The short answer: The Maine Coon is one of America’s most beloved cats, ranked #2 among CFA registrations in 2024. Hypertrophic cardiomyopathy (HCM) is the most common feline heart disease, and the Maine Coon is tied to a specific variant, MYBPC3 A31P, which research reports was the first feline HCM mutation ever identified (Meurs et al., 2005). Here is the crucial part: this variant is a risk factor with incomplete penetrance, meaning a cat carrying it may never develop clinical HCM. The DNA test is information — useful for awareness and breeding decisions — not a diagnosis. Actual heart-muscle thickening is diagnosed by a veterinarian using echocardiography (a heart ultrasound). Because DNA doesn’t change, the gene test is a one-time step; the smartest approach is to pair it with periodic veterinary heart screening rather than treat it as a verdict.
What MYBPC3 and HCM actually are
Hypertrophic cardiomyopathy is a disease of the heart muscle in which the walls of the left ventricle become abnormally thick. That thickening can stiffen the heart and interfere with how efficiently it fills and pumps blood. HCM is recognized as the most common heart disease in cats, and it can appear across many breeds and in mixed-breed cats too.
MYBPC3 is the gene that codes for cardiac myosin binding protein C, a scaffold-like protein that helps organize and regulate the machinery heart-muscle cells use to contract. Research associates certain changes in this protein with the abnormal thickening seen in HCM, which is why variants in MYBPC3 have drawn so much attention in feline cardiology.
The Maine Coon and the A31P variant
SamA coworker keeps saying every Maine Coon has this mutation — is that true? Elena MarshNo — UC Davis reports that roughly 63–70% of tested Maine Coons are actually variant-free, so carriers are common but far from universal.The Maine Coon connection is where feline HCM genetics began. Meurs and colleagues (2005) described a mutation in the MYBPC3 gene — known as A31P — in Maine Coons with familial hypertrophic cardiomyopathy. This was the first feline HCM mutation ever identified, and it opened the door to DNA screening for the breed.
Being a carrier is not universal, though. According to the UC Davis Veterinary Genetics Laboratory, roughly 63–70% of tested Maine Coons are free of the A31P variant. In other words, carriers are common enough to matter for breeders and owners, but a large share of the tested population does not carry it at all.
Why HCM matters
SamA coworker’s cat seems totally fine, so why would a vet still want to check its heart? Elena MarshBecause HCM is frequently silent early on; the Kittleson and Côté (2021) review notes it can progress to heart failure or thromboembolism, so screening catches what symptoms hide.HCM deserves attention because it is often silent. Many cats show no obvious symptoms in the early stages, and the disease can progress quietly. When it does advance, research describes serious complications: congestive heart failure, arterial thromboembolism (often a “saddle thrombus” that lodges where the aorta divides toward the hind legs), and in some cats sudden death.
Because the disease can be hidden, veterinary heart screening is the practical safeguard. A veterinarian can listen for murmurs or gallop rhythms and, when indicated, recommend imaging to look directly at the heart muscle — regardless of what any gene test says.
Carrier vs affected
SamA coworker asked if a positive test basically means her cat is already sick. Elena MarshIt doesn’t — carrying the variant is a predisposition, and because A31P shows incomplete penetrance (Meurs 2005), a positive result is not a diagnosis of disease.It helps to separate two very different ideas: being a genetic carrier and being clinically affected. Carrying the A31P variant means a cat has a DNA change associated with increased risk. Being affected means a veterinarian has actually documented abnormal heart-muscle thickening. These are not the same thing, and one does not guarantee the other.
Zygosity — whether a cat has one copy (heterozygous) or two copies (homozygous) of the variant — is part of the risk picture, and research reports the variant shows incomplete penetrance. That is precisely why a positive result is not a sentence: many carriers live full lives without ever developing clinical HCM.
