Breakthroughs for Golden Retriever Health: Finding Genes for Progressive Retinal Atrophy and Ichthyosis
By Ann F. Hubbs DVM, PhD
Progressive Retinal Atrophy – GR_PRA1
Big news from the 2010 Advances in Canine and Feline Genomics Conference in Baltimore, MD – researchers now believe that there are three different genetic conditions that can cause progressive retinal atrophy (PRA) in Golden Retrievers. PRA is a clinical disease characterized by retinal degeneration and blindness. In affected dogs, PRA can be diagnosed when fully developed by a veterinary ophthalmologist, but that is often in a mature dog that may have been bred many times. It can be diagnosed earlier using electroretinography. Since 2008, a genetic test for one form of PRA, prcd-PRA has been available (Hubbs, online; Optigen, 2010a). Prcd-PRA is a recessive genetic disease meaning that an affected Golden must have two abnormal copies of the prcd-PRA gene to get PRA. Both genetically affected dogs and unaffected carriers of this genetic condition can be identified by DNA testing at any age, including in young puppies.
At the genomics conference on September 24, Louise Downs of the Animal Health Trust in the United Kingdom, and her colleagues announced the identification of a new form of PRA that affects Golden Retrievers (Downs et al, 2010). This new form of PRA is also caused by a recessive mutation and caused 70 percent of the PRA cases in their study. Recently, the Animal Health Trust has made the resulting DNA test commercially available. In the supporting literature, they report that their research suggests that the mutation causing this new form of PRA, tentatively called GR_PRA1, is found in roughly 5 percent of the Goldens in the UK, but less than 0.5 percent of the Goldens from the US (Animal Health Trust). Louis Downs and colleagues also reported that still another genetic condition appears to cause some cases of PRA in Golden Retrievers but that gene has not yet been identified.
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