Oculoskeletal Dysplasia 2 (OSD2)

 

Gene: COL9A2

Transmission: Autosomal recessive for dwarfism; autosomal dominant with variable penetration for eye problems.

For an autosomal recessive genetic disease an animal must have two copies of the mutation in question to be at risk of developing the disease.  Both parents of an affected animal must be carriers of at least one copy of the mutation.  Animals that have only one copy of the mutation are not at risk of developing the disease but are carrier animals that can pass the mutation on to future generations.

For an autosomal dominant genetic disease, an animal must have at least one copy of the mutation in question to be at risk of developing the disease.  Animals with two copies of the mutation generally have more severe symptoms and an earlier onset of the disease than animals with just one copy of the mutation.  One or both of the parents of an animal with the mutation has one or two copies of the mutation.  Animals that have one or two copies of the mutation can pass the mutation on to future generations.

Mutation: Deletion, COL9A2 gene; del. 1267bp including exon1

Medical systems: Skeletal, oculaire

Breeds: American Eskimo Dog, American Staffordshire Terrier/Amstaff, Samoyed, Siberian Husky

Age of onset of symptoms: 4 to 6 weeks

Oculoskeletal Dysplasia 2 is a developmental genetic disease of Samoyeds involving short-limbed dwarfism and ocular defects.  It is caused by a mutation in one of the collagen genes (COL9A2).  In addition to shortened limbs, blindness occurs at a young age as a result of malformed and detached retinas and cataracts.  The skeletal defects and severe eye problems are seen in the homozygous (double mutant) animal, while the carrier animal may show mild retinal anomalies but not the dwarfism.  A similar condition, called Oculoskeletal Dysplasia 1 can occur in Labrador Retrievers; this is caused by a different mutation in another one of the collagen genes.

 

References:

OMIA link: [1523-9615]

Donner J, Freyer J, Davison S, et al. (2023) Genetic prevalence and clinical relevance of canine Mendelian disease variants in over one million dogs.  PLoS Genet. 19(2):e1010651. [pubmed/36848397]

Iwabe S, Dufour VL, Guzmán JM, et al. (2020) Focal/multifocal and geographic retinal dysplasia in the dog-In vivo retinal microanatomy analyses. Vet Ophthalmol 23:292-304.  [pubmed/31746146]

Goldstein O, Guyon R, Kukekova A, et al. (2010) COL9A2 and COL9A3 mutations in canine autosomal recessive oculoskeletal dysplasia. Mamm Genome. 21(7-8):398-408.  [pubmed/20686772]