Progressive Retinal Atrophy (PRA Rdy) (Abyssinian)

Quick Summary

This progressive retinal atrophy is an inherited, rare form of early-onset blindness seen in Abyssinian and Somali cats. Affected cats have retarded development and degeneration of photoreceptor cells, which leads to blindness by 7 weeks of age.

Phenotype: Cats affected with this rare form of early-onset blindness have retarded development and degeneration of photoreceptor cells, which leads to blindness by 7 weeks of age.

Mode of Inheritance: Autosomal dominant

Alleles: N = Normal, Rdy = Progressive retinal atrophy (CRX mutation-associated)

Breeds appropriate for testing: Abyssinian, Somali

Explanation of Results:

  • Cats with N/N genotype will not have CRX/Rdy progressive retinal atrophy and cannot transmit this progressive retinal atrophy variant to their offspring.
  • Cats with N/Rdy genotype will have CRX/Rdy progressive retinal atrophy, an untreatable condition leading to early-onset blindness. They will transmit this progressive retinal atrophy variant to 50% of their offspring. Matings between two N/Rdy cats are predicted to produce 75% kittens affected by this CRX/Rdy form of progressive retinal atrophy.
  • Cats with Rdy/Rdy genotype will have CRX/Rdy progressive retinal atrophy, an untreatable condition leading to early-onset blindness. They will transmit this progressive retinal atrophy variant to all of their offspring.
Price

$40 one test per animal

Also available as part of the following packages:

Additional Details

A form of blindness called “rod cone dysplasia”, or “Rdy” has been identified in Abyssinian and Somali cats. This progressive retinal atrophy differs from the "rdAc" (CEP290 mutation) progressive retinal atrophy. The mutation underlying "Rdy" is a single base pair deletion in a different gene, CRX, which results in a defective protein that is critical for eye development. Cats carrying one copy of this mutation have retarded development and degeneration of photoreceptor cells, which leads to early-onset blindness by 7 weeks of age. Current information suggests that the “Rdy” mutation is restricted to the Abyssinian and Somali breeds. The “Rdy” mutation is inherited as a dominant trait: cats that have one or two copies of the mutation will be affected. The Rdy mutation is rare.

To assist owners and breeders in identifying affected and carrier cats, the VGL offers DNA tests for the two mutations known to cause the two different forms of PRA in cats - rdAc (CEP290) and Rdy (CRX). Breeders can use these tests as tools to avoid breeding two carriers of rdAc which would produce 25% affected offspring, or to test for the presence of “Rdy” in the CRX gene of suspected affected cats.

Since both forms of blindness are found in the Abyssinian breed, all associated breeds may have a concern for these diseases. A novel form of blindness occurs in the Bengal cat, and a separate causative mutation has been identified (a genetic test for the Bengal-specific PRA is available here). However, since Bengal cats have had Abyssinian breedings in their ancestry, genetic testing for rdAc and Rdy may also be warranted in some Bengal lines.

 

Note: The test offered on this page only detects the mutation in the CRX gene known to cause "Rdy" progressive retinal atrophy in Abyssinian and Somali breeds. To view the DNA test for the mutation in the CEP290 gene (rdAc), click here.
Turnaround Time
2-6 business days
Type of Sample

Species

Cat

Type of Test

Results Reported As
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, or 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.
References

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. doi: 10.1093/jhered/esm019

Menotti-Raymond, M., David, V.A., Pflueger, S., Roelke, M.E., Kehler, J., O'Brien, S.J., & Narfström, K. (2009). Widespread retinal degenerative disease mutation (rdAc) discovered among a large number of popular cat breeds. The Veterinary Journal, 186(1), 32-38. doi: 10.1016/j.tvjl.2009.08.010

Menotti-Raymond, M., Deckman, K.H., David, V., Myrkalo, J., O'Brien, S.J., & Narfström, K. (2010). Mutation discovered in a feline model of human congenital retinal blinding disease. Investigative Ophthalmology & Visual Science, 51(6), 2852-2859. doi: 10.1167/iovs.09-4261