Maine Orchid



If you read the text under Their heritage it might get clearer why these genetic diseases are present within the breed and/or why it is recommended to test for them in breeding cats.

HCM1 - Meurs mutation - A31P...

One mutation, many names... All names in the headline refer to one mutation, ie a mutation in a gene called MyBPC3 (myosin binding protein 3). The mutation has been connected with an increased risk of developing HCM for Maine coons in several reseach articles.

It was Kathryn Meurs and co-workers who mapped the mutation to this gene in 2006. They discovered that this was a dominant causative mutation for HCM in a group of related Maine coons. The gene codes for a protein that has a stabilising function in the contractive assembly of the heart cell. It is belived that the mutation cause a conformation change in the protein and, hence, make it loose its function. What can be seen in Meurs and others research is that homozygote positive cats (HCM/HCM) have an increased risk in developing HCM. These cats will have no functional MyBPC3 (both versions of the gene is mutated), so it will be hard for the cell to work as it should, and therefore they may develope the disease. A heterozygote positive cat (N/HCM) will have some MyBPC3-proteins that work and some that don't. You could say that the cells work, but they limp. It has been shown that heterozygote cats still have an increased risk of developing the disease compared to normal cats (N/N), but it's not as high as for the homozygote positive cats. Reaserachers belive the mutation is dominant with incomplete penetrance and therefore breeders have been advised to breed away from this mutation.

Not all cats with the mutation develop the disease, and not all cats with the disease carry the mutation. When data was compiled from the PawPeds health programme (for cats with known DNA-status and with ultrasound results) in 2009 it was shown that 47% of the cats with HCM carried this mutation. It's clear that there has to be other reasons for the development of HCM than just this mutation we know of today. This is something researchers have commented on in their work too. In humans we know of over 300 mutations in 13 genes that have been connected to the development of HCM. We currently know about one mutation in one gene in Maine coons today, there will probably be others, we have just not found them yet.

The mutation described here appears to be breed specific for Maine coon. There is another DNA-test for a second mutation in the MyBPC3-gene, often refered to as HCM2 or R820W, that has been connected to HCM in Ragdoll cats. That mutation appear to be breed specific too, and therefor it's no use to test the Maine coons for that mutation. In some labs there's been another test availible for Maine coons, a test often refered to as "Koch's mutation". That test have not been clearly connected to the risk of developing HCM in the same way as HCM1. It is believed that the mutation in that case is a normal variation within the breed (or cats in general), and not causative of HCM.

Information about the health programme and the registered results can be found on the PawPeds website.

Pyruvate kinase deficiency

Pyruvate kinase and the lack of a functional one is still rather new to Maine coon breeders. It was discovered in 2012 by Grahn and co-workers that the mutation known to cause pyruvate kinase deficiency in Abysinian or Somali was also present in the Maine coon population.

Pyruvate kinase is an enzyme present in glycolysis, where glucose is converted to pyruvate and by that provide energy for the cell. Red bloodcells rely on the glycolysis in order to build up the energy needed for its lifetime in circulation. Should this not work, then the cells may die sooner than expected due to lack of energy. If the body can not produce more red bloodcells to compensate for the pre-term death of the cells, then the cat develop anemia. Since the red bloodcells carry oxygen to the organs this may lead to organ failure. Some of the symptoms are fatiue, diarreha, pale mucosa, lack of appetite, bad fur quality, bad immuneresponse, weight loss, icterus, etc. Not all cats show signs of actuall anemia even if they have the disease.

The gene for pyruvate kinase is inherited from both parents. The disease is classified as recessive, which means that you have to inherit the mutation from both parents to develop the disease. A cat with one normal gene and one mutated (N/K) will have a glycolysis that works on "half speed" compared to a normal cat (N/N). A cat that carries the mutation (N/K) will not develop the disease and is classified as healthy. It's interesting to note that this mutation may not be all bad for the cat, since it has not been selected against in the wild feline population. It is suggested, but not confirmed, that the cats that carry the mutation have some sort of protection against some parasites due to this. However, when the cat inherit a mutated gene from both parents (K/K), that's when the cat might get a problem. In that case the red bloodcells will not be able to produce energy in an efficient way. These are the cats that are at risk to develop symptoms of the disease.

Information about this mutation and registration of the cats results can be found on the PawPeds website.



Before you breed your Maine coon it is advised to determine your cats DNA-status for HCM1 and PK-deficiency. According to Swedish regulation it is not allowed to breed animals that carry a trait that could cause suffering for the individual or their offsprings. Cats that are homozygote positve (HCM/HCM or K/K) is therefore not recommended to use in breeding. Cats that are heterozygote positive (N/HCM or N/K) should without exceptions be mated to a negative cat (N/N). Further, when discussing the HCM-mutation it is advised to fase out the carriers from breeding by continuing with a negative offspring. The reason for this is that the mutation is considered dominant, which the mutation for pyruvate kinase deficiency is not.

A known DNA-status for the HCM-mutation does not imply that you should stop examining the cat with ultrasound! Ultrasound is the best method we have to find those cats that develop HCM but do not carry the known mutation!

Last updated: 2014-11-23