Progressive Retinal Atrophy in Irish Setters
Progressive retinal atrophy Irish Setters is an early-onset disorder leading to night-blindness and eventually total blindness. Symptoms can occur as early as 6 weeks of age. The gene responsible, the ß-subunit of rod cGMP phosphodiesterase, has now been identified and a DNA test devised. The disease shows an autosomal recessive mode of inheritance; therefore. two copies of the defective gene, one inherited from each parent, have to be present for a dog to be affected by the disease. Individuals 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. When two apparently healthy carriers are crossed, 25% (on average) of the offspring will be affected by the disease with a further 50% themselves being carriers.
The Animal Health Trust is now offering a DNA test for this disease distinguishing affected, carrier and normal individuals. The test probes directly the DNA of the ß-subunit of rod cGMP phosphodiesterase gene and provides definitive information on the genetic status of this disease, giving breeders the information to eradicate the disease from their lines.
The test can not only diagnose setters affected with this disease but can also detect those dogs which are carriers, showing no symptoms of the disease but 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.
DNA testing for pra in Irish setters is carried out under a screening scheme run with the Kennel Club. Results are made publicly available through the Kennel Club Website ( http://www.the-kennel-club.org.uk )
This test requires 2mls EDTA blood. Samples for testing should be sent, together with a completed DNA Testing form and payment of £65 inc VAT (cheque or credit card) for each sample to Genetic Services, Animal Health Trust, Lanwades Park, Kentford, Newmarket, Suffolk CB8 7UU.
DNA testing forms can be downloaded by clicking here.
Enquiries should be made to Symone Ingram telephone +44 (0) 8700 509144 or fax +44 (0) 8700 502461 or via e-mail to dnatesting@aht.org.uk.
