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CODE: C116
Please be advised that HealthGene laboratory does
not accept samples from US residents for this test.
INTRODUCTION:
DESCRIPTION
The Briard dog is affected with an inherited retinal disorder characterized by congenital night blindness with
various degrees of visual impairment under photopic illumination. Vision in affected dogs ranges from normal day
vision to profound day blindness. The disease was initially described in Swedish (Briard) dogs as a stationary
disorder analogous to human congenital night blindness. Congenital Stationary Night Blindness (CSNB) in Briard
breed is caused by a mutation in the gene RPE65. RPE65 encodes a 65-kDA protein expressed exclusively in retinal
pigment epithelium and is involved in the biochemistry of vision.
INHERITANCE
Since the disease shows an autosomal recessive mode of inheritance, two copies of the defective gene, one inherited
from each parent, have to be present for a dog to be affected by the disease. Dogs with one copy of the defective
gene and one copy of the normal gene - called carriers - show no symptoms but can pass the defective gene onto their
offspring.
DNA TEST
A DNA-based test is now available for the detection of Congenital Stationary Night Blindness in Briards. This test
utilizes molecular probes that are 100% specific for the detection of the gene (RPE65) associated with CSNB. Using
the PCR, RPE65 is detected, amplified, and the results are interpreted to determine whether the mutation for CSNB is
present in two copies (homozygous recessive), or whether the dog is a carrier of the mutation (heterozygous). Dogs
that are diagnosed as having two copies of the mutation show clinical symptoms of the disease in as early as 5-6 weeks
of age. Dogs that are diagnosed as carriers show no signs of the disease but are still able to produce affected pups.
It is important to eliminate such carriers from a breeding population since they represent a hidden reservoir of the
disease that can produce affected dogs at any time, depending on the genetic standing of their mate. This test provides
definitive information on the genetic status of this disease, giving breeders the information to eradicate the disease
from their lines.
BREEDS:
Briard
TEST RESULTS:
| Result |
Interpretation |
| Normal |
Homozygous for normal gene, will never develop the disease |
| Carrier |
Carries one mutant gene, but will never develop the disease |
| Affected |
Homozygous for disease gene and will develop the disease |
SAMPLES:
Two types of samples can be submitted for this DNA test:
- A blood sample in a lavender (EDTA) tube;
- Cheek swabs - Order a Sample Collection Kit!
PRICE:
-$85.00*
Special contract prices are available for Breeder Clubs. Please contact us for more information.
* - subject to the applicable taxes (5% GST Canadian Residents only)
CERTIFICATION OF RESULTS:
HealthGene will provide a certificate for each test result.
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