CNGA1-PRA test Code 305
PRA Mutation in Shelties Identified:
Researchers from Norwegian University of Life Sciences (Wiik et al.) have identified a novel mutation in CNGA1 gene that causes early onset PRA in Shetland Sheepdogs . OptiGen is pleased to provide the Shetland Sheepdog community with a DNA test, CNGA1-PRA, for this important disease.
Brief Description of PRA in Shelties:
PRA in Shelties is clinically indistinguishable from PRA in other breeds. As in other forms of PRA, it is characterized by visual impairment due to degeneration of the photoreceptors in the retina, eventually leading to blindness. Often the first sign of PRA apparent to an owner is night blindness however a veterinary ophthalmologist may detect the disease at an earlier stage of disease during routine clinical examination. Over time, the disease progresses to advanced PRA in which vision loss is evident even at bright light levels. The average age of clinical diagnosis in Shelties with CNGA1-PRA was reported to be 5 years  however there may be variation in the age of PRA-symptom onset.
CNGA1-PRA Inheritance in Shelties:
CNGA1-PRA is inherited as an autosomal recessive disease in Shelties which means that dogs will only develop this form of PRA when they inherit two copies of mutant DNA, one from each parent. Carriers of only one copy of the mutation will not develop the disease.
Other forms of PRA in Shelties:
Unfortunately there are other forms of PRA in Shelties that are not detected by this test. The breed suffers from at least one, and possibly more variants of PRA that are not yet characterized. Among those unidentified mutations is Slow Progressing Retinopathy (SPR). SPR is a form of retinal degeneration that progresses more slowly and does not cause such obvious visual impairment as does CNGA1-PRA . This test does not detect SPR. Please contact OptiGen if you own or know any PRA-affected Shelties (or any other pedigreed dog diagnosed with PRA) to learn about OptiGenís PRA Research and Free DNA testing program.
Page last updated February 08, 2017
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