HCM Maine Coon - Feline Hypertrophic Cardiomyopathy
What is HCM Maine Coon – Feline Hypertrophic Cardiomyopathy
HCM (also known as CMH) is a common disease in cats and many mammals.
This disease results in heart failure due to abnormal thickening of the heart muscles.
In the majority of cases, there is a thickening of the left ventricle. The volume of the ventricular chamber and the capacity of contraction and relaxation of the heart are thus altered.
HCM exists in most cat breeds although it is mostly found in Maine Coon, Ragdoll and Sphynx. In Maine Coon, 28% of cats are affected.
Symptoms due to HCM can occur at any age: from a few months old kitten to an adult cat over 10 years old. Cats with heterozygotes often report late, mild HCM, whereas cats with homozygous lesions are usually affected earlier and more severely. Males are often affected earlier and more severely than females.
In some cases, the observed strengthening of the heart wall may be due to other diseases than HCM. The term “secondary HCM” refers to HCM-like symptoms due to other causes such as high blood pressure, kidney disease, certain hormonal diseases such as hyperthyroidism.
On the left a healthy heart, on the right a heart with HCM (thicker walls)
The symptoms of HCM are shortness of breath, increased heart rate, cardiac arrhythmia, heart murmur or breathing problem.
Clinical diagnosis is possible through echocardiography, electrocardiography and radiography. On the other hand, these examinations do not make it possible to diagnose a cat which does not have the symptoms of HCM but which will develop it during its life (cat HCM heterozygote or HCM homozygote).
The limits of these observations also lie in the difficulty of interpretation of the images and the lack of cooperation of echocardiographed cats.
Realization of the genetic test
The DNA test for the detection of HCM can be performed at any age. Like all genetic tests, this test is very reliable.
The test is performed from a buccal swab , quick and easy to perform.Here is the list of the different types of samples that are accepted for this test :
- Buccal swab
- Blood in EDTA tube
- Blood in dry tube
Screening and interpreting the results
On Maine Coon, the assay consists of sequencing the A31P mutation of exon 3 of the MYBPC3 gene (G-to-C substitution).
When this substitution takes place, the structure of the myosin binding protein C is modified. The polymorphism of the A74T mutation has also been suspected to be at the origin of HCM in Maine Coon, but more recent work has shown the absence of a link between HCM and this mutation (Longerich et al. 2013) .
This mutation is hereditary according to a dominant autosomal mode with complete penetrance. This means that this mutation is transmitted to the offspring (hereditary), that it is localized on the non-sexual chromosomes (autosomal), that a single copy of the defective gene causes HCM (dominant) and that the presence of the mutation necessarily leads to HCM (complete penetrance).
A result achieved heterozygous or reached homozygous means that the cat carries the genetic mutation of HCM. This cat will necessarily develop the HCM during his life.
HCM therefore presents a major risk:
- When it comes to a cat for the company, it is important to test the kitten to see if it will develop by the HCM later.
- When the cat is intended for reproduction, it is essential to perform this test to be sure that the latter will not transmit the HCM to their offspring.
The test does not determine the severity and age at which the cat began to have HCM.
Available breed for the test : HCM Maine Coon – Feline Hypertrophic Cardiomyopathy
The following breed is recognized :
- Maine Coon
Understanding results of the test : HCM Maine Coon – Feline Hypertrophic Cardiomyopathy
Gene Mutation : MYBPC c.91G>C
Heredity : autosomal dominant (more information)
Penetrance : complete (more information)
|Test result||HCM Maine Coon – Feline Hypertrophic Cardiomyopathy status (MYBPC c.91G>C)||Health status|
|N/N||No copy of the HCM mutation||Animal is normal (clear)|
|HCM/N||1 copy of the HCM mutation||Animal is, will or could be affected|
|HCM/HCM||2 copies of the HCM mutation||Animal is, will or could be affected|
Cross table of the test : HCM Maine Coon – Feline Hypertrophic Cardiomyopathy
|Mother N/N||Mother HCM/N||Mother HCM/HCM|
|Father N/N||100% N/N||50% N/N|
|Father HCM/N||50% N/N|
|Father HCM/HCM||100% HCM/N||50% HCM/N|
Certificate example for the test : HCM Maine Coon – Feline Hypertrophic Cardiomyopathy
Click on the example certificate below to open it.
K.M. Meurs, et al.: A cardiac myosin binding protein C mutation in the Maine coon cat with familial hypertrophic cardiomyopathy, Hum. Mol. Genet. 14 (2005) 3587-3593.
K. M. Meurs, et al.: A substitution in the myosin binding protein C gene in ragdoll hypertrophic cardiomyopathy, Genomics 90 (2007) 261-264.
Longeri M, Ferrari P, Knafelz P, Mezzelani A, Marabotti A, Milanesi L, Pertica G, Polli M, Brambilla PG, Kittleson M, Lyons LA, Porciello F.: Myosin-binding protein C DNA variants in domestic cats (A31P, A74T, R820W) and their association with hypertrophic cardiomyopathy. J Vet Intern Med. 2013 Mar-Apr;27(2):275-85.