Cardiomyopathy, hypertrophic

Hypertrophic cardiomyopathy (HCM) is the most common heart disease in cats. It causes thickening (hypertrophy) of the heart muscle, especially the left ventricular wall. It limits the volume of the left ventricle and therefore the ability to pump blood efficiently to the body. The disease impairs heart function and can lead to other complications, such as thrombus formation. Clinical symptoms include breathing difficulties, coughing, lethargy and weakness.

In American Shorthair, Exotic Shorthair, Munchkin, Scottish Shorthair and Sphynx, the disease is caused by a missense mutation c.7384G>C in the ALMS1 gene.

The mode of inheritance of the mutation is probably autosomal recessive. This means that only individuals who inherit the mutated gene from both parents will develop the disease. Carriers of the mutated gene are clinically healthy but pass the mutation on to their offspring. In the case of a mating between two heterozygous individuals, theoretically 25% of the offspring will be completely healthy, 50% of the offspring will be carriers and 25% of the offspring will inherit the mutated gene from both parents and will therefore be affected by the disease.

The genetic test can clearly reveal the genotype of the animal and is a useful tool for breeders to prevent unintentional breeding of affected kittens.

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References:

Meurs, K.M., Williams, B.G., DeProspero, D., Friedenberg, S.G., Malarkey, D.E., Ezzell, J.A., Keene, B.W., Adin, D.B., DeFrancesco, T.C., Tou, S. : A deleterious mutation in the ALMS1 gene in a naturally occurring model of hypertrophic cardiomyopathy in the Sphynx cat. Orphanet J Rare Dis 16:108, 2021. Pubmed reference: 33639992