After a prolonged research study of dogs’ eye health, anatomy and glaucoma in dogs with Swedish Vallhund breed, scientists have recently detected a defect in a gene called MERTK. This deformity is responsible for a form of progressive retinal atrophy (PRA), a genetic disease that causes blindness and glaucoma in dogs.
A collaboration on this research project between scientists from Finland and the US, more specifically University of Helsinki (led by Dr. Saija Ahonen and Professor Hannes Lohi) and Michigan State University (led by Dr. András Komáromy), have produced results that can prove to be the answer to cure diseases that cause blindness not only in dogs but humans as well. Study findings have been published on PLoS ONE journal, in a paper A Novel Canine Retinopathy Associated with MERTK .
Until very recently, the disease of dogs’ retina that can be inherited as autosomal recessive trait by nearly all dog breeds was the most common cause for blindness in dogs and even people, and it still cannot be cured. It is very similar to retinitis pigmentosa disease, which is only found in humans, and has been classified as progressive retinal atrophy (PRA); it causes bilateral degeneration of dog’s eye retina, and the dog usually becomes blind after an ongoing battle with progressive vision loss.
Because the fundamental structure of dogs’ eyes is very similar to that of human eyes, discovery of the defect in MERTK gene will also contribute to a better understanding of how blindness is caused in humans, and provide means for new therapies and potential cure of the disease in humans, and possibly glaucoma in dogs.
“The work to characterize these diseases in two Nordic dog breeds drew from well-established international collaborations between clinicians, geneticists, and dog breeders. This type of longstanding, multi-disciplinary collaboration certainly strengthens a team’s response to the challenges of unraveling complex problems and creating innovative solutions,” says Professor Hannes Lohi.
New study’s impact on cure of blindness and glaucoma in dogs
The research project was already ten years in the making, with scientists having started their research of a newly emerging PRA disease in dogs back in the late 1990s. By now, the team of scientists from Sweden, Finland and the US have traveled across three continents, examining dogs with this disease and anything related, and have tested 324 dogs in seven different countries.
“I drove from Philadelphia to Michigan to examine the affected dogs, and began visiting dog shows and other venues around North America and Scandinavia to examine other Swedish Vallhund dogs. It is wonderful to see that these trips helped us to later get this far to understand these conditions,” said Dr. András Komáromy.
Today, the researchers are focusing on regulatory mutations in dogs and examining the whole system of the disease, which is closely related to overexpression of the mutated gene in dogs. Scientists say they will also be looking into finally developing gene therapy methods with the use of MERTK inhibitors, while also revising local breeding programs to reduce the frequency of how often the PRA disease appears in Swedish dog breeds.
Similarly to the case of mutant genes in Newfoundland dogs, there’s a possibility to substantially decrease the number of dogs that inherit the progressive retinal atrophy disease, and possibly even eradicate it completely through thorough supervision of dog breeding practices. Let’s keep the fingers crossed.
- Ann E. Cooper, Saija Ahonen, Jessica S. Rowlan, Alison Duncan, Eija H. Seppälä, Päivi Vanhapelto, Hannes Lohi, András M. Komáromy. A Novel Form of Progressive Retinal Atrophy in Swedish Vallhund Dogs. PLoS ONE, 2014; 9 (9): e106610. doi: 10.1371/journal.pone.0106610