Genes Affected: PRCD
Inheritance: Autosomal recessive
Mutation: CanFam3.1 g.4188663C>T c.5 G>A, exon1
OMIA link: 001298-9615

Appropriate breeds for testing:
American Eskimo Dog, American Hairless Terrier, Australian Cattle Dog, Australian Cobberdog, Australian Koolie,  Australian Shepherd, Australian Stumpy Tail Cattle Dog, Barbet,, Biewer, Bolonka Zwetna, Boykin Spaniel, Carolina Dog, Chesapeake Bay Retriever, Chihuahua, Chinese Crested, Cocker Spaniel, English Cocker Spaniel, English Shepherd, Entlebucher Mountain Dog, Finnish Lapphund, Giant Schnauzer, Golden Retriever, Karelian Bear Dog, Koolie, Kuvasz, Labrador Retriever, Lagotto Romagnolo, Lapponian Herder, Miniature American Shepherd, Miniature Australian Cattle Dog, Miniature Australian Shepherd, Miniature Poodle,  Norwegian Elkhound, Nova Scotia Duck Tolling Retriever, Poodle, Portuguese Podengo Pequeno, Portuguese Water Dog, Rat Terrier, Russian Tsvetnaya Bolonka, Schipperke,  Silky Terrier, Spanish Water Dog, Standard Poodle, Swedish Lapphund, Toy Australian Shepherd, Yorkshire Terrier

Symptoms:  
The symptoms of the disease are degeneration of the rods and cones in the eye (Spencer et al., 2016). Dogs are born with normal vision, but in adolescence or early adulthood, they start showing clinical signs (Miyadera, 2014). The disease generally initially manifests as a lack of coordination in dim light and night blindness (Miyadera, 2014). Affected dogs may also show an aversion to bright lights, difficulty navigating familiar areas, and an inability to focus on small objects such as balls or toys (Miyadera, 2014). As the cones of the eye degenerate, night blindness progresses to daytime blindness (Miyadera, 2012). Ultimately, the disease leads to total blindness (Miyadera, 2012). Currently, there is no cure or known treatment to slow the progression of PRCD. Progression varies from one individual to another, but most dogs become completely blind within 1 to 2 years (Zangerl et al., 2006) (Free translation from the OMIA website).

References:  
- Spencer, W.J., Pearring, J.N., Salinas, R.Y., Loiselle, D.R., Skiba, N.P., Arshavsky, V.Y. (2016). Progressive rod-cone degeneration (PRCD) protein requires N-terminal S-acylation and rhodopsin binding for photoreceptor outer segment localization and maintaining intracellular stability. Biochemistry 55:5028-5037. PubMed reference: 27509380. DOI: 10.1021/acs.biochem.6b00489.  
- Miyadera, K. (2014). Inherited retinal diseases in dogs: advances in gene/mutation discovery. Dobutsu Iden Ikushu Kenkyu 42:79-89. PubMed reference: 26120276. DOI: 10.5924/abgri.42.79.  
- Miyadera, K., Acland, G.M., Aguirre, G.D. (2012). Genetic and phenotypic variations of inherited retinal diseases in dogs: the power of within- and across-breed studies. Mamm Genome 23:40-61. PubMed reference: 22065099. DOI: 10.1007/s00335-011-9361-3.  
- Zangerl, B., Goldstein, O., Philp, A.R., Lindauer, S.J., Pearce-Kelling, S.E., Mullins, R.F., Graphodatsky, A.S., Ripoll, D., Felix, J.S., Stone, E.M., Acland, G.M., Aguirre, G.D. (2006). Identical mutation in a novel retinal gene causes progressive rod-cone degeneration in dogs and retinitis pigmentosa in humans. Genomics 88:551-563. PubMed reference: 16938425. DOI: 10.1016/j.ygeno.2006.07.007.