Progressive Retinal Atrophy (Basenji Type)
Affected Genes: SAG
Inheritance: Autosomal Recessive With Variable Expressivity
Variant(canFam6):
chr25:45338675: T>C
Breed: Basenji
General Information: Progressive Retinal Atrophy (PRA) in Basenjis is a genetic eye condition that typically begins affecting dogs around 5 years of age with initial changes observable in the tapetum—a reflective structure behind the retina—during a veterinary eye exam. As the disease progresses, retinal blood vessels thin by the ages of 6 or 7, indicating reduced blood flow to the retina and leading to symptoms such as night blindness and loss of peripheral vision. The progression and severity of the disease can vary, but many dogs eventually experience complete vision loss, although some may retain daytime vision for several years or even for the remainder of their lives. This condition profoundly affects a dog's ability to see in low-light conditions initially and can progress to full blindness, severely impacting their quality of life.
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 SAG gene in Basenjis provides critical information on whether a dog is a carrier of Progressive Retinal Atrophy (PRA) (Basenji Type), which is inherited in an autosomal recessive manner. For a Basenji to be affected by this form of PRA, it must inherit two copies of the mutated gene, one from each parent. Carriers, having only one copy of the mutation, typically do not exhibit symptoms but can produce affected offspring if bred with another carrier. Breeding decisions should be informed by genetic testing to prevent mating between carriers, as each offspring from such a pairing has a 25% chance of being affected and a 50% chance of being a carrier. By avoiding the breeding of carriers, breeders can significantly reduce the incidence of this debilitating eye disease in the breed, ensuring the production of healthier future generations. Additionally, it's important to note that a normal result in the SAG gene testing does not eliminate the risk of other types of PRA caused by different genetic mutations.
References:
Goldstein O, Jordan JA, Aguirre GD, Acland GM. A non-stop S-antigen gene mutation is associated with late onset hereditary retinal degeneration in dogs. Mol Vis. 2013 19:1871-1884.