Progressive Retinal Atrophy (GR_PRA1 and GR_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 GR_PRA1 and GR_PRA2.
Search Keywords
PRA1
PRA2

Phenotype: Progressive retinal atrophy is characterized by bilateral degeneration of the retina resulting in progressive vision loss leading to total blindness. Clinical signs of GR_PRA1 appear around 6 years of age. Clinical symptoms of GR-PRA2 appear around 4 years of age.

Mode of Inheritance: Autosomal recessive

Alleles:

N = Normal
GR_PRA1 = Golden Retriever progressive retinal atrophy (variant 1)
GR_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/GR_PRA1 or N/GR_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 GR_PRA1/GR_PRA1 or GR_PRA2/GR_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)

Price

$50 one test per animal
$30 as additional test (same animal)

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 GR_PRA1 and GR_PRA2. GR_PRA1 results from a mutation in the SLC4A3 gene and accounts for over 60% of diagnosed Golden Retrievers. GR_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 GR_PRA1 appear around 6 years of age. Clinical symptoms of GR-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 GR_PRA1  (that is N/N for GR_PRA2) with a carrier of GR_PRA2 (that is N/N for GR_PRA1) will not produce affected animals.

Testing for GR_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 GR_PRA1 and 2 is recommended for Golden Retrievers and Golden Doodles. GR_PRA2 has been reported at low frequency in Labrador Retrievers, but an extensive survey of the US population has yet to be investigated.

Turnaround Time
3-6 business days

Species

Dog

Type of Test

Results Reported As

 

GR_PRA 1

Test Result Golden Retriever Progressive Retinal Atrophy 1
N/N No copies of the GR_PRA1 mutation present. Dog is normal.
N/GR_PRA1 1 copy of the GR_PRA1 mutation. Dog is normal but is a carrier.
GR_PRA1/ GR_PRA1 2 copies of the GR_PRA1 mutation. Dog is affected.

 

GR_PRA2

Test Result Golden Retriever Progressive Retinal Atrophy 2
N/N No copies of the GR_PRA2 mutation. Dog is normal.
N/GR_PRA2 1 copy of the GR_PRA2 mutation. Dog is normal but is a carrier.
GR_PRA2/ GR_PRA2 2 copies of the GR_PRA2 mutation. Dog is affected.
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

License Info

The GR_PRA2 test is performed under license through Animal Health Trust, Newmarket, England. VGL is not authorized to offer this test in Europe.