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Progressive Retinal Atrophy, X-linked 2

Progressive Retinal Atrophy, X-linked 2 (XLPRA2) is an inherited eye disease in dogs that leads to early onset vision loss and potentially complete blindness, predominantly affecting male dogs.

Affected Genes: RPGR

Inheritance: X-Linked Recessive

Variant(canFam6):
chrX:20425883: A>

General Information: Progressive Retinal Atrophy, X-linked 2 (XLPRA2) manifests as a severe eye condition in dogs, characterized by early changes in the reflectivity and appearance of the tapetum—a structure behind the retina—detectable via veterinary eye exams as early as 8 weeks of age. This disease progresses to thinning of the retinal blood vessels, indicating reduced blood flow to the retina and leading to symptoms such as night blindness and a loss of peripheral vision. Although it affects both genders, male dogs are more frequently and severely impacted due to its X-linked inheritance pattern. Over time, affected dogs may experience a complete loss of vision, significantly impacting their ability to navigate their environment.

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 RPGR gene is critical for identifying carriers of Progressive Retinal Atrophy, X-linked 2 (XLPRA2). This disorder is inherited in an X-linked manner, meaning male dogs need only one copy of the mutated gene from their mother to be affected, while female dogs require two copies, one from each parent, to develop the disease. Thus, male offspring of a carrier female have a 50% chance of inheriting the disease. Genetic testing is essential for breeding decisions, particularly in identifying carrier females to prevent the breeding that might produce affected male pups. To minimize the occurrence of XLPRA2 and improve the overall health of future generations, it is recommended not to breed known carriers. While a normal genetic test result in the RPGR gene reduces the risk of XLPRA2, it does not exclude all forms of Progressive Retinal Atrophy due to other genetic variations, underscoring the importance of comprehensive genetic screening in breeding practices.

References:
Beltran WA, Hammond P, Acland GM, Aguirre GD. A frameshift mutation in RPGR exon ORF15 causes photoreceptor degeneration and inner retina remodeling in a model of X-linked retinitis pigmentosa. Invest Ophthalmol Vis Sci. 2006 47(4):1669-1681.

Zangerl B, Johnson JL, Acland GM, Aguirre GD. Independent origin and restricted distribution of RPGR deletions causing XLPRA. J Hered. 2007 98(5):526-530.