Mutation in the RPE65 gene causing hereditary retinal dystrophy in the Briard dogs: application of a new detection method

Inherited eye diseases are widespread in most of the pure dog breeds and they show a severe impact on canine health, welfare and working ability. Congenital stationary night blindness (CSNB) was originally described in Briards. CSNB is slow progressive retinal degeneration with very early onset of clinical symptoms and is inherited in an autosomal recessive manner. The causative mutation (Y16567.1: c.487_490delAAGA) for CSNB was identified in exon 5 of the RPE65 gene. This deletion results in a frameshift and leads to a premature stop codon and expression of a non-functional protein. To date, only expensive, laborious or unpractical methods have been used for detection of the mutation in the canine RPE65 gene. The main goals of this study were to develop a new method for routine genotyping of the causative mutation and to assess its occurrence in the Czech population of Briards. The method of electrophoresis in the gel Spraedex EL600 can be widely used for genotyping of the RPE65 gene as a basis of proper genetic counselling and an improvement of genetic health in the Briard populations. In the studied population, the following frequencies of alleles + (wild) and - (mutant) were observed - 0.939 and 0.061, respectively.