Scientists have used dogs with a particular form of genetic blindness to discover a clue as to how the disease works. The Norwegian and US researchers reported their findings in the journal Genome Research last week.
Cone-rod dystrophies (CRDs) are relatively rare forms of blindness in humans characterised by progressive loss of the cones in the retina, the cells that enable vision in bright light. The disease can initially cause 'day-blindness' in which only vision in bright light is affected, but this can lead to full loss of vision.
Inherited vision disorders are common in dogs, but the canine form of CRD is limited to a few breeds, one of which is the wire-haired dachshund. The study was led by Dr Frode Lingaas at the Norwegian School of Veterinary Science and used genome-wide analyses to look at 13 dogs with the disorder and 13 without. They found a mutation in the form of a deletion on chromosome 5 in the nephronophthisis 4 (NPHP4) gene in the diseased dogs, the gene product of which is therefore likely to be responsible for the disorder.
Interestingly, the same gene has also been linked to eye and kidney disorders in humans in the past. Since this mutation only affects the eyes, Lingaas explains, it suggests that 'this gene might be a candidate for human patients with eye disease only'.
The scientists hope that the findings can be used for discovering more about the disease in dogs, and using techniques to replace the gene product with a functional protein to restore vision in the dachshunds.
They hope that this could then potentially be used for gene therapy techniques in humans. Professor David Hunt, from the Institute of Ophthalmology, UK, said that the finding could help scientists understand CRDs in humans, but that 'it is a wide spectrum of conditions, not just one. The problem is that there is a wide range of underlying defects and we haven't got a magic bullet which can target these all at once'.
Sources and References
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Dachshunds gene 'blindness clue'
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Mutation Found In Dachshund Gene May Help Develop Therapies For Humans With Blindness
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Gene Behind Rare Eye Disease in Dachshunds Discovered
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Dachshunds help scientists to fight 'day blindness'
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