Breeds Affected: Schapendoes
Samples Accepted: Blood, Buccal Swabs
Disease Information: Generalized Progressive Retinal Atrophy (gPRA) in the Schapendoe is adult-onset, usually between 2-5 years of age. Affected animals first demonstrate problems seeing in dim light, and within 2 years this usually progresses to full blindness.
Inheritance Information: gPRA 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/gpra The dog is a carrier, and can pass the allele on to approximately 50% of any offspring. If bred to another N/gpra carrier, approximately 25% of the offspring will be normal, 50% will be carriers, and 25% will be affected.
gpra/gpra The dog is affected. If bred to a normal animal, 100% of the offspring will be carriers. If bred to a N/gpra carrier, 50% of the offspring will be carriers and 50% will be affected.
– Carriers may be bred to normal animals (N/gpra 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/gpra x N/gpra) is not recommended due to the possibility of 25% of the offspring being affected.
– Affected animals (gpra/gpra) should not be used for breeding.
Test Information: This mutation test identifies a single base insertion of exon 6 of the CCDC66 gene.
Dekomien, G., Vollrath, C., Petrasch-Parwez, E., Boevé, M.H., Akkad, D.A., Gerding, W.M., Epplen, J.T.: Progressive retinal atrophy in Schapendoes dogs: mutation of the newly identified CCDC66 gene. Neurogenetics 11:163-74, 2010. Pubmed reference: 19777273. DOI: 10.1007/s10048-009-0223-z.
Further information is available at the Online Mendelian Inheritance in Animals website.