Congenital Stationary Night Blindness

Other Names: Hereditary retinal dystrophy, Leber congenital amaurosis, Retinal pigment epithelial dystrophy, CSNB, LCA
Affected Genes: RPE65
Inheritance: Autosomal Recessive
Mutation: chr6:76893207-76893210 (canFam3): 4 bp deletion (del AAGA)

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Common Symptoms

Congenital Stationary Night Blindness (CSNB) is a rare inherited eye disease affecting Briards. CSNB causes slowly progressive degeneration of the Retina, which is the part of the eye that collects visual information and communicates with the brain. Loss of night vision is first noticed in affected dogs as early as 5 weeks of age, while ophthalmologic changes are not visible until affected dogs are 2-3 years of age. Light brown patches form on the surface of the retina. These patches increase in size and coalesce over time until the entire retina is affected. Affected dogs may be reluctant to move in low light, and over time, day vision is also lost.

Breed-Specific Information for the Briard

The Mutation of the RPE65 gene associated with congenital stationary night blindness has been identified in Briards. Though the frequency in the overall Briard population is unknown, in one study of 108 Briards from the United States, 10.2% were carriers of the mutation. In a second study of 173 Briards from the Czech Republic, Poland, Hungary, and Slovakia, 11% were carriers of the mutation.

Testing Tips

Genetic testing of the RPE65 gene in Briards will reliably determine whether a dog is a genetic Carrier of congenital stationary night blindness. Congenital Stationary Night Blindness is inherited in an Autosomal Recessive manner in dogs meaning that they must receive two copies of the mutated gene (one from each parent) to develop the disease. In general, carrier dogs do not have features of the disease but when bred with another carrier of the same Mutation, there is a risk of having affected pups. Each pup that is born to this pairing has a 25% chance of inheriting the disease and a 50% chance of inheriting one copy and being a carrier of the RPE65 gene mutation. Reliable genetic testing is important for determining breeding practices. Because symptoms may not appear until adulthood, genetic testing should be performed before breeding. In order to eliminate this mutation from breeding lines and to avoid the potential of producing affected pups, breeding of known carriers to each other is not recommended. Briards that are not carriers of the mutation have no increased risk of having affected pups.

There may be other causes of this condition in dogs and a normal result does not exclude a different mutation in this gene or any other gene that may result in a similar genetic disease or trait.

References

  • Aguirre GD, Baldwin V, Pearce-Kelling S, Narfström K, Ray K, Acland GM. Congenital stationary night blindness in the dog: common mutation in the RPE65 gene indicates founder effect. Mol Vis. 1998 Oct 30; 4:23. [PubMed: 9808841]
  • Bechyňová R, Dostál J, Stratil A, Jílek F, Horák P. Mutation in the RPE65 gene causing hereditary retinal dystrophy in the Briard dogs: application of a new detection method. Czech J Anim Sci., 2008; 53(4): 176–179. [not in PubMed]
  • Hernández M, Pearce-Kelling SE, Rodriguez FD, Aguirre GD, Vecino E. Altered expression of retinal molecular markers in the canine RPE65 model of Leber congenital amaurosis. Invest Ophthalmol Vis Sci. 2010 Dec; 51(12):6793-802. [PubMed: 20671290]
  • Narfström K, Wrigstad A, Björn E, Nilsson SEG. Hereditary retinal dystrophy in the Briard dog: Clinical and hereditary characteristics. Vet Comp Ophthalmol, 1994; 4:85-92. [not in PubMed]
  • Veske A, Nilsson SE, Narfström K, Gal A. Retinal dystrophy of Swedish briard/briard-beagle dogs is due to a 4-bp deletion in RPE65. Genomics. 1999 Apr 1; 57(1):57-61. [PubMed: 10191083]
  • Wrigstad A, Narfström K, Nilsson SEG. Slowly progressive changes of the retina and retinal pigments epithelium in Briard dogs with hereditary retinal dystrophy. A morphologic study. Doc Ophthalmol. 1194; 87:337-354. [PubMed: 7851218]