Sometimes I think kitten buyers think I am being overly dramatic about the genetic problems with the Burmese breed, or just trying to sell them one of my cats. Breaking news. I have a wait list. It's not about selling cats. I live in a chronic state of not enough kittens. There really really is a genetic problem with the American Burmese and it really really needs to be addressed. The breed was started with two cats almost 100 years ago. Common sense indicates its time for some fresh blood! I deeply appreciate the work of Doctor Lyons is doing and the fact she is communicating to the greater public about her findings. Below you can find a note where Dr.Lyons discuses the inbreeding problem with the Burmese breed. Its really worth reading.
Genetic Notes on the Burmese Cat Breed
27 June 2016
The Feline Genetics Laboratory, formerly of the University of California – Davis (UC Davis), now at the University of Missouri, has had long associations with Burmese breeders and veterinary researchers to define and identify the genetic mutations that cause various maladies in the Burmese breed. Many published studies (several listed below) have demonstrated that the Burmese breed has many genetic conditions, although the prevalence of these conditions is variable between countries. The Burmese in the USA are historically known for the autosomal recessive craniofacial defect that developed from the Contemporary lines of USA Burmese. Burmese carrying this condition have been identified in the UK, Europe and Australia due to the importation and use of the Contemporary lines. In addition, any other breed that has outcrossed to Contemporary Burmese has risk of the craniofacial defect. Recently, American Burmese breeders may be pursuing an organized project for heart disease.
In contrast, non - American Burmese are afflicted with several other conditions including GM2 gangliosidosis, hypokalemia, oral facial pain, diabetes, high triglycerides, a mid- line closure defect, and dermatosparaxis (stretchy skin, cutaneous asthenia, Ehlors- Danlos Syndrome). The genetic mutations for hypokalemia and GM2 gangliosidosis have been identified and like the craniofacial defect, the genetic test is available to assist breed management. Genetics studies regarding oral facial pain, diabetes, high triglycerides, flat-chested kittens, and dermatosparaxis are underway by our laboratory, in collaboration with other researchers, and independently by other researchers.
Our genetic studies have also included examining the population genetics of the different cat breeds and worldwide populations. In 2007, we published the first breed study that demonstrated that Singapura, Burmese and Birman had the lowest genetic diversity of the cat breeds we examined. A study between Singapura breeders and the UC Davis Veterinary Genetics Laboratory (VGL) supported our findings. Our recent studies demonstrate that the non-USA Burmese has as low genetic variation as the USA lines of Burmese. We strongly recommended outcrossing for all the Burmese breeds, including USA and non-USA Burmese.
Based on genetics, the Burmese breed originated from cats of Southeast Asia. Our genetic studies group cats from Thailand, Cambodia, Vietnam, Brunei and the Philippines as Southeast Asia cats. Historically, Burmese are considered to have origins from Thailand. Thus, random bred cats from Thailand and perhaps other regions of Southeast Asia are recommended as strong genetic candidates for outcrossing. Genetic tests for colors and health conditions can assist the selection of cats that may be the most advantageous for outcrossing. Other breeds with Southeast origins would also be of value to the Burmese outcrossing program, including Singapura, Bombay, and Burmese from any country. Burmilla and Asian have been crossed with Persian cats, which have western origins, thus, the use of these recent crossbred breed cats would add significant diversity, but of a different “racial” origins. Other Southeast Asian breeds include Siamese (and its breed derivatives), Korat, and Birman.
Because of our various genetic projects that include Burmese from different countries, we have been able to compare the genetics of the Burmese breed groups regionally. USA Burmese have high homozygosity (0.38), implying low genetic diversity (See attached report). The non-USA Burmese, which is a mixture of UK and Australian Burmese also have low diversity and high homozygosity (0.41), as compared to random bred cats (0.04) and other breeds. When we examine the Burmese diversity by plotting the genetic differences (termed multi-dimensional scaling (MDS), we find that the USA and non-USA Burmese do not cluster together and form independent genetic groups. The USA cats have a larger spread to their cluster as it includes Contemporary and Traditional lines of Burmese. Thus, Burmese breeders may consider crossing the Burmese cats from different countries to help improve genetic diversity.
Other genetic conditions in Southeast Asian cats include different forms of gangliosidosis in Korat and Siamese cats and pyruvate kinase deficiency in Singapura. Some Birman lines may have a susceptibility to FIP.
Overall, we have more genetic projects concerning Burmese than for any other breed and our various genetic studies have repeatedly demonstrated that Burmese, regardless of country, have amongst the lowest genetic diversity of all cat breeds. An organized and multi-faceted outcrossing program for the breed is highly recommended which includes the use of genetic testing and outcrossing to different populations and breeds.
Leslie A. Lyons, PhD
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