HCM – Hypertrophic Cardiomyopathy
HCM is a heart disease that can be found in all cats, also housecats, and it is in fact the most common heart problem in cats. In Maine Coons, a related colony of cats affected with HCM was studied to discover more about this illness, and there has been more research in our breed than other breeds. This does not mean that there is more HCM in Maine Coons than other cats, but we know a lot more about it.
- Approximately 10 % of Maine Coon (2018 numbers) carry a mutation that increases risk of getting HCM
- Approximately 5-15 % of Maine Coons will develop HCM during their life
- Offspring of tested lines have much lower risk than offspring of non-tested lines
HCM health programme – DNA testing and echocardigraphy
Most Maine Coon breeders test for the main factor that can cause HCM, the A31P mutation in the MyBPC3 gene. This genetic test is only one indication of risk of getting ill with HCM later in life, but it seems to be responsible for many of the cases. Cats who have “double” of the affected gene (homozygous positive) have a very high risk of getting ill, and a slightly higher risk is also seen in those with one gene (heterozygous positive), but these cats will typically stay healthy until at least 4-5 years old and those who get ill might not be as seriously affected (Longeri 2013).
- N/N: normal risk (around 5 %)
- N/A31P HCM: almost 2 times risk
- A31P HCM/A31P HCM: around 18 times risk
However there are cats who suffer from HCM who are N/N (negative) for the MyBPC3 A31P gene, implying that there must be other yet undiscovered factors involved.
Ultrasound – echocardiography
To check for HCM it is necessary to scan for clinical HCM through ultrasound (echocardiography), and this test needs to be repeated several times in a cat’s life. The most important is to first scan young breeding cats before they are mated the first time, in order to leave the most serious cases who get HCM early out of breeding. Then also very important is to scan middle aged or older breeding cats (over 8 years), as the disease usually develops quite late in life.
We scan (ultrasound) our breeding animals according to the PawPeds health programme. Their recommendations are ultrasound scans at 1, 2, 3, 5 and 8 years of age, always by a veterinary cardiologist with special training, see list.
Patterns of matings:
It is very important to know A31P status to avoid homozygous positives who have a very high risk of illness.
Overview of all the research done on A31P and HCM in Maine Coons
Read my article on HCM/A31P in MCO and research:
Berge. 2014. “A31P DNA-test and HCM in Maine Coon.”
Berge. 2014. “A31P DNA-test og HCM-sykdom hos Maine Coon”
List of reference papers with links to full text under Research papers below.
Excerpt with findings
Comparing the numbers from all the research studies (table 2), a more complete picture can be seen. The number of cats in a study, the gene frequency of A31P for those cats, and the number of affected cats can all influence the results of a single study.
Wess who concluded that A31P had no effect on HCM, also had the smallest study, and the gene frequency for A31P in his study was significantly lower in his study than in all the other studies. The number of cats diagnosed with HCM was also higher than the supposed prevalence for HCM in the breed. This could have influenced the conclusion. Longeri who also did a meta study based on Longeri, Mary and Wess arrived at similar numbers that we see in table 2 regarding disease prevalence and gene frequency.
Summed up these studies show:
- Homozygous cats have a highly increased risk to get HCM, with few cats without signs of illness at 4-5 years of age.
- Heterozygous cats also have an increased risk, but the disease strikes much later and often after 5-8 years of age. Over half of the cats are healthy at 5 years of age.
- A high number of the HCM-affected Maine Coons do have this mutation.
Summary and Conclusion
Summing up the results of all the studies, it is clear that there is a strong correlation between the A31P mutation and development of HCM. It is also clear that HCM is found among cats without this mutation, so there are other causes in addition to A31P.
Both DNA-testing with a gradual selection away from the mutaton from the gene pool, and repeated ultrasound scans (echocardiography) by a cardiologist are necessary to limit the cases of HCM in the Maine Coon breed.
Research papers on HCM
HCM and the A31P mutation in Maine Coon
- Carlos Sampedrano, Carolina. et al. 2009. “Prospective echocardiographic and tissue Doppler imaging screening of a population of Maine Coon cats tested for the A31P mutation in the myosin-binding protein C gene: a specific analysis of the heterozygous status.” In: Journal of Veterinary Internal Medicine. 2009; 23:91–99
- Fries R, et al. 2008. “Prevalence of the Myosin-binding Protein C Mutation in Maine Coon Cats.” In: Journal of Veterinary Internal Medicine. 22:893-896, 2008.
- Godiksen, Mia. et al. 2013. “Feline Hypertrophic Cardiomyopathy Associated with the p.A31P Mutation in cMyBP-C Is Caused by Production of Mutated cMyBP-C with Reduced Binding to Actin.” In: Open Journal of Veterinary Medicine, 2013, 3, 95-103 doi:10.4236/ojvm.2013.32016 Published Online June 2013
- Godiksen, Mia, et al. 2011. “Hypertrophic cardiomyopathy in young Maine Coon cats caused by the p.A31P cMyBP-C mutation–the clinical significance of having the mutation.” In: Acta Veterinaria Scandinavica 2011, 53:7
- Gundler, Suzanne, et al. 2008. “Prevalence of myocardial hypertrophy in a population of asymptomatic Swedish Maine coon cats.” In: Acta Veterinaria Scandinavica. 2008, 50:22 doi:10.1186/1751-0147-50-22
- Longeri, Maria. et al. 2013. “Myosin-Binding Protein C DNA Variants in Domestic Cats (A31P, A74T, R820W) and their Association with Hypertrophic Cardiomyopathy.” In: Journal of Veterinary Internal Medicine 10.1111/jvim.12031
- Mary Jérôme, et al. 2010. “Prevalence of the MYBPC3-A31P mutation in a large European feline population and association with hypertrophic cardiomyopathy in the Maine Coon breed.” In: Journal of Veterinary Cardiology (2010) 12, 155e161.
- Meurs, Kathryn, et al. 2005. “A cardiac myosin binding protein C mutation in the Maine Coon cat with familial hypertrophic cardiomyopathy.” In: Human Molecular Genetics (2005) Vol.14, No. 23, doi:10.1093/hmg/ddi386.
- Wess, Gerhard, et al. 2010. “Association of A31P and A74T polymorphisms in the myosin binding protein C3 gene and hypertrophic cardiomyopathy in Maine Coon and other breed cats.” In: Journal of Veterinary Internal Medicine. 2010; 24:527–532.
Other HCM research
- Freeman, Lisa M. et al. 2013. “Body size and metabolic differences in Maine Coon cats with and without hypertrophic cardiomyopathy.” In: Journal of Feline Medicine and Surgery 2013 15: 74
- Meurs, Kathryn, et al. 2007. “A substitution mutation in the myosin binding protein C gene in Ragdoll hypertrophic cardiomyopathy.” In: Genomics 2007; 90:261–264.
- Trehiou-Sechi, Emilie, et al. 2012. “Comparative echocardiographic and clinical features of hypertrophic cardiomyopathy in 5 breeds of cats: a retrospective analysis of 344 cases (2001-2011).” In: Journal of Veterinary Internal Medicine. 2012 May-Jun; 26(3):532-41. doi: 10.1111/j.1939-1676.2012.00906.x.
- PawPeds Health Programme for HCM, started by Maine Coon-katten breed society in January 2004.
- IG Herzgesunde Katzen, interest group for heart disease in cats, founded 2012 in Mannheim.
- IG Herzgesunde Katzen’s summary of PawPeds statistics on HCM
I happen to feel that the degree of a person’s intelligence is directly reflected by the number of conflicting attitudes she can bring to bear on the same topic.
– Lisa Alther