Progressive Retinal Atrophy, Rod-Cone Dysplasia 4
Affected Genes: C2orf71
Inheritance: Autosomal Recessive
Variant(canFam6):
chr17:22701624: 1 bp insertion G
Breed: Aussiedoodle
Australian Cattle Dog
Australian Labradoodle
Australian Stumpy Tail Cattle Dog
Bernedoodle
Bordoodle
Cavapoo
Cavapoochon
Cockapoo
Danoodle
English Setter
Goldendoodle
Gordon Setter
Irish Red and White Setter
Irish Setter
Irishdoodle
Japanese Spitz
Labradoodle
Llewelyn Setter
Maltipoo
Miniature Poodle
Newfypoo
Old Danish Pointer
Polish Lowland Sheepdog
Poodle
Schnoodle
Sheepadoodle
Small Munsterlander
Standard Poodle
Tibetan Terrier
Toy Poodle
Yorkiepoo
General Information: Progressive Retinal Atrophy, Rod-Cone Dysplasia 4 (PRA-RCD4) is a late-onset inherited eye disorder affecting dogs, typically manifesting between the ages of 7 and 12. Affected dogs initially exhibit changes in the reflectivity and appearance of the tapetum, a structure behind the retina, detectable during a veterinary eye exam. As the disease progresses, it leads to the thinning of the retinal blood vessels, indicating reduced blood flow to the retina. Early symptoms include vision loss in low light conditions (night blindness) and a reduction in peripheral vision, which gradually worsens to complete blindness in most affected dogs. Monitoring for these signs and early veterinary intervention are crucial to managing the dog's quality of life as the condition progresses.
How to Read Your Dog's Test Results for this Genetic Variant:
Two Variants Detected: Dog Likely Affected
One Variant Detected: Dog Unlikely Affected
No Variants Detected: No Effect
Gene / Testing Information: Genetic testing of the C2ORF71 gene can determine whether a dog is a carrier of PRA-RCD4, an autosomal recessive disorder. To develop PRA-RCD4, a dog must inherit two copies of the mutated gene, one from each parent. Carrier dogs, which possess only one copy of the mutation, do not exhibit symptoms but can pass the gene to their offspring. When two carriers are bred together, there is a 25% chance of each pup inheriting the disease and a 50% chance of being a carrier. Reliable genetic testing is essential for making informed breeding decisions to prevent the birth of affected puppies. As PRA-RCD4 symptoms do not appear until adulthood, it is critical to perform genetic testing before breeding. To avoid the potential of producing affected pups and to eliminate the mutation from breeding lines, it is recommended not to breed two known carriers together. Although a normal C2ORF71 test result indicates no increased risk for PRA-RCD4, it does not exclude other forms of progressive retinal atrophy caused by mutations in different genes.
References:
Djajadiningrat-Laanen SC, Boevé MH, Stades FC, van Oost BA. Familial non-rcd1 generalised retinal degeneration in Irish setters. J Small Anim Pract. 2003 44(3):113-116.
Downs LM, Bell JS, Freeman J, Hartley C, Hayward LJ, Mellersh CS. Late-onset progressive retinal atrophy in the Gordon and Irish Setter breeds is associated with a frameshift mutation in C2orf71. Anim Genet. 2013 44(2):169-177.
Downs LM, Hitti R, Pregnolato S, Mellersh CS. Genetic screening for PRA-associated mutations in multiple dog breeds shows that PRA is heterogeneous within and between breeds. Vet Ophthalmol. 2014 17(2):126-130.
Miyadera K, Acland GM, Aguirre GD. Genetic and phenotypic variations of inherited retinal diseases in dogs: the power of within- and across-breed studies. Mamm Genome 2012 23(1-2):40-61.