Breeds Affected: Labrador Retriever
Samples Accepted: Blood, Buccal Swabs
Disease Information: Skeletal dysplasia (SD2) is a form of dwarfism in the Labrador Retriever in which the body size is normal but the legs are approximately 6 cm shorter than normal. The front legs may be more affected than the hind legs. Due normal variation in the Labrador breed, it may be difficult to distinguish dogs with SD2 from normally shorter dogs.
Inheritance Information: Skeletal dysplasia 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/sd2 The dog is a carrier, and can pass the allele on to approximately 50% of any offspring. If bred to another N/sd2 carrier, approximately 25% of the offspring will be normal, 50% will be carriers, and 25% will be affected.
sd2/sd2 The dog is affected, and if bred to a normal animal, 100% of the offspring will be carriers. If bred to an N/sd2 carrier, 50% of the offspring will be carriers and 50% will be affected.
– Carriers may be bred to normal animals (N/sd2 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/sd2 x N/sd2) is not recommended due to the possibility of 25% of the offspring being affected.
– Affected animals (sd2/sd2) should not be used for breeding to avoid propagating the dwarfism phenotype.
Test Information: This test identifies a single base change in the gene COL11A2.
Frischknecht, M., Niehof-Oellers, H., Jagannathan, V., Owczarek-Lipska, M., Drögemüller, C., Dietschi, E., Dolf, G., Tellhelm, B., Lang, J., Tiira, K., Lohi, H., Leeb, T.: A COL11A2 mutation in Labrador retrievers with mild disproportionate dwarfism. PLoS One 8:e60149, 2013. Pubmed reference: 23527306. DOI: 10.1371/journal.pone.0060149
Further information is available at the Online Mendelian Inheritance in Animals website.