Possibly relevant human trait(s) and/or gene(s)s (MIM numbers): 614284 (trait) , 120260 (gene)

Mendelian trait/disorder: yes

Mode of inheritance: Autosomal Recessive

Considered a defect: yes

Key variant known: yes

Year key variant first reported: 2010

Species-specific symbol: osd2; drd2

Species-specific description: Oculoskeletal dysplasia is a collagen disorder characterized by short-limbed dwarfism, particularly of the forelimbs, and vitreous dysplasia with associated retinal detachment and cataracts. A genetic test is available.

History: This disorder was first characterized in the Samoyed by Meyers et al (1983).

Inheritance: Obligate heterozygotes do not have skeletal lesions but may exhibit mild ocular lesions (Goldstein et al., 2010).

Mapping: CFA15

Molecular basis: The causative mutation is a 1,267 bp deletion that eliminates part of the 5’UTR, all of exon 1 and part of intron 1, which likely causes mRNA degradation and absence of COL9A2 protein (Goldstein et al., 2010).

Clinical features: Signs may be noticeable as early as 4 to 6 weeks of age (Goldstein et al., 2010). Affected dogs have short-limbed dwarfism and vitreous dysplasia. Associated ophthalmic lesions include retinal detachment and cataracts. The forelimbs are most noticeably affected, particularly the short radius and ulna, which subsequently develop curvature with varus/valgus deformities (Meyers et al., 1983). In pups, the dome of the cranium is often pronounced and there is moderate excessive exotropic strabismus. Some, but not all, carriers have vitreal stands, focal retinal folds or plaques of retinal dysplasia (Goldstein et al., 2010).

Pathology: There is a range of ocular defects, but the most consistent findings are cortical equatorial cataracts and vitreal liquefaction (Goldstein et al, 2010).

Control: Parents and siblings of affected dogs should be tested. Breeding of affected or carrier dogs is not recommended.

Genetic testing: There is a test available to detect the causative mutation. Dogs cannot be reliably identified by clinical signs alone, so dogs suspected to have oculoskeletal dysplasia should be tested.

Breed: Samoyed.

Associated gene: