Skeletal Dysplasia 2

Skeletal dysplasias are diseases that affect the bones and cartilage, among these is skeletal dysplasia type 2 which is typical of Labrador Retrievers.

Symptoms

Dogs with this dysplasia may be undersized and have dwarfism. In addition, the body is long in relation to the length of the legs, which are shorter than normal. The leg bones are shorter, thicker and slightly curved. The front legs are usually more affected than the hind legs. The height of their shoulders is reduced by approximately 6 cm compared to unaffected dogs.

Disease Management

The manifestations and treatment of skeletal dysplasias vary depending on the severity and type of the condition. Mild skeletal dysplasias may require little or no treatment as is the case with skeletal dysplasia 2.

Genetic basis

This disease follows an autosomal recessive mode of inheritance. Autosomal recessive inheritance means that the dog, regardless of sex, must receive two copies of the mutation or pathogenic variant to be at risk of developing the disease. Both parents of an affected dog must carry at least one copy of the mutation. Animals with only one copy of the mutation are not at increased risk of developing the disease, but may pass the mutation on to future generations. Breeding between dogs carrying genetic variants that can cause disease, even if they do not show symptoms, is not recommended.

Technical report

The variant that causes skeletal dysplasia 2 in Labrador Retriever dogs is c.143G>C. It is found in the COL11A2 gene which codes for one of the two alpha chains of type XI collagen, a type of collagen involved in skeletal development. This variant has incomplete penetrance and follows an autosomal recessive mode of inheritance, which means that dogs with two copies of the variant rarely have marked dwarfism and have a milder phenotype. Generally, no other health problems are observed.

Most affected breeds

Labrador Retriever

Bibliography

Frischknecht M, Niehof-Oellers H, Jagannathan V,et al. A COL11A2 mutation in Labrador retrievers with mild disproportionate dwarfism. PLoS One. 2013;8(3):e60149.