Progressive Retinal Atrophy (PRA1 and PRA2) in Golden Retrievers

Quick Summary

Progressive retinal atrophy (PRA) is characterized by bilateral degeneration of the retina resulting in progressive vision loss leading to total blindness. More than one form of PRA affects Golden Retrievers, and causal mutations in three distinct genes have been identified; two of those mutations lead to PRA1 and PRA2.

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Phenotype: Progressive retinal atrophy is characterized by bilateral degeneration of the retina resulting in progressive vision loss leading to total blindness. Clinical signs of PRA1 appear around 6 years of age. Clinical symptoms of PRA2 appear around 4 years of age.

Mode of Inheritance: Autosomal recessive

Alleles:

N = Normal
PRA1 = Golden Retriever progressive retinal atrophy (variant 1)
PRA2 = Golden Retriever progressive retinal atrophy (variant 2)

Breeds appropriate for testing: Golden Retriever, Golden Doodle, Labrador Retriever

Explanation of Results:

  • Dogs with N/N genotype are not expected to develop either of these two forms of Golden Retriever progressive retinal atrophy and cannot transmit these progressive retinal atrophy variants to their offspring.
  • Dogs with N/PRA1 or N/PRA2 genotype are not expected to develop either of these two forms of Golden Retriever progressive retinal atrophy, but are carriers. They may transmit a Golden Retriever progressive retinal atrophy variant to 50% of their offspring. Matings between two carriers of the same variant (e.g. N/GR_PRA1 x N/GR_PRA1) are predicted to produce 25% of puppies affected by that form of progressive retinal atrophy. Matings between two carriers of the different variants (N/GR_PRA1 x N/GR_PRA2) will not produce affected offspring.
  • Dogs with PRA1/PRA1 or PRA2/PRA2 are expected to develop progressive retinal atrophy. They will transmit respective progressive retinal atrophy variants to all of their offspring.

Results of this test can be submitted to the OFA (Orthopedic Foundation for Animals)

Turnaround Time
At least 15 business days; may be delayed beyond 15 business days if sample requires additional testing, or a new sample is requested.
Price

$55 single test per animal ($5 discount on 3 or more dogs)
$25 as additional health test on same animal

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Additional Details

More than 20 mutations have been identified that result in canine progressive retinal atrophy (PRA). The condition is characterized by bilateral degeneration of the retina resulting in progressive vision loss leading to total blindness. Golden Retrievers are affected by more than one form of PRA with mutations in three distinct genes having been identified. Two of such mutations are known as PRA1 and PRA2. PRA1 results from a mutation in the SLC4A3 gene and accounts for over 60% of diagnosed Golden Retrievers. PRA2 results from a mutation in the TTC8 gene and accounts for 30% of Golden Retrievers diagnosed with PRA. Both mutations are autosomal recessive thus two copies of the same affected gene must be present for the disease to be observed and both males and females are equally affected. Presence of one copy of each affected genes in the same dog will not cause blindness. Clinical signs of PRA1 appear around 6 years of age. Clinical symptoms of PRA2 appear around 4 years of age. Breeding two carriers with the same mutation is predicted to produce 25% affected puppies and 50% carriers. Mating a carrier of PRA1  (that is N/N for PRA2) with a carrier of PRA2 (that is N/N for PRA1) will not produce affected animals.

Testing for PRA1 and 2 assists owners and breeders in identifying affected and carrier dogs. Breeders can use results from the tests as a tool for selection of mating pairs to avoid producing affected dogs. Genetic testing for PRA1 and 2 is recommended for Golden Retrievers and Golden Doodles. PRA2 has been reported at low frequency in Labrador Retrievers, but an extensive survey of the US population has yet to be investigated.

Search Keywords
PRA1
PRA2
Type of Sample
Cytology Brush - supplied by VGL at no additional charge (PREFERRED)
Mini mascara brushes - supplied by owner (click for accepted type)
Interdental/GUM brushes - supplied by owner (click for accepted types)

Species

Dog

Breed

Golden Retriever Goldendoodle Labrador Retriever
Type of Test
Health
Results Reported As

Golden Retriever Progressive Retinal Atrophy 1

Test Result Progressive Retinal Atrophy (PRA1)
N/N Normal. Dog does not have the variant associated with PRA1 found in Golden Retrievers.
N/PRA1 Carrier. Dog has one copy of the variant associated with PRA1 found in Golden Retrievers.
PRA1/ PRA1 Affected. Dog has two copies of the variant associated with PRA1 found in Golden Retrievers and will likely develop the disease.

 

Golden Retriever Progressive Retinal Atrophy 2

Test Result Progressive Retinal Atrophy (PRA2)
N/N Normal. Dog does not have the variant associated with PRA2 found in Golden Retrievers.
N/PRA2 Carrier. Dog has one copy of the variant associated with PRA2 found in Golden Retrievers.
PRA2/ PRA2 Affected. Dog has two copies of the variant associated with PRA2 found in Golden Retrievers and will likely develop the disease.
References

Downs, L.M., Wallin-Håkansson, B., Boursnell, M., Marklund, S., Hedhammar, Å., Truvé, K., Hübinette, L., Lindblad-Toh, K., Bergström, T., & Mellersh, C.S. (2011). A frameshift mutation in golden retriever dogs with progressive retinal atrophy endorses SLC4A3 as a candidate gene for human retinal degenerations. PLoS One, 6(6):e21452. doi: 10.1371/journal.pone.0021452

Downs, L.M., Wallin-Håkansson, B., Boursnell, M., Bergström, T., & Mellersh, C.S. (2014). A novel mutation in TTC8 is associated with progressive retinal atrophy in the golden retriever. Canine Genetics and Epidemiology 1:4. doi: 10.1186/2052-6687-1-4

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