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Description
Progressive Retinal
Atrophy, more commonly known as PRA, is a general term for a group
of diseases causing degeneration of the retina, leading to a loss
of vision. One form of this disorder is known as cord1-PRA, which
stands for cone-rod dystrophy-PRA. Cord1-PRA is a genetic disorder
associated with a recessive mutation in the RPGRIP1 gene, which
codes for an important photoreceptor protein 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 photoreceptors responsible for detecting
bright light or daylight. Rods, or low-light photoreceptors, begin
degenerating secondarily. 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, and there is no cure at this time.
The age of onset can vary with this disorder,
some dogs will first begin experiencing problems around 6 months
in 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, however, it is likely due to the presence
of other genetic modifiers that have not been determined at this
time.
Because this disorder is recessive, a dog must
have two copies of the mutated gene to exhibit symptoms associated
with PRA. A dog can be a carrier of cord1-PRA, meaning it only has
one copy of the mutation, and not show any outward signs of retinal
degeneration. A carrier can still pass on the mutated gene to any
offspring; mating two carrier dogs can produce offspring affected
by cord1-PRA.
cord1-PRA Testing
Animal Genetics offers DNA testing and detection
of the gene mutation associated with cord1-PRA. Animal Genetics
only tests for this mutation in the breeds known to be affected
by cord1-PRA, including:
Miniature Long-Haired Dachshund
Miniature Wire-Haired Dachshund
Minature Smooth-Haired Dachshund
English Springer Spaniel
Cost
$45.00
US per sample.
Sample Collection
Collect sample using buccal swabs provided by
Animal Genetics. Ensure that the dog has not eaten within a few
hours of sample collection. Any food particles can inhibit the test.
Rub each of the swabs along the inside of the dog's mouth for 10-15
seconds, and allow the swabs to dry thoroughly. Label the provided
envelope with the dog's name, and place the swab inside it. Download
and complete a submission form for each sample and send along with
payment to Animal Genetics for testing.
Results
Results are given using the following symbolic
notation:
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PRA/PRA
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AFFECTED:
The dog carries two copies of the mutant gene and is homozygous
for the cord1-PRA mutation. The dog will display symptoms associated
with the disorder, and will always pass on a copy of the mutation
to any offspring. |
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n/PRA
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CARRIER:
Both the normal and mutant copies of the gene detected. The
dog is a carrier for cord1-PRA, and could pass on either allele
to any offspring. |
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n/n
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CLEAR:
Tested negative for the cord1-PRA mutation. |
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