Influence of Clinical Aspects and Genetic Factors on Feline HCM Severity and Development

Abstract

Hypertrophic cardiomyopathy (HCM), which is associated with thickening of the left ventricular wall, is one of the most common heart pathologies in cats. This disease has a hereditary etiology and is primarily related to mutations in the MYBPC3 and MYH7 genes. This study aims to determine the effect of the presence of heterozygosity or homozygosity for the p. A31P mutation (c.91G>C) in the MYBPC3 gene in cats (Maine Coon) of different ages referring to the HCM severity and development, and to compare echocardiographic data and various clinical aspects for the most objective detection of disease in cats of different breeds. The incidence of HCM was 59% of the 103 cases of heart disease in cats in this study. In 23 cats diagnosed with HCM, cats heterozygous for the mutation accounted for 34%, and homozygous cats accounted for 26%. Cats homozygous for this mutation had moderate to severe HCM, suggesting an association with high penetrance of HCM and a significant risk of cardiac death in this group. The penetrance of the heterozygous type was lower than that of the homozygous genotype. This study also indicates that HCM has some age-related penetrance. The disease did not occur in the study group of cats aged up to 1 year, whereas at the age of 7 and older, the percentage of animals diagnosed with HCM was the highest and amounted to 44.3% of the total number of studied cats with HCM.

Keywords: DNA testing; MYBPC3; cats; clinical diagnostics; hypertrophic cardiomyopathy (HCM); p. A31p mutation.

Figure 1

Echocardiographic images (cat, 10 years old, 7.6 kg, Domestic Shorthair), diagnosis: obstructive form of HCM (stage B2), demonstrating anterior systolic mitral motion. (A) transmitral flow, IVRT. (B) left ventricle in M-mode. (C) aorta in relation to the left atrium, dilatation of the left atrium.

Figure 1

Echocardiographic images (cat, 10 years old, 7.6 kg, Domestic Shorthair), diagnosis: obstructive form of HCM (stage B2), demonstrating anterior systolic mitral motion. (A) transmitral flow, IVRT. (B) left ventricle in M-mode. (C) aorta in relation to the left atrium, dilatation of the left atrium.

Figure 2

Dependence of HCM on the A31P mutation.

Figure 3

Dependence of HCM severity on the presence of the p. A31P mutation in the MYBPC3 gene. The drawing was made by the author on the basis of studies conducted in 23 cats diagnosed with HCM; G/C—heterozygous for a mutant allele (one of the copies of the MYBPC3 gene contains the A31P mutation)—8 animals; C/C—homozygous for a mutant allele (two copies of the MYBPC3 gene contain the A31P mutation)—6 animals; G/G—homozygous for the normal allele (both copies of the MYBPC3 gene do not contain the A31P mutation)—9 animals.