What the DNA test can and cannot tell you
SamA coworker wants to know if the gene test can just tell her whether her cat has HCM. Elena MarshIt can’t — the test reports variant status, not heart health; echocardiography by a veterinarian is the clinical test that actually assesses the heart muscle.The DNA test can tell you whether a cat carries the A31P variant and how many copies it has. That is genuinely useful information for awareness and for breeding decisions, since it helps reduce the spread of a known risk variant. What it cannot do is diagnose HCM, predict with certainty whether a given cat will develop it, or measure the actual state of the heart muscle.
For the clinical question — is this heart thickened right now? — echocardiography performed by a veterinarian is the tool that answers it. It’s also worth noting the DNA test only covers this one known variant; a “clear” gene result does not rule out HCM arising from other causes. The sensible plan is to treat the gene test as one-time background information and pair it with ongoing veterinary heart screening.
FAQ — Frequently Asked Questions
Q. Do I need the test if my Maine Coon seems healthy?
The DNA test is optional information rather than a medical necessity. Because HCM is often silent and the A31P variant carries incomplete penetrance, a healthy-looking cat can still be a carrier — and a carrier may still stay healthy. Many owners find the test most useful for breeding decisions, and pair it with periodic veterinary heart screening for peace of mind.
Q. Does a positive mean my cat will get HCM?
No. Research reports the A31P variant is a risk factor with incomplete penetrance, so carrying it is associated with increased risk but does not guarantee disease. Many carriers never develop clinical HCM. A positive result is a reason to discuss heart screening with your veterinarian, not a diagnosis.
Q. If the test is negative/clear, is my cat safe from HCM?
Not entirely. The DNA test only covers this one known Maine Coon variant, so a clear result does not rule out HCM arising from other causes. That is why echocardiography by a veterinarian remains the clinical way to assess the heart, regardless of gene test results.
Q. Is the result valid for life?
Yes for the gene itself — DNA doesn’t change, so variant status is a one-time result. However, heart health can change over time, so the recommended approach is to pair the one-time DNA information with ongoing veterinary heart screening.
References
- Meurs KM, et al. (2005) A cardiac myosin binding protein C mutation in the Maine Coon cat with familial hypertrophic cardiomyopathy. Hum Mol Genet 14(23):3587-3593. https://pubmed.ncbi.nlm.nih.gov/16236761/
- Kittleson MD, Côté E. (2021) The Feline Cardiomyopathies. J Feline Med Surg. https://pubmed.ncbi.nlm.nih.gov/34693838/
- UC Davis Veterinary Genetics Laboratory — Maine Coon HCM (MYBPC3). https://vgl.ucdavis.edu/
- Cat Fanciers’ Association — Most Popular Breeds. https://cfa.org/
How to get your pet tested
Some pet DNA tests screen for hereditary-disease carrier status or genetic risk markers, but the results are information, not a diagnosis. If your pet has symptoms or you need a confirmed diagnosis, please consult your veterinarian.
Below is where HCM (MYBPC3) can be tested, grouped by where you live and marked by whether each service explicitly lists this variant.
In the United States
In the United Kingdom
In India
We could not verify a service in this region that explicitly lists this variant. Please ask your veterinarian.
Elsewhere
Worried about your pet’s health? — Talk to a veterinarian
A confirmed diagnosis and any treatment plan are decisions for a veterinarian, not a test kit. The links below are professional resources.
AVMA — Find a veterinarian (American Veterinary Medical Association)
This section contains advertising (affiliate links); we may earn a commission if you buy through them. Genetic tests do not guarantee the prevention, diagnosis, or treatment of any disease — results indicate tendencies and provide information only.
This page is educational information, not veterinary diagnosis or advice. Always consult a veterinarian about your pet’s health.
About the author
Elena Marsh
Editor & writer (not a veterinarian)
A writer with a molecular-biology background and a lifelong dog and cat owner. Not a veterinarian — she translates peer-reviewed genetics research and primary data into plain language, always as information rather than diagnosis.
