Breeds Affected: Cardigan Welsh Corgi, Chinese Crested Dog, Pomeranian
Samples Accepted: Blood, Buccal Swabs
Disease Information: Rod-Cone Dystrophy 3, also known as rcd3, is a disease in which the cone and rod cells in the retina degenerate, leading to blindness. It is classified as early-onset.
Inheritance Information: Rcd3 is autosomal recessive, meaning that animals with two copies of this allele will be affected. Animals with one copy of the gene will be clinically-normal carriers.
The possible genotypes are:
N/N The dog is normal, and cannot produce affected offspring.
N/rcd3 The dog is a carrier, and can pass the allele on to approximately 50% of any offspring. If bred to another N/rcd3 carrier, approximately 25% of the offspring will be normal, 50% will be carriers, and 25% will be affected.
rcd3/rcd3 The dog is affected. If bred to a normal animal, 100% of the offspring will be carriers. If bred to an N/rcd3 carrier, 50% of the offspring will be carriers and 50% will be affected.
– Carriers may be bred to normal animals (N/rcd3 x N/N) without any risk of producing affected offspring. The offspring should be tested before breeding to determine if they are carriers or normal.
– Breeding two carriers (N/rcd3 x N/rcd3) is not recommended due to the possibility of 25% of the offspring being affected.
– Affected animals (rcd3/rcd3) should not be used for breeding.
Test Information: This mutation test identifies a single base deletion in the PDE6A gene.
Donner, J., Kaukonen, M., Anderson, H., Möller, F., Kyöstilä, K., Sankari, S., Hytönen, M., Giger, U., Lohi, H. :Genetic Panel Screening of Nearly 100 Mutations Reveals New Insights into the Breed Distribution of Risk Variants for Canine Hereditary Disorders. PLoS One 11:e0161005, 2016. Pubmed reference: 27525650. DOI: 10.1371/journal.pone.0161005.
Downs, L.M., Hitti, R., Pregnolato, S. and Mellersh, C.S. Genetic screening for PRA‐associated mutations in multiple dog breeds shows that PRA is heterogeneous within and between breeds. Veterinary ophthalmology, 17(2):126-130, 2014. Pubmed reference: 24255994. DOI: 10.1111/vop.12122.
Petersen-Jones, S.M., Entz, D.D., Sargan, D.R.: CGMP phosphodiesterase-alpha mutation causes progressive retinal atrophy in the Cardigan Welsh corgi dog Investigative Ophthalmology & Visual Science 40:1637-1644, 1999. Pubmed reference: 10393029.
Further information is available at the Online Mendelian Inheritance in Animals website.