Hypertrophic cardiomyopathy (HCM) is the most common heart disease in cats. This causes the muscles of the left ventricle to thicken, making it harder for the heart to fill. This can lead to poor performance, shortness of breath, blood clots and, in the worst case, sudden cardiac death.

In addition to ultrasound examinations, specific genetic tests are available for some breeds: The HCM1 variant in the MYBPC3 gene has been described in the Maine Coon, the HCM3 variant in the MYBPC3 gene in the Ragdoll and the HCM4 variant in the ALMS1 gene in the Sphynx. These variants are considered high-risk factors that can provide an indication of the development of the disease even before the clinical signs appear. Nevertheless, severe, symptomatic forms of the disease usually only develop in combination with other genetic or environmental factors – a reliable prognosis of the clinical course is therefore not possible on the basis of genetic analyses alone. In addition, these are very breed-specific variants for which a correlation with the occurrence of the disease could only be proven in the breeds described in each case.

The evaluation of the samples submitted to us between 2012 and 2022 showed a significant decrease in the HCM3 allele frequency within the Ragdoll breed from 28.6 % to 4.3 %, which is probably due to breeding efforts. The current distribution of genotypes in the Ragdoll can be seen in the diagram opposite. In addition, we tested around 28,000 cats of various breeds – in particular British Shorthair, Maine Coon and Persian – for the Ragdoll variant HCM3. Outside of the Ragdoll breed, it only occurred in negligible numbers, although it is unclear whether there is a correlation with clinical symptoms. We therefore continue to recommend the HCM3 test exclusively for the Ragdoll breed.