For autosomal recessive disorders, cats with two copies of the variant are at risk of developing the condition. Cats with one copy of the variant are considered carriers and are usually not at risk of developing the disorder. However, carriers of some complex variants grouped in this category may be associated with a low risk of developing the disorder. Individuals with one or two copies may pass the disorder-associated variant to their kittens if bred.
At risk cats are highly likely to show signs of this disease in their lifetime.
Partner with your veterinarian to make a plan regarding your cat’s well-being, including any insights provided through genetic testing. If your pet is at risk or is showing signs of this disorder, then the first step is to speak with your veterinarian.
Progressive Retinal Atrophy (PRA), in the rdAc form, follows the typical pattern where functional loss of rod photoreceptors occurs first, followed by loss of function of cone photoreceptors. Age of onset for this form of PRA is typically late, with the first ophthalmoscopic signs of affected cats seen at one to two years of age. These signs may include a slight grayish discoloration along the central fundus progressing to the entire tapetal fundus, a hyper-reflective tapetum and attenuated blood vessels. The disorder is progressive, causing increasing levels of vision loss and eventual blindness by three to seven years of age. Early indications of visual compromise may include disorientation and lack of awareness of changes to the surroundings, especially in low light conditions. Affected cats may accidentally bump into things and become more vocal.
Although this condition results in vision loss and eventual blindness, many cats adapt remarkably well to vision loss. Owners may find that it is helpful to keep the cat's main environment as stable as possible (avoid moving food bowl, water bowl, litter box, furniture, etc.) to help them navigate as vision worsens. To avoid startling the cat, speak to and stroke the cat before picking them up and set them back down in an area where they can easily orient themselves, such as next to their food bowl. Use toys that make a noise (ex. balls with bells) for play. Caretakers should take precautions to protect the cat from threats it cannot visually detect (ex. stairs, pools, moving vehicles). Owners should also be advised that their cat cannot safely roam freely outdoors due to its compromised vision.
There are many responsibilities to consider when breeding cats. Regardless of test results it is important that your cat is in good general health and that you are in a position to care for the kittens if new responsible owners are not found. For first time or novice breeders, advice can be found at most cat registry websites.
This disease is autosomal recessive meaning that two copies of the mutation are needed for disease signs to be shown. A carrier cat with one copy of the PRA mutation can be safely bred with a clear cat with no copies of the PRA mutation. About half of the kittens will have one copy (carriers) and half will have no copies of the PRA mutation. Kittens in a litter which is expected to contain carriers should be tested prior to breeding. Carrier to carrier matings are not advised as the resulting litter may contain affected kittens. Please note: It is possible that disease signs similar to the ones caused by the PRA mutation could develop due to a different genetic or clinical cause.
All coordinates reference FelCat9.0
Menotti-Raymond, M., David, V. A., Schäffer, A. A., Stephens, R., Wells, D., Kumar-Singh, R., O’Brien, S. J., & Narfström, K. (2007). Mutation in CEP290 discovered for cat model of human retinal degeneration. Journal of Heredity, 98(3), 211–220. View the article