 |
 |
 |
Progressive retinal atrophy (PRA) is the name given to a group of hereditary retinal diseases in dogs. Although there are several classifications of the disease according to the age of onset of the disease and the types of retinal pathology which occur, almost all forms of PRA eventually lead to complete blindness.
The first sign of most types of PRA is night blindness. This is because the rods (the cells which allow vision in reduced light) degenerate earlier than the cones (the cells which allow vision in the bright light). Often dogs will bump into objects in a dimly lighted room; a room in which a person can see well enough to avoid the object. Gradually dogs with PRA will lose their ability to see in lighted rooms and will go completely blind. They will frequently have dilated pupils. Sometimes owners will notice increased shininess or hyperreflectivity to the back of the eye.
In the initial stage of the PRA, however, a dog would have a completely normal behaviour, especially in its familiar surroundings. In places that are unfamiliar and strange to him, his increasing uneasiness is often interpreted as a behavioural disturbance.
In all breeds except Siberian Huskies, Samojede (sex linked recessive trait) and Mastiffs (autosomal dominant trait), PRA is inherited as an autosomal recessive trait.
Autosomal recessive inheritance means that an affected animal must have inherited 2 defect copies of the PRA causing gene, 1 from each parent. Dogs with normal copies of this gene or with only 1 defect copy (carrier) will be clinically normal but the carrier will pass the affected copy to approximately half the offspring. As long as carriers are mated to normal animals, the offspring will be unaffected but some will remain carriers. If 2 carriers are mated, some of the offspring (approximately 25%) will be affected.For dog breeders a genetic test will be the only way to identify carriers of the gene for PRA. When there are no genetic tests available, an early diagnosis is not possible. Worldwide, only for few breeds a direct genetic test (Irish Setter, Cardigan Welsh Corgi, Sloughi, Siberian Husky, Samojede, Miniature & Toy Poodle, Engl. & Am. Cocker Spaniel, Labrador Retriever, Portuguese Waterdog, American Eskimo Dogs, Australian Cattle Dog, Australian Stumpy Tail Cattle Dogs, Entlebucher Mountain Dog, Nova Scotia Duck Tolling Retriever and Chesapeak Bay Retriever) could be developed.
Since many years, reseach has been going on in the molecular genetics filed in oder to find the PRA producing gene mutations and to develop genetic tests for the various breeds. At the Institute of Human Genetics at the Ruhr University in Bochum, Germany, under the direction of Prof. Dr. Epplen we are doing research work on the PRA mutation genes. This PRA research project is being financed by the Society for Kynological Research (GFK).
In July 2000 our team succeeded in discovering a new PRA-producing mutation of the Sloughis breed.
In the meantime, the Institute of Human Genetics in Bochum developed a direct gene test for this breed. Blood samples of the affected animals, as well as the blood of the parents, the litter and other afflicted animals were of great importance to the Institute. This success was greatly due to the commitment and concern of the breeders and the dog owners having sick animals.
We need DNA blood samples (5-10 ml blood in EDTA test tubes) of PRA affected dogs, as well as the blood of the parents, the grandparents and the litter.
The test tubes with the name of the dog, a copy of the genealogical tree and the tests results of the eye examination must be mailed (unchilled) to the address mentioned below, possibly at the beginning of a week.
Dr. Gabriele Dekomien
Humangenetik
Gebäude MA 5
Ruhr-Universität
Universitätsstr. 150
44801 Bochum
GermanyTel.: +49 234/32-25764
Fax: +49 234/32-14196
E-Mail: gabriele.dekomien@ruhr-uni-bochum.de
Optigen
Instructions form shipping blood sample
