Cloning and characterization of canine SHARP1 and its evaluation as a positional candidate for canine early retinal degeneration (erd).

Canine early retinal degeneration (erd) is an early onset form of canine progressive retinal atrophy phenotypically similar to human retinitis pigmentosa. In a previous study, the locus responsible for erd was mapped to canine chromosome 27 in the region corresponding to HSA12p, a region where no human retinal degeneration loci have been mapped. Canine SHARP1 gene has been localized on CFA27 in the erd interval by RH mapping, and considered as a positional candidate gene for erd. SHARP1 was cloned and sequenced from normal and erd affected dogs, and no disease-causing mutations were identified. Genotyping of 117 dogs from informative pedigrees did not reveal any recombinants between SHARP1 and erd. To date SHARP1 gene is the closest gene-specific marker to erd; genotyping additional informative pedigrees, and sequencing SHARP1 upstream regions from normal and affected dogs will be necessary to establish if SHARP1 is involved in this canine retinal disease.