Rod Cone Dysplasia Type 3 rcd3-PRA Test Code 313
For breeds: Cardigan Welsh Corgi, Chinese Crested & Pomeranian
Progressive Retinal Atrophy (PRA), a group of inherited blinding canine diseases, is seen in many pure breeds, although the exact genetic cause is known for only a few. A specific form of PRA, Rod Cone Dysplasia Type 3 in Corgis and some other breeds, is of early onset with signs of retinal abnormality and vision loss already by one year of age. The Corgi form of PRA is called rcd3, that is, the third PRA form with rod-cone degeneration. Rod and cone refer to the shapes of cells in the retina that respond to light, but are progressively degenerating when affected with this disease. Corgi PRA is caused by a mutation in the gene called PDE6A whose normal state is essential for normal vision. Within a set of nearly 600 dogs, a carrier rate of about 8.5% was reported.
Although PRA can't be treated, it can be prevented. The key to preventing autosomal recessive diseases lies in identifying dogs that do not carry the defective genes. The mutation based rcd3-PRA test unequivocally and reliably identifies normal dogs. Called genetically clear/normal, such dogs can pass only the normal gene on to all their pups. This means that none of their pups can ever be affected with this form of PRA. These clear dogs can be bred to any mate, even to PRA-affected dogs that may be desirable breeding prospects for other reasons.
The test also identifies carriers and affected dogs with 100% accuracy. But while a normal dog may be bred to any other dog, carriers and affecteds must be bred only to normal dogs. Desirable breedings include at least one parent proven "normal" by the DNA-based rcd3-PRA test, as shown in the shaded areas of the following table. Breeding untested dogs or breeding two carrier dogs puts you at risk of producing PRA-affected pups.
For more information on this breed and the disease, go to: Cardigan Welsh Corgi Website
1. Petersen-Jones SM, Entz DD, Sargan DR. cGMP phosphodiesterase-alpha
mutation causes progressive retinal atrophy in the Cardigan Welsh corgi
dog. Invest Ophthalmol Vis Sci. 1999 Jul; 40(8):1637-44.
2. Petersen-Jones SM, Zhu FX. Development and use of a polymerase chain reaction-based diagnostic test for the causal mutation of progressive retinal atrophy in Cardigan Welsh Corgis. 2000. American Journal of Veterinary Research 617):844-846.
Page last updated February 20, 2017
Copyright 2005 OptiGen · Design and Programming by Spider Graphics Corporation®