of early cardiac death. Infrequently, homozygous cats do not show clinical signs of HCM.
Breedings between 2 heterozygous cats are expected to produce 25% high risk kittens. It is not recommended to use cats homozygous for the R820W mutation in a breeding program.
Testing for the Ragdoll HCM mutation to helps owners and breeders identify the Ragdoll HCM status of their cats.
Species
Breed
Type of Test
| Test Result | Ragdoll HCM Status |
|---|---|
| N/N | Normal. Cat does not have the Ragdoll HCM mutation. |
| N/HCMrd | 1 copy of the Ragdoll HCM mutation present. |
| HCMrd/HCMrd | 2 copies of the Ragdoll HCM mutation present. Cat is at high risk for HCM. |
Meurs, K.M., Sanchez, X., David, R.M., Bowles, N.E., Towbin, J.A., Reiser, P.J., Kittleson, J.A., Munro, M.J., Dryburgh, K., MacDonald, K.A., & Kittleson, M.D. (2005). A cardiac myosin binding protein C mutation in the Maine Coon cat with familial hypertrophic cardiomyopathy. Human Molecular Genetics, 14(23), 3587-3593. doi: 10.1093/hmg/ddi386
Meurs, K.M., Norgard, M.M., Ederer, M.M., Hendrix, K.P., & Kittleson, M.D. (2007). A substitution mutation in the myosin binding protein C gene in ragdoll hypertrophic cardiomyopathy. Genomics, 90(2), 261-264. doi: 10.1016/j.ygeno.2007.04.007
Ripoll Vera, T., Monserrat Iglesias, L., Hermida Prieto, M., Ortiz, M., Rodriguez Garcia, I., Govea Callizo, N., Gómez Navarro, C., Rosell Andreo, J., Gámez Martínez, J.M., Pons Lladó, G., Cremer Luengos, D., & Torres Marqués, J. (2010). The R820W mutation in the MYBPC3 gene, associated with hypertrophic cardiomyopathy in cats, causes hypertrophic cardiomyopathy and left ventricular non-compaction in humans. International Journal of Cardiology, 145(2), 405-407. doi: 10.1016/j.ijcard.2010.04.032
