Savannah Cats PK PRA Tests.
What does Savannah Cats PK PRA tests mean and what you, as a buyer should know about them. Always check with your breeder to make sure they are doing the tests and breeding responsibly. All our Savannah Cats are tested. Many buyers do not know why the tests are done and why breeders post the results? I am going to explain it here. Much of my information is credited to UCDavis website and Pet Coach
What is PK? Erythrocyte Pyruvate Kinase Deficiency
Erythrocyte Pyruvate Kinase Deficiency (PK Deficiency) is an inherited hemolytic anemia caused by insufficient activity of this regulatory enzyme which results in instability and loss of red blood cells. The anemia is intermittent, the age of onset is variable and clinical signs are also variable. Symptoms of this anemia can include: severe lethargy, weakness, weight loss, jaundice, and abdominal enlargement. This condition is inherited as an autosomal recessive.
Based on a survey of 38 breeds, the mutation responsible for PK deficiency has been found in significant frequency in Abyssinian, Bengal, Domestic Shorthair and Longhair, Egyptian Mau, La Perm, Maine Coon, Norwegian Forest, Savannah, Siberian, Singapura and Somali. Cats of these breeds are at higher risk of having PK deficiency or producing affected offspring; genetic screening for the mutation is recommended. A few breeds showed very low frequency of the mutation (less than 0.2%) and are low risk: Exotic Shorthair, Oriental Shorthair and Persian.
These are Your Results
N/N – No copiy of the PK Deficiency and cat is normal
N/K – 1 copy of PK Deficiency, cat is normal but is a carrier
K/K – 2 copies of PK deficiency, cat is or will be affected. Severity of symptoms cannot be predicted.
What do these results mean to a breeder/buyer. The goal in the Savannah Cat world is to only breed Savannah Cats that have been tested and are N/N. However, there are many breeders not testing the kittens at all. Which can and will lead to huge problems if you are buying a kitten from a breeder that doesn’t bother testing. No breeder should be selling a kitten for breeding purposes that is not N/N. However, prior to this test being available there were many really wonderful bloodlines that did carry 1 copy of the gene. The breeder should only breed an N/K cat to an N/N cat. If this is the case, they will test each kitten to assure if it is sold to a breeding home it is N/N. The N/K kittens will be sold as pets.
The N/K kittens are awesome and make wonderful pets as they only carry 1 copy and will not get the disease. You can not get a K/K kitten by breeding and N/K to an N/N cat. Ask your breeder if they are testing for the PK. This is where the problem comes in. Many people will buy 2 Savannah Cats and breed them without knowing either way. If you breed an N/K cat to an N/K cat it can create K/K kittens which could mean a short life for your kitten. At no time should a K/K cat ever be bred.
The Second Half of The Savannah Cats PK PRA Tests
Progressive retinal atrophy PRA is an issue that will lead to blindness. PRA is not very common in cats, although the Abyssinian breed seems to have a predilection. In Abyssinian, Somali and some Ocicat breeds, an inherited late-onset blindness condition has been identified and is characterized by progressive degeneration of the photoreceptors (rods and cones) in the retina. This disease has been designated “rdAc”. Cats affected with this form of blindness have normal vision at birth, with degeneration first detected by electroretinographic (ERG) exam at about seven months of age. Vision loss progresses slowly and is variable, with most cats becoming blind by usually 3-5 years of age. There is no treatment available for the condition. This is an autosomal recessive condition, thus the disease is not associated with gender and two copies of the mutation are required for the cats to lose their vision. Carriers, cats that have one copy of the mutation, are not affected and have normal vision. Written by UCDavis
[ezcol_1half]The eye is a very delicate, yet surprisingly durable organ. It consists of several layers. The cornea is a transparent layer that covers the front of the eye. The iris is the colored part of the eye and it is responsible for letting in more or less light. The lens gathers and ‘bends’ light in order to focus it on the retina. In between the cornea and lens is an area of fluid which bathes the lens and helps it focus. The retina lines the inside of the eye and converts light into signals which travel down the optic nerve to the brain. A large area between the lens and the retina contains a jelly-like fluid called ‘vitreous.’ The vitreous gives the eye its form and shape, provides nutrients, and removes waste products.[/ezcol_1half] [ezcol_1half_end]
Anatomy of the eye
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The retina
The retina is the structure affected in PRA. This important part of the eye receives the light gathered and focused by the other eye structures. It takes the light and essentially converts it into electrical nerve signals that the brain, via the optic nerve, interprets as vision. The retina contains photoreceptors, called rods and cones, which help the animal see in darkness (rods) and see certain colors (cones). Written by Petcoach
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What is PRA?
Normally, the photoreceptors in the retinas develop after birth to about 8 weeks of age. In PRA in cats, the photoreceptors develop in the kittens, but as the cat ages, the receptors degenerate. Progressive rod-cone degeneration (PRCD) is the most common form of PRA in cats, and starts with night blindness and progresses to total blindness at 3 to 5 years of age. The late onset of clinical signs in PRCD is particularly devastating to breeding programs. Because cats may have already been bred prior to the onset of symptoms.
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Can PRA be prevented?
PRA has been shown to have a genetic component. Kittens from parents who have no history of the disease have less risk of developing the disease. Affected animals should not be bred and should be spayed or neutered. The litter mates or parents of animals with PRA should also not be bred.
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| Test Result | CEP290 PRA-rdAc Status |
|---|---|
| N/N | Normal, cat does not have rdAc mutation* |
| N/rdAc | Carrier, cat has one copy of rdAc mutation. Breedings between carriers will be expected to produce 25% affected kittens. |
| rdAc/rdAc | Affected |
* This test only detects the mutation in the CEP290 gene known to cause PRA in Abyssinian, Somali, Ocicat and other breeds mentioned above.
| Test Result | CRX PRA-Rdy Status |
|---|---|
| N/N | Normal, cat does not have Rdy mutation** |
| N/Rdy | Affected, cat has one copy of the Rdy mutation. This cat will produce affected kittens 50% of the time when bred to a normal cat. 75% of the time when bred to another cat with one copy of the Rdy mutation. |
| Rdy/Rdy | Affected, cat will always produce affected kittens. |
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