Genetic Mutation Causing Blindness in Dogs, particularly in certain breeds, has long been a challenging issue for both pet owners and breeders. However, a recent breakthrough by scientists at the University of Cambridge offers new hope. By identifying the genetic mutation responsible for progressive retinal atrophy (PRA) in English Shepherd Dogs, researchers have not only pinpointed the cause of this incurable blindness but also developed a genetic test to eradicate the disease from future generations.
Table of Contents
Understanding Genetic Mutation Causing Blindness in Dogs.
Progressive Retinal Atrophy (PRA) is a concerning genetic condition affecting the vision of certain dog breeds, and more rarely, cats. Similar to retinitis pigmentosa in humans, PRA leads to the bilateral degeneration of the retina, resulting in progressive vision loss and eventual blindness.
PRA is a group of inherited diseases characterized by the deterioration of the retina, the light-sensitive layer of cells at the back of the eye. In nearly all affected breeds, PRA is passed down as an autosomal recessive trait. However, exceptions exist, such as the Siberian Husky, where it is inherited as an X chromosome-linked trait, and the Bullmastiff, which inherits it as an autosomal dominant trait.
PRA is generally characterized by an initial loss of rod photoreceptor cell function, followed by the deterioration of cone cells. This sequence results in night blindness as the first significant clinical sign for most dogs with PRA. The condition can be classified into two main types:
Dysplastic Disease: Where retinal cells develop abnormally from the start.
Degenerative Disease: Where retinal cells develop normally but degenerate over the dog’s lifetime.
Breeds Commonly Affected by PRA
Affected dogs are born with normal vision but typically lose their sight by the age of four or five. Until now, no treatment has been available to prevent this outcome.
The Genetic Discovery
The Research Process
The research at the University of Cambridge began when a search and rescue dog was diagnosed with PRA. The dog’s owner reached out to the university, prompting the team to collect DNA samples from both affected and unaffected English Shepherds. Using whole genome sequencing, they identified the mutation responsible for PRA.
The Specific Mutation
The mutation is recessive, meaning a dog must inherit two copies of the gene to develop PRA. Carriers of one copy do not suffer from the disease but can pass it on to their offspring, which has been a challenge due to the high level of inbreeding among dogs.
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Implications of the Discovery
This discovery marks the thirty-third genetic mutation causing an inherited disease in dogs identified by the Cambridge team, with 23 of these affecting vision. It underscores the impact of selective breeding on canine health and highlights the potential benefits of genetic testing.
The Cambridge team has developed a DNA test to detect the PRA mutation. Breeders can now identify carriers before any symptoms appear, allowing them to make informed breeding decisions and prevent the faulty gene from being passed to puppies.
Eradicating the Genetic Mutation
Gene Therapy and Other Treatments
While no treatment currently exists for PRA, the ability to detect the mutation allows for preventative measures that can ultimately eradicate the disease from future generations of English Shepherds.
Preventative Measures in Breeding
Breeders can purchase a commercial genetic testing service for £48 ($62), enabling them to screen their dogs before breeding. This affordable test offers a simple way to prevent PRA and ensure healthier offspring.
Broader Impact and Future Research
Insights for Human Genetic Diseases
PRA in dogs bears similarities to retinitis pigmentosa in humans, a condition that causes blindness. The Cambridge team believes their work could offer insights into the human version of the disease and potentially identify targets for gene therapy.
Next Steps in Research
The researchers are optimistic about their discovery’s implications for both canine and human health. Ongoing studies aim to explore further genetic conditions and improve breeding practices.
Conclusion
The University of Cambridge’s identification of the genetic mutation responsible for PRA in English Shepherd Dogs is a monumental step forward in veterinary medicine. By enabling breeders to screen for the mutation, this discovery offers a practical solution to prevent PRA and preserve the well-being of future generations. With this advancement, there is new hope for eliminating hereditary blindness in dogs and shedding light on similar conditions in humans.
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