Breeds Affected: Brittany
Samples Accepted: Blood, Buccal Swabs
Disease Information: A deficiency in Complement 3 (C3) results in the body having a greatly reduced immune response, leaving the affected animals susceptible to frequent bacterial infections. Kidney disease (membranoproliferative glomerulonephritis) is also common.
Inheritance Information: C3 Deficiency 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/c3d The dog is a carrier, and can pass the allele on to approximately 50% of any offspring. If bred to another N/C3d carrier, approximately 25% of the offspring will be normal, 50% will be carriers, and 25% will be affected.
c3d/c3d The dog is affected. If bred to a normal animal, 100% of the offspring will be carriers. If bred to an N/c3d carrier, 50% of the offspring will be carriers and 50% will be affected.
– Carriers may be bred to normal animals (N/c3d 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/c3d x N/c3d) is not recommended due to the possibility of 25% of the offspring being affected.
– Affected animals (c3d/c3d) should not be used for breeding.
Test Information: This mutation test identifies a single base pair deletion in the C3 gene.
Ameratunga, R., Winkelstein, J.A., Brody, L., Binns, M., Cork, L.C., Colombani, P., Valle, D. : Molecular analysis of the third component of canine complement (C3) and identification of the mutation responsible for hereditary canine C3 deficiency. J Immunol 160:2824-30, 1998. Pubmed reference: 9510185.
Further information is available at the Online Mendelian Inheritance in Animals website.