Involvement of PRCD and RPGR Genes in Progressive Retinal Atrophy in Locally Bred Canines

Abstract

Progressive Retinal Atrophy is a group of genetically inherited diseases in various canine breeds. The disease begins with retinal damage and progresses to blindness. Abnormalities in various genes are linked with different disease variants, and in most cases, involvement of one gene towards PRA is specific to one breed. However, Progressive Rod Cone Degeneration (PRCD) is an outlier. PRCD anomaly is associated with PRA in more than 20 breeds. The same gene mutation which causes PRA-prcd in dogs causes a form of Retinitis Pigmentosa in human. X-Linked Progressive Retinal Atrophy (XLPRA); a type of PRA, is a result of deletion in Retinitis Pigmentosa GTPase Regulator (RPGR). RPGR is a locus homologue of human Retinitis pigmentosa (RP3). We analyzed 22 clinically PRA positive dog samples for PRCD and RPGR association with PRA. We employed PCR-RFLP, capillary gel electrophoresis and sequencing. Experiment data suggests that tested mutation of PRCD has no association with PRA in all 15 Pomeranian and 1 Mongrel dogs which are locally bred by Indian breeders. In contrary, all English Cocker spaniel and Labrador Retriever samples showed PRCD association with PRA. Furthermore, accountability of tested mutations in RPGR has been concluded to be nil in all of the test samples.