Breeds Affected: Papillon, Phalène
Samples Accepted: Blood, Buccal Swabs
Disease Information: Generalized Progressive Retinal Atrophy (PRA) in the Papillon and Phalène is adult-onset. As rod cells of the retina are lost, affected animals first demonstrate problems seeing in dim light. Although cone cells are also gradually lost, the progress is very slow, and affected dogs rarely go completely blind.
Inheritance Information: PRA 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/pra The dog is a carrier, and can pass the allele on to approximately 50% of any offspring. If bred to another N/pra carrier, approximately 25% of the offspring will be normal, 50% will be carriers, and 25% will be affected.
pra/pra The dog is affected. If bred to a normal animal, 100% of the offspring will be carriers. If bred to a N/pra carrier, 50% of the offspring will be carriers and 50% will be affected.
– Carriers may be bred to normal animals (N/pra 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/pra x N/pra) is not recommended due to the possibility of 25% of the offspring being affected.
– Affected animals (pra/pra) should not be used for breeding.
Test Information: This mutation test identifies an insertion/deletion mutation in the CNGB1 gene.
Ahonen, S.J., Arumilli, M., Lohi, H.: A CNGB1 Frameshift Mutation in Papillon and Phalène Dogs with Progressive Retinal Atrophy. PLoS One 8:e72122, 2013. Pubmed reference: 24015210. Doi: 10.1371/journal.pone.0072122.
Winkler, P.A., Ekenstedt, K.J., Occelli, L.M., Frattaroli, A.V., Bartoe, J.T., Venta, P.J., Petersen-Jones, S.M.: A Large Animal Model for CNGB1 Autosomal Recessive Retinitis Pigmentosa. PLoS One 8:e72229, 2013. Pubmed reference: 23977260. Doi: 10.1371/journal.pone.0072229.
Further information is available at the Online Mendelian Inheritance in Animals website.