Dr. Kathryn Meurs of North Carolina State University has recently made an incredible discovery in the Sphynx breed. After over a decade of research, she has identified one genetic mutation in roughly 60% of HCM cases in the breed. This highlights the importance of her continued research to locate the other mutation(s) responsible for the other 40% of cases. If you would like to make a direct donation to Dr. Meurs HCM research, you can do so by donating to the “Gus Fund” using this link; https://securelb.imodules.com/s/1209/give19/form.aspx?sid=1209&gid=214&pgid=7348&cid=11690&bledit=1&sort=1&dids=5940&appealcode=LB000256
So, what does this mean for Breeders? Simply put, this is an additional tool to be used in conjunction with yearly echocardiograph screening. North Carolina State University now has a simple DNA test, with the affordable price tag of $40. You can order DNA collection kits to be mailed to you, so that you can either collect the buccal sample yourself, or have your Veterinarian do so for you. Once the samples are mailed back, you will receive an email confirming receipt of the sample, and results within the next few weeks. A negative result means that your cat does not have this mutation that can cause HCM, but they still might have an unidentified mutation that can cause HCM so echocardiograms are still a necessary proactive mitigation tool regardless of the DNA results. A heterozygous positive result (one copy of the mutation, and one copy of a normal gene) means this cat is at an increased risk for developing HCM, and can pass on that potentially deleterious gene to 50% of it’s progeny (statistically). A homozygous positive result (two copies of the mutation) means this cat is at an increased risk for developing HCM and will pass on the mutation to 100% of it’s progeny. It is not yet confirmed if homozygous positive Sphynx are at an increased risk compared to heterozygous positive Sphynx. The penetrance percentage, which is the percentage of cats with this mutation that will develop HCM, is roughly 70% for heterozygous and homozygous positive cats as a whole. We do not yet know the specific penetrance percentage between heterozygous positives, and homozygous positives individually. In Maine Coons, heterozygous positives have a roughly 20% risk of developing HCM, where as homozygous positives have a roughly 70% risk of developing HCM. Dr. Meurs will work to determine these numbers for us in Sphynx though so that we can have a more accurate ability to assess risk.
So, what are the breeding recommendations? Dr. Meurs cautions against the removal of all cats with this mutation, as this can have a drastically negative impact on gene pool diversity, and advises individual risk and benefit assessment on a cat by cat basis. She recommends valuable heterozygous positive cats be bred to negative cats, with the purpose of slowly weaning out positives without irreparably diminishing the breed’s genetic diversity. Homozygous positive cats should be unequivocally removed from breeding programs.
What does this mean for pet owners? In addition to regular DNA panels and echocardiograms, you will be able to request the results of this Sphynx HCM risk gene for any prospective new family member, or you can simply order the test yourself so that you and your Veterinarian can be more proactive about your cat or kitten’s health. It’s important to keep in mind, a positive result (heterozygous or homozygous) does not mean your cat or kitten will ever develop HCM. HCM is a very complex disease, and while genetic mutations are causative for disease, they are also heavily influenced by other factors, like other genes (protective modifier genes), diet, lifestyle, viruses, etc. This DNA test is not a diagnosis for HCM, it’s more accurate to think of it as a risk identifier. A Sphynx with two copies of the mutation can live into their late teens with a beautiful healthy heart for example, where as a Sphynx negative for this mutation might die of heart failure at 1 year old. This new test is just one more piece of the puzzle, and in combination with echocardiograms and careful breeding choices, will help us reduce the prevalence of HCM in our breed.
If you want to order a DNA collection kit use this link; https://cvm.ncsu.edu/nc-state-vet-hospital/small-animal/genetics/submit-dna-testing/nc-state-veterinary-hospital-small-animal-veterinary-genetics-cardiac-health/nc-state-veterinary-hospital-small-animal-veterinary-genetics-sphynx-cat-hypertrrophic-cardiomyopathy/
If you are ordering many, it might be worthwhile to email them directly to see if a discount is offered, at this email address; vcgl@lists.ncsu.edu
Dr. Meurs is still in need of saliva DNA samples of HCM positive Sphynx. If you have an HCM positive Sphynx and would like to donate a DNA sample to help in her continued research, you can email Dr. Meurs at kate_meurs@ncsu.edu
She might also provide the Sphynx HCM DNA test free of charge or heavily discounted for HCM positive Sphynx as well. If an HCM positive Sphynx is negative for this mutation, it might be invaluable in helping to identify the other mutation(s) causing HCM in the breed. Let’s continue to support her efforts, and show her that the Sphynx loving community is just as dedicated as our incredible breed.