PRA-rdAc - Progressive Retinal Atrophy
What is PRA-rdAc ?
APR-rdac (progressive retinal atrophy) is an inherited genetic eye disease that develops in cats between 3-5 years of age. This disease has been observed in many breeds of cat: Siamese (45%), Abyssinian (34%), Somali, Cornish Rex, Oriental (55%), Bengal, Balinese, Tonkinese, Peterbald, Singapura, Munchkin, Ocicat, American wirehair, American curl.
APR-rdac causes degeneration of the retina of the eye.
At the age of 1.5 to 2 years, the retina of the cat’s eye with APR-rdac is still normal.
From 3 to 5 years, we observe an alteration of the rods.
The degeneration of the cones of the eye (atrophy of the retina) causing blindness of the cat and usually appears between the age of 4 to 8 years.
4 stages of PRA-rdac evolution have been described according to Padnick-Silver et al. Invest Ophthalmol Vis. Sci. 47.8 (2006): 3683-689
PRA-rdAc genetic test
The DNA test for the detection of APR-rdac can be performed from the age of 2 months. Like all genetic tests, this test is very reliable.
The test is carried out using a buccal swab, which is quick and easy to perform.Here is the list of the different types of samples that are accepted for this test :
- Buccal swab
- Blood in EDTA tube
- Blood in dry tube
Screening and interpretation of results
PRA-rdac in cats is due to a mutation in the CEP290 gene. The modification of a base pair in the intron 50 (IVS50 + 9T ˃ G) of this gene leads to the modification of the transcription of the mRNA.
This mutation is hereditary according to an autosomal recessive mode with complete penetrance.
The test does not allow to determine the severity of the PRA-rdac, nor the age of appearance of the symptoms.
Available breeds for the test : PRA-rdAc – Progressive Retinal Atrophy
The following breeds are recognized :
- American Curl
- American Wirehair
- Cornish Rex
Understanding results of the test : PRA-rdAc – Progressive Retinal Atrophy
Gene Mutation : CEP290 IVS50 + 9T>G
Heredity : autosomal recessive (more information)
Penetrance : complete (more information)
|Test result||PRA-rdAc – Progressive Retinal Atrophy status (CEP290 IVS50 + 9T>G)||Health status|
|N/N||No copy of the PRA-rdAc mutation||Animal is normal (clear)|
|N/PRA-rdAc||1 copy of the PRA-rdAc mutation||Animal is normal (clear)|
|PRA-rdAc/PRA-rdAc||2 copies of the PRA-rdAc mutation||Animal is, will or could be affected|
Cross table of the test : PRA-rdAc – Progressive Retinal Atrophy
|Mother N/N||Mother N/PRA-rdAc||Mother PRA-rdAc/PRA-rdAc|
|Father N/N||100% N/N||50% N/N|
|Father N/PRA-rdAc||50% N/N|
|Father PRA-rdAc/PRA-rdAc||100% N/PRA-rdAc||50% N/PRA-rdAc|
Certificate example for the test : PRA-rdAc – Progressive Retinal Atrophy
Click on the example certificate below to open it.
Menotti-Raymond M, VA Davis, AA Schaffer et al. Mutation in CEP290 discovered for cat model of human retinal degeneration. Journal of Heredity 98(3):211-220 (2007).
Narfström K., David V., Jarret O., Beatty J., Barrs V., Wilkie D., O’Brien S. and Menotti-Raymond M. Retinal degeneration in the Abyssinian and Somali cat (rdAc):correlation between genotype and phenotype and rdAc allele frequency in two continents. Veterinary Ophthalmology (2009) 12, 5, 285-291