Siamese and Orientals
A breeder in England recently became concerned when her six year old fawn Oriental started to lose his sight. After he tested positive for Progressive Retinal Atrophy (PRA), she had all her cats DNA tested and was horrified to find how many were carriers (five out of six).
She persuaded other breeders to test with results that she describes as "frightening". The carriers were not confined to just some Oriental lines, but included unrelated pure Siamese. It has also been recorded in Abyssinians.
Progressive Retinal Atrophy
PRA is caused by a recessive gene, which means that both parents must be carriers for the cat to be affected.
PRA is one of many conditions for which DNA tests can be done on a buccal swab, which is completely non-invasive for the cat. The information I was sent said that the Feline Advisory Bureau at Langford (England) does it at a reasonable cost. We urge all breeders to be aware of possible genetic problems and to test for them.
It seemed apt to highlight communication from Jane Goble here. Although her letter specifically concerns Burmese, it should be remembered that many breeds have inherited defects which DNA testing can help to eradicate.
Dear Burmese breeders,
You may be aware that the Burmese can carry the gene that causes hypokalaemia - referred to as HK (a potassium deficiency).
It is breed specific and can occur in breeds where Burmese are allowed as an outcross.
Burmese breeders in South Africa (before my time) worked really hard at eliminating the carrier cats from the lines in this country but as it is a recessive gene it can lurk around for many generations until 2 carrier cats are mated and a hypokalaemic kitten is produced.
They did not have the benefit of DNA testing to diagnose carrier cats. There are also now many cats that have been imported and we do not know their backgrounds.
The youtube clip will show how awful it is for the affected kitten. It is often very difficult to diagnose as many of the vets are not aware of hypokalaemia. It can be many months before the affected kitten starts getting the daily potassium supplements. As you will see from the clip the affected kittens are usually only diagnosed at 4-5 months, just after they have gone to their new homes
There is now a DNA test that can test the carrier status of Burmese.
Should you test your cat & find that it is a carrier you will know not to mate it with another cat that is a carrier. In this way it is possible in a couple of generations to breed, test & keep non carrier kittens to continue your breeding program with. The most practical way would be to test adult cats within your breeding program. If they are not carriers then you know that any offspring that you have kept will not be carriers. If one of them is a carrier then it is necessary to test the offspring to ascertain whether or not the carrier gene has been passed on to them. I have attached the link to the Veterinary Genetics Laboratory in California.
There are clear instructions on collecting buccal swab samples - it is a user friendly site in terms of logging your cats' de-tails, paying for the tests and receiving the submission forms. Burmese breeders internationally are embarking on testing programs within their catteries to breed this carrier gene out. I would really encourage you to join in the effort to eliminate this condition from our breed.
Should you have any questions I will do my best to assist.