PRA

There appears to be three types of PRA in Golden Retrievers, prcd-PRA, PRA1, and an unidentified third type.

prcd-PRA
The genetic disorder, prcd-PRA , causes cells in the retina at the back of the eye to degenerate and die, even though the cells seem to develop normally early in life. The “rod” cells operate in low light levels and are the first to lose normal function. Night blindness results. Then the “cone” cells gradually lose their normal function in full light situations. Most affected dogs will eventually be blind. Typically, the clinical disease is recognized first in early adolescence or early adulthood. Since age at onset of disease varies among breeds, you should read specific information for your dog. Diagnosis of retinal disease can be difficult. Conditions that seem to be prcd-PRA might instead be another disease and might not be inherited. OptiGen’s genetic test assists in making the diagnosis. It’s important to remember that not all retinal disease is PRA and not all PRA is the prcd form of PRA. Annual eye exams by a veterinary ophthalmologist will build a history of eye health that will help to diagnose disease.

Unfortunately, at this time there is no treatment or cure for PRA. If your dog is affected, you may find it helpful to read about other owners’ experiences living with blind dogs. (suggested links:www.eyevet.org and www.blinddogs.com)

PRA1
A research team at the Animal Health Trust in the UK and the Swedish University in Upsaala have recently identified a mutation, GR_PRA1, that causes Progressive Retinal Atrophy (PRA) in the golden retriever. OptiGen had previously identified another form of PRA caused by the prcd mutation in this breed. With the aid of the new GR_PRA1 DNA test, the cause of the majority of PRA cases in the golden retriever can now be explained. Unfortunately, there are still a few cases of PRA in the golden retriever that are not caused by either of the known mutations. These cases will continue to be a subject of ongoing PRA research. If you know of any PRA-affected golden retrievers, please encourage the owners to contact OptiGen to learn about our Free PRA Testing/Research program : (http://www.optigen.com/opt9_research.html)

Current statistics on the incidence of GR_PRA1 indicate that the disease is primarily of concern in European lines of golden retriever however we have confirmed that GR_PRA1 is the cause of some of the PRA-affected in golden retrievers that have been sent to OptiGen for research from Canada and the USA. OptiGen will be happy to provide the Golden Retriever Club health committees with regular updates of the statistics on the incidence of PRA, both prcd and GR_PRA1, as more dogs are tested.

Similar but completely unrelated to prcd, GR_PRA1 is inherited in an autosomal recessive manner. This means that GR_PRA1 disease will occur only if two copies of the mutation are present; carriers of one copy of the mutation do not show disease. By ensuring that at least one parent is Normal/Clear of GR_PRA1 then no GR_PRA1 affected offspring will be produced in a mating.  See the chart below for expected breeding outcomes when the GR_PRA1 status (Genotype) has been determined by DNA testing.

The above information is from Optigen. Click for infromation on testing for prcd-PRA &PRA1.

**To date (2011) we have tested 5 dogs for PRA via DNA testing, 5 for prcd-PRA and 4 for PRA1. Of these dogs tested we have 4 dogs tested Clear and 1 tested as a Carrier for the prcd-PRA Mutation, 4 have tested Clear for PRA1.

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