DOG BLINDNESS HAS GENETIC LINK WITH HUMAN FORM
WASHINGTON (Reuters) -
The most common form of inherited blindness in dogs probably has genetic similarities with
a type of blindness found in humans, Cornell University reported Tuesday.
The genetic defect that makes the dogs blind seems to be the canine equivalent of the
human gene defect that causes RP17, one of many forms of the blindness known as retinitis
pigmentosa, it said in a statement.
The discovery, by researchers at Cornell and at the Fred Hutchison Cancer Research Center
in Seattle, may lead to genetic treatment for both the dogs and the humans, it added.
The dog disease, known as progressive rod-cone degeneration (pcrd), causes blindness in at
least five breeds of dog -- Labradors, poodles, English and American cocker spaniels and
Portuguese water dogs. Two to 3 percent of Labradors develop the disease and go blind in
adulthood.
Thousands of puppies could be saved from going blind. ''The identification of the pcrd
gene may lead not only to an unequivocal diagnostic test for dogs but also to gene therapy
for pcrd in dogs -- which eventually may be applicable to RP17 patients,'' said Gregory
Acland, a veterinary ophthalmologist at Cornell.
Geneticists would do this by cloning the normal gene, inserting a copy into a transfer
vector such as a harmless virus and injecting the gene-carrying vector into the back of
the eye. This might prevent or reverse the disease, it said.
Acland said he thought pcrd might be widespread among many other breeds of dog. The defect
would then be a mutation dating back to the time before the breeds diverged.
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