Early Retinal Degeneration

Other Names: Progressive retinal atrophy-erd, Retinal photoreceptor dysplasia, ERD
Affected Genes: STK38L
Inheritance: Autosomal Recessive
Mutation: chr27:20447905-20447906 (canFam3): 229 bp insertion; chr27:20447906-20447920 (canFam3): 15 bp duplication (dup GGAAACAGAGTTCTT)
Breed(s): Norwegian Elkhound

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Common Symptoms

Early retinal degeneration (ERD) is an inherited eye disease affecting dogs. ERD usually presents at 3 to 10 weeks of age as general poor vision and night blindness. Affected puppies may appear to move more cautiously than littermates and have a tendency to bump into objects. ERD occurs as a result of abnormal development and degeneration of Photoreceptor Cells (Rod and Cone Cells) of the Retina, which are responsible for sensing light and transmitting signals to the brain, resulting in vision. The disease initially progresses rapidly, but progression slows after 6 months of age. Dogs become totally blind between 12 to 18 months of age. Between 4-5 years of age, affected dogs also develop cataracts.

Testing Tips

Genetic testing of the STK38L gene will reliably determine whether a dog is a genetic Carrier of early retinal degeneration. Early retinal degeneration 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 STK38L gene mutation. Reliable genetic testing is important for determining breeding practices. 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. Dogs that are not carriers of the mutation have no increased risk of having affected pups with this disease. However, because there are multiple types of retinal degeneration or Atrophy caused by mutations in other genes, a normal result in STK38L does not exclude retinal degeneration or atrophy in a pedigree.

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

  • Acland GM, Aguirre GD. Retinal degenerations in the dog: IV. Early retinal degeneration (erd) in Norwegian elkhounds. Exp Eye Res. 1987 Apr;44(4):491-521. [PubMed: 3496233]
  • Berta ÁI, Boesze-Battaglia K, Genini S, Goldstein O, O'Brien PJ, Szél Á, Acland GM, Beltran WA, Aguirre GD. Photoreceptor cell death, proliferation and formation of hybrid rod/S-cone photoreceptors in the degenerating STK38L mutant retina. PLoS One. 2011; 6(9):e24074. [PubMed: 21980341]
  • Goldstein O, Kukekova AV, Aguirre GD, Acland GM. Exonic SINE insertion in STK38L causes canine early retinal degeneration (erd). Genomics. 2010 Dec; 96(6):362-8. [PubMed: 20887780]