Progressive Retinal Atrophy-Cone-Rod Dystrophy (crd1-PRA)
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Price: $45.00Price: £40.00
Breeds: Chihuahua, Curly-Coated Retriever, Dachshund, English Bulldog, English Springer Spaniel, Field Spaniel, French Bulldog, Longhaired Miniature Dachshund, Miniature Dachshund, Miniature English Bulldog, Miniature Olde English Bulldog, Miniature Smooth Dachshund, Miniature Wirehaired Dachshund, Mixed Breed, Olde English Bulldogge, Sprocker Spaniel, Sprockerpoo, Unspecified, Unspecified Breed, Welsh Springer Spaniel, Wirehaired Dachshund
Description
Cord1-PRA or crd1-PRA is a type of Progressive Retinal Atrophy (PRA). PRA is a general term for a group of diseases that cause the degeneration of the retina, which eventually leads to a loss of vision. Cord1-PRA stands for Cone-Rod Dystrophy-PRA. Cord1-PRA is a genetic disorder associated with a recessive mutation. Recessive mutations are mutations that can be passed from either parent and require two copies of the gene to show symptoms.
The mutation occurs in the RPGRIP1 gene. This gene codes for a protein that is important to photoreceptor cells in the eye. Like many forms of PRA, Cord1-PRA is breed-specific and is known to occur in Miniature Dachshunds and English Springer Spaniels.
Cone-rod dystrophy first affects the cones in the retina, which are the photoreceptor cells responsible for detecting bright light or daylight. Rods, or the low-light photoreceptor cells, begin degenerating afterwards. This is different than other forms of PRA (such as prcd-PRA) in which the rods are affected first, followed by the cones. Unfortunately, most dogs affected by Cord1-PRA will eventually become blind. There is no known cure at this time.
The age of onset can vary with this disorder. Some dogs will first begin experiencing problems at around 6 months of age, though the average age of onset is around 5 years of age. A small percentage of dogs do not experience any symptoms until as late as 10 years of age. It is not yet known why some dogs will experience late-onset PRA. It is likely due to the presence of other genetic modifiers that have not been determined at this time.
Because cord1-PRA is a recessive disorder, a dog must have two copies of the mutation in order for the disease to manifest. This means that a dog can have one copy of the mutation and not experience any signs or symptoms of cord1-PRA. This dog would be known as a carrier. The carrier can then pass on either the normal gene or the mutated gene to any offspring. If two carriers are bred, there is a 25% per puppy that they will develop symptoms of cord1-PRA.
Possible Results
| Genotype | Description |
|---|---|
| NR | No Result- Please submit a new sample for this animal. |
| P/P | At Risk: Dog has two copies of the cord1-PRA mutation and is at risk of developing the disorder. The mutation will always be passed on to every offspring. |
| P/P2 | Dog has two copies of cord1-PRA alleles. |
| P2/P2 | At Risk: Dog has two copies of the cord1-PRA mutation and is at risk of developing the disorder. The mutation will always be passed on to every offspring. |
| n/P | Carrier: Dog carries one copy of the mutation associated with cord1-PRA. Dog will not be affected by cord1-PRA but may pass the mutation to offspring. |
| n/P2 | Carrier: Dog carries one copy of the mutation associated with cord1-PRA. Dog will not be affected by cord1-PRA but may pass the mutation to offspring. |
| n/n | Clear: Dog is negative for the mutation associated with cord1-PRA. |
Reference
Wiik AC, Thoresen SI, Wade C, Lindblad-Toh K, Lingaas F. A population study of a mutation allele associated with cone-rod dystrophy in the standard wire-haired dachshund. Anim Genet. 2009 Aug; 40(4):572-4. [PubMed: 19392817]
Wiik AC, Wade C, Biagi T, Ropstad EO, Bjerkås E, Lindblad-Toh K, Lingaas F. A deletion in nephronophthisis 4 (NPHP4) is associated with recessive cone-rod dystrophy in standard wire-haired dachshund. Genome Res. 2008 Sep; 18(9):1415-21. [PubMed: 18687878]