Hypertrophic cardiomyopathy (HCM) is the most common feline heart condition. The Basepaws Breed + Health Cat DNA test now screens for two additional genetic health markers associated with HCM to let pet parents know if their cat is at a higher risk for the disease. This knowledge, along with risk results for any of the 42 other genetic conditions for which the Basepaws test screens, can be incorporated into a proactive care plan that supports the overall health and well-being of a beloved feline companion.
What is hypertrophic cardiomyopathy?
Hypertrophic cardiomyopathy (HCM) is a cardiovascular condition that causes an abnormal thickening of the heart's muscular walls. This thickening makes the heart have to work harder and pump blood faster, leading to an irregularly fast heartbeat known as “tachycardia”. Tachycardia creates a situation where the heart consumes more oxygen than it normally would, often leading to oxygen deprivation and the death of heart cells. HCM compromises overall heart function, which can lead to a range of issues in other systems of the body.
The exact cause of hypertrophic cardiomyopathy (HCM) has yet to be fully understood, but the condition does tend to be more prevalent in certain breeds versus others. Around 30% of Maine Coons have genetic mutations associated with risk of developing HCM, and Ragdolls are also known to be at higher risk for the disease. Other at-risk breeds include the Persian, Birman, Bengal, Turkish Van, and the Abyssinian. Research has also demonstrated the prevalence of HCM in British Shorthairs (see Granström et al., 2011).
Genetic Testing for Earlier Detection and Timely Intervention
Many diseases, including HCM, do not present clinical signs until a pet is already in pain and the disease has reached an advanced stage. This results in the unnecessary suffering of pets and severely limits the options that pet parents and veterinarians might have for managing and treating a disease.
Genetic testing can support earlier detection of and monitoring for diseases like HCM. The Basepaws Cat DNA test screens for genetic markers associated with different diseases and traits. A genetic marker is a specific segment of DNA that has two important characteristics: (1) a known physical location on a chromosome, and (2) a known association with a particular disease (or trait), such as HCM.
For a long time, the only gene with known association to feline HCM was MYBPC3 (Myosin Binding Protein C3). It is a gene that is essential to the proper development of the heart muscle. Two different mutations in this gene (A31P and R820W) were found in Maine Coons (Meurs et al., 2005) and Ragdolls (Meurs et al., 2007), respectively.
Since that time, Basepaws has updated its genetic health marker panel to include two additional genes with mutations associated with hypertrophic cardiomyopathy: the MYH7 (Myosin Heavy Chain 7) gene and the TNNT2 (Troponin T2, Cardiac Type) gene. In 2019, Schipper et al. reported on feline HCM caused by a variant in MYH7, emphasizing that this gene was a candidate to include in future feline genetics research. In 2020, McNamara et al. were the first to demonstrate an association between TNNT2 mutations and HCM in felines, suggesting that TNNT2 should also be included in the list of genetic markers associated with HCM.
The updated Basepaws digital report includes a new five-star scientific evidence grading system to indicate the strength of the scientific evidence that is available in published peer-reviewed literature for each genetic health and trait marker for which the Basepaws test screens. The graphic below shows the number of stars assigned to each mutation in the MYBPC3, TNNT2, or MYH7 gene that the scientific literature associates with a higher risk for feline hypertrophic cardiomyopathy.
The Benefits of Knowing a Cat’s Risk for HCM
The more that we can increase our understanding of the genetics behind diseases like hypertrophic cardiomyopathy, the better the chances are for creating opportunities for earlier detection of disease, intervention and treatment to slow or reverse progression, and, ideally, to prevent a disease from ever becoming a reality.
While there is currently no cure for HCM, knowing a cat’s risk for this disease as early as possible provides more options for proactive care. This knowledge can equip pet parents with a better understanding of the disease and its warning signs, and emphasize the importance of scheduling regular wellness visits with a veterinarian. Genetic mutations for HCM do play a significant role in the potential development of the disease, but they only represent a risk factor—not an official diagnosis, which only a veterinarian can make.
Sharing your cat’s Basepaws digital report with your veterinarian provides an opportunity to get ahead of many health issues before they start. This was the case for Samson (aka Catstradamus), the first cat in the Basepaws feline genetics database to test positive for the A31P mutation in the MYBPC3 gene. As mentioned, this result meant that Samson is at a higher risk for HCM, and that the Basepaws test was able to warn Samson's dad about this risk and inform Samson's veterinarian to create an individualized care plan to meet Samson’s needs.
For example, in the case of cats that may be at a higher risk for HCM, regular monitoring of the heart for any signs of change can be a gamechanger for detecting the development of the disease sooner and, in the event that a cat does develop HCM, an appropriate treatment plan can be implemented under the guidance of a veterinarian to significantly improve disease management and a pet’s overall quality of life.
Implications for HCM in Humans
Did you know that cats have 90.2% of their DNA in common with humans? Cats are genetically closer to humans than are dogs, who only share about 84% of their DNA with us (visit Basepaws’ interesting cat facts blog to learn more). There are also over 200 hereditary human diseases that are closely correlated with feline conditions, and hypertrophic cardiomyopathy is one of them.
HCM also happens to be the most common form of genetic heart disease in humans (affecting at least 1 in 500). The feline HCM phenotype (aka the feline HCM disease presentation) is strikingly similar to the HCM phenotype found in humans though the time frame for the development of the disease in cats is significantly shorter. The two variants in the MYBPC3 gene and the one variant in the MYH7 gene have been implicated in human HCM, and a recent review of the scientific literature by Gil-Ortuño et al. (2020) reveals that the close similarity in the phenotype and genotype between cats and humans makes our furry feline companions an ideal model for the pathophysiological study of HCM and the development and implementation of future therapeutic agents.
Basepaws is advancing the state of pet health genetics to help pets live longer, fuller, and happier lives. We do this with the incredible support of citizen scientists who participate in our different feline genetics research programs so that we can learn more about the feline genome and create products that support the earlier detection of diseases like HCM.
Though hypertrophic cardiomyopathy is an area of interest for Basepaws, some priority feline research programs for which we are currently recruiting U.S.-based citizen scientists include our feline longevity, chronic kidney disease, and feline IBD/GI lymphoma programs. Visit the Basepaws Research page by clicking below to learn more about eligibility and application requirements. Join the Basepaws citizen scientist community where we “let cats do science”!