DNA test for HCM - information and recommendations (updated April 2007)

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A gene test is available, since last year (2006), for identifying cats with a specific genetic mutation in the Myosin Binding Protein C 3 (MyBPC 3) gene, also called HCM1. This mutation has been shown to be associated with HCM in a colony of Maine Coon cats. It is now clear that this mutation is also associated with an increased risk for clinical HCM in the general Maine Coon cat population. It is currently not known exactly how increased this risk is. Future prospective studies are required to obtain more precise risk estimates.

It should be noted that in humans with the same disease, there are many different genetic mutations which can cause this disease. Presumably, the situation is similar in cats. In the statistics currently available, approximately half of the Maine Coon cats, which have been diagnosed with HCM by echocardiography or necropsy have the HCM1 mutation. Obviously, the remaining half have HCM from other causes, probably other mutations.

This means that the absence of the mutation in a cat DOES NOT mean that it will never develop HCM. It means that it does not have the only presently known mutation that can cause the disease in the cat. In the future, additional mutations may be identified that may be tested for as well. Cats that are positive for the test will not necessarily develop significant heart disease and die from the disease. Some cats will develop a very mild form of the disease and will live quite comfortably, and some might even never develop any signs of the disease. It is not known at this time what makes one cat with the mutation develop HCM early, while another cat develops a much milder and later form, or no signs at all of any heart disease. Hopefully, more will be known about this in the future.

We propose the following recommendations regarding genetic testing for HCM1:

  • It is recommended that all Maine Coon cats which are to be used for breeding are tested to determine their status, unless the cat's parents are both known to be negative for the mutation.
  • It is not recommended to use this gene test for cats of any other breed, unless they have Maine Coon cats behind them in their pedigree, as this particular mutation has so far only been found in Maine Coons and cats related to Maine Coons.
  • It is recommended to continue to screen the cats with ultrasound because that will help to detect cats with HCM caused by a mutation other than HCM1.
  • Breeding decisions should be made carefully. At this time the labs have reported about 33-35% positive among the Maine Coon cats that they have tested. This means that about one third of all Maine Coon cats seem to have at least one copy of the gene. Removal of all of these cats from the breeding population could be very dangerous for the future health of the breed. For this reason, it is NOT recommended that all cats heterozygous for the mutation (have ONE copy of the mutated gene) should be immediately removed from the breeding program. Heterozygotes can be used, if the cat is considered important for maintaining genetic variation. Since there is presently no objective way to say exactly which cats are important to maintain genetic variation and which are not, it will have to be up to the individual cat owner to use his/her own judgement here. A heterozygous cat should only be bred to an unaffected negative cat, to decrease the risk of producing affected cats. With progress, negative kittens from these lines should be selected for breeding.
  • It is not recommended to use homozygous cats (have TWO copies of the mutated gene).

Keep in mind that the scientific progress in this area is high and that recommendations may be altered, as more information becomes available.

Testing your cat

If you wish to DNA test your cat(s) for the MyBPC 3 mutation, this is possible in several laboratories. Here are some of the laboratories who perform this test (please note that this is not an exhaustive list, there might be other labs who do this also):

  • U.S.A: Washington State University (Dr Kate Meurs) - website
  • Germany: Laboklin - website
  • France : Antagène - website

The test is performed out of EDTA whole blood (0.5-1 ml) or special cytobrushes. If you wish to ship blood samples, please note that there might be special requirements to send blood to certain countries, your post office will be able to inform you. The cytobrushes are available upon request from the respective labs. Your veterinary should verify the cat's ID (microchip or tattoo) before taking blood or swabbing the cat. Most labs provide information on the procedure to use the cytobrushes. In order to register your results in the health programme, they should be sent to the DNA Registrar of the health programme.

For the time being, we will accept to publish results of cats that were not ID checked; the result in PawPeds will then carry the remark: No permanent ID. However, we urge owners to have the identity verified by their vet as the trust in the registry might be affected negatively if too many results lack this verification. If we receive too many results lacking the ID check in the future, we might have to start refusing to publish these results in order to maintain the credibility of the health programme.