The GPRA-project November 2014
Status from the GPRA-project, November 2014.
GPRA is a hereditary disease, which is the same as the disease Retinitis pigmentosa (RP) on humans. The first symptoms are poor night vision and narrowing of the visual field to "tunnel vision" and will end in blindness. The disease is highly variable in both humans (RP) and in dogs, which means that many different genes and mutations that cause variations of the disease are recognized. In humans it is found mutations in about 50 different genes, but there are still many of the mutations which have not been found.
There are also many genes in dogs. It is about 20 different genes with mutations causing PRA. These mutations explain PRA cases in approximately 50 breeds in total. When the research in PRA started in dogs in general, it was to believe that all PRA cases within the same breed caused by the same mutation. The situation was unfortunately often more complicated than that; it now turns out that there, for many breeds, are hereditary PRA cases, which not can be explained by the mutation we have recognized.
The first phase of the official PRA project in Shelties now approaching to an end and it is time to take a summary. Many enthusiastic sheltie owners have through several years contributed to the collection of important specimens, both of PRA sick dogs, dogs with eye disease retinopathy, and blood samples from a variety of healthy dogs that are important as so-called controls. The research has recognized a mutation in one gene which course/ associates with PRA in many of the affected shelties, and many dogs are carriers of the disease.
The challenge in sheltie are that there probably are more than only this one mutation gene, which provides PRA, and in addition it seems that retinopathy is caused by another gene than what we have discovered. This is the same situation as we have seen in other breeds; there are more than one mutation who gives PRA, and for shelties we have retinopathy in addition.
The further road
Everyone who has participated with blood samples to the PRA project will be notified if their dog has the gene in double doses (homozygous), or is a carrier of the gene (only one copy). Those who have PRA dogs, which not have an explanation of the mutation discovered, will also have a notification.
Even if the official project (and funding) now comes to the end, we want to assist the club with the work ahead. It should be possible to find mutations that causes the - so far - "unexplained" PRA cases, as well as the mutation that causes retinopathy. To achieve these goals, it is important that sheltie-owners continue to submit blood samples when new PRA cases and suspected retinopathy cases are diagnosed.
Please be aware of that blood samples must be followed by a form which can be found at www.nssk.no
We now have the advantage that we can compare to the beginning of the project, and use the new PRA-test developed to characterize all new blood samples. It will provide a better diagnosis and will facilitate the work of unexplained PRA-cases and retinopathy.
In addition to regular eye tests, it may be important to use the ERG as well in cases not proven a clear PRA diagnosis. This will be an important and necessary tool to distinguish between PRA and retinopathy, and will be required to facilitate the further work to find the missing PRA-genes.
The project group is delighted to, in near future, to offer a test for the one mutation variant of PRA in shelties.
Unfortunately the research took much longer than we had hoped for in the beginning, but with this knowledge gained both on the importance of accurate diagnosis and the new genetic test, the work with the other issues probably will go faster if it can be collected more blood samples.
The project group want to thank you all for a good cooperation with the club, both with research money and blood samples, and will soon return with more information on the results of the current genetic testing.
To be informed about pedigrees with PRA-lines, please have a look at the PRA-site at www.nssk.no
The Norwegian Shetland Sheepdog Club's GPRA-Committee
Account number to the GPRA-project in Norway:
Address for bank transfer from abroad:
The PRA-Project, Norsk Shetland Sheepdog Club
Den Norske Bank, Farmannsgaten 2, N-1600 Fredrikstad, Norway
Account number: 5010.05.65517 - Swift-address: DNB ANO KK FRE
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