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Maine Coon and Ragdoll hypertrophic cardiomyopathy QPCR

NEW ONLINE HCM SUBMISSION FORM FOR OWNERS AND BREEDERS

 

Maine Coon cat

The Molecular Diagnostic Unit can now offer genetic testing for hypertrophic cardiomyopathy in Maine Coon and Ragdoll cats. Hypertrophic cardiomyopathy (HCM) is the most common form of heart disease found in domestic cats, with affected animals at risk of developing congestive heart failure and occasionally sudden death. HCM can be seen as a secondary complication of some other diseases, usually in older cats and most notably associated with hyperthyroidism. HCM can also be seen in younger cats of specific breeds, including Maine Coons and Ragdolls as a familial disease. Specific genetic mutations have been identified in the cardiac myosin binding protein C gene (MYBPC3) in cats of the Maine Coon and Ragdoll breeds, with the mutations being different in the two breeds. These mutations cause amino acid changes within the cardiac myosin binding protein and are believed to alter the protein structure and function, leading to HCM. It is possible to detect whether a cat has one copy of the defective gene (heterozygous) or two copies (homozygous). There is clear evidence that presence of the mutant gene puts cats at greater risk of developing HCM, and the risk for homozygous cats appears to be greater than that for heterozygous cats, but this correlation is not perfect. This may be because other, as yet unidentified, genetic mutations can also cause HCM or modify the risk. There is some evidence that homozygous mutant cats are more likely to develop moderate to severe disease earlier in life when compared to heterozygous cats. Recent results suggest that the prevalence of the HCM mutation in the UK Maine Coon and Ragdoll populations is currently around 30%.

At the Molecular Diagnostic Unit, Langford Veterinary Services we have developed allele specific QPCR assays to quickly and accurately identify the two MYBPC3 gene mutations currently known to cause HCM in Maine Coon (A31P) and Ragdoll (R820W) cats. The new QPCR assays avoid potential laboratory contamination issues associated with conventional PCR assays, thus providing a very reliable genotyping method.

The assay requires either 0.5ml of EDTA anticoagulated blood or a buccal swab sample.

Interpretation of results

A normal result on either the Maine Coon or Ragdoll HCM genetic test means that the cat does not have the respective genetic mutation. It is possible that some cats may go on to develop cardiac disease due to other, as yet unidentified genetic mutations.

A heterozygous or homozygous result on either the Maine Coon or Ragdoll HCM genetic test means that the cat carries either one (heterozygous) or two (homozygous) mutated copies of the MYBPC3 gene and is likely to develop cardiac disease. Cats that are homozygous for the genetic mutation are highly likely to develop HCM.

Each certificate we issue will specify whether the cat is Normal, Heterozygous or Homozygous for the respective breed specific HCM mutation.

The gene test can also assist breeders in deciding whether or not to use cats for breeding. Generally homozygous affected cats should not be used for breeding because they are certain to pass on the genetic mutation, which will put their offspring at increased risk of developing HCM. There is a 50% probability of a heterozygous cat passing on the genetic mutation when bred with a HCM negative cat. In such cases the offspring should be screened for the genetic mutation and those identified as negative used for future breeding. This strategy can be used as part of a breeding programme to eliminate the defective gene from the Maine Coon and Ragdoll populations.

Further information

 

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