Real-Time Detection of the Mutation Responsible for Progressive Rod-Cone Degeneration in Labrador Retriever Dogs Using Locked Nucleic Acid TaqMan Probes

Abstract

Progressive rod-cone degeneration (prcd) is a late onset, autosomal recessive, inherited disease in dogs caused by a G > A substitution in the PRCD locus. prcd has been reported in more than 18 breeds, including Labrador Retriever dogs. In this study, a real-time polymerase chain reaction (PCR) assay, exploiting the features of locked nucleic acid (LNA) fluorescent-labeled probes, was developed to genotype the sequence variants responsible for the disease. Two Labrador Retrievers were diagnosed with prcd by ophthalmological examination performed by a panelist of the Italian hereditary eye disease control program. The 2 dogs, as well as 8 related and 14 unrelated Labrador Retrievers, were genotyped with both direct sequencing of the disease locus and real-time LNA TaqMan PCR assay. Even though the region surrounding the mutation was predicted to be highly structured, making probe annealing difficult, the real-time PCR assay allowed researchers to correctly genotype the dogs in all cases with a sensitivity threshold of 4 ng/reaction of genomic DNA. A real-time PCR assay will allow a high-throughput analysis of a larger cohort of dogs, thereby enabling researchers to investigate the prevalence of the mutated allele in the affected breeds.