Genetic mutations have been identified in both the Maine Coon and Ragdoll breeds of cat, and there is ongoing work looking for further mutations in the Norwegian Forest Cat and Spynx.  Within the Maine Coon breed, approximately one third of tested cats are positive for the mutation.  However, not all Maine Coons with HCM are positive and this particular mutation has not been identified in any cats other that Maine Coons and their progeny.  The mutation identified in the Ragdoll is located within the same gene as the Maine Coon mutation.  However, this mutation is different to that identified in Maine Coons.

Genetic testing of affected cats can be useful in identifying which cats carry the mutation.  Whilst a positive test result means that the cat is genetically predisposed to HCM, unfortunately a negative test only means that the cat does not have that one particular mutation.  It does not mean that the cat being tested doesn’t have HCM. For more information on the gene test see below.

Some new information about HCM DNA testing from Dr Leslie Lyons:

http://www.vetmed.ucdavis.edu/Catgenetics/HCM_statement_UCD_Lyons.pdf

HCM Gene Test for Maine Coon and Ragdoll

Hypertrophic cardiomyopathy (HCM) is the most common form of heart disease found in domestic cats, which affected animals at risk of developing congestive heart failure and sudden death.  Feline HCM appears to be more common in some breeds, including Maine Coons and Ragdolls.

In some HCM affected cats a single genetic defect has been identified in heart muscle.  Maine Coon and Ragdoll breeds have different defects in the same gene (MYBPC3).  Since the cat genome contains two copies of this gene there are three possible genotypes:

Homozygous wild-type (two copies of the normal gene, i.e.no defective gene).  This means the cat is negative for this particular form of HCM.Heterozygous (one copy of the normal gene and one copy of the defective gene).  This means the cat may develop this form of HCM.Homozygous mutant (two copies of the defective gene).  There is some evidence that these cats are more likely to develop moderate to severe disease earlier in life when compared to heterozygous cats.

Please note

A negative result on either the Maine Coon or Ragdoll HCM genetic test means that the cat does not have this specific genetic mutation.  However, cats may still go on to develop HCM due to other mutations, as yet unidentified, but for which there is already considerable evidence of existence.  In addition, cats may also develop other forms of heart disease for other reasons, for example, associated with high blood pressure.

A positive result on either the Maine Coon or Ragdoll HCM genetic test means that the cat carries either one (heterozygous) or two (homozygous) defective copies of the MYBPC3 gene and is likely to develop cardiac disease.  All results will specify whether a genotype is heterozygous or homozygous.