Osteogenesis imperfecta / brittle bone disease (COL1A2-related) - Chow Chow

What does this test examine?

This genetic test analyses the COL1A2 c.936+1G>A variant in the Chow Chow. The condition is known as osteogenesis imperfecta, OI, brittle bone disease and a collagen-related skeletal disorder.

COL1A2 is involved in type I collagen. This collagen gives strength to bones, teeth and connective tissue. Disruption can make bones and teeth far too fragile from an early age.

What does this condition mean?

Osteogenesis imperfecta causes fragile bones and often abnormal teeth. Affected puppies can fracture easily, sometimes after limited pressure or normal play. Reduced growth, abnormal bone density, thin-walled or discoloured deciduous teeth, pain and stiff movement can also occur.

Severity differs between variants and breeds. In severe forms, signs may be visible in the first weeks or months of life. A DNA result records variant status before a dog is used for breeding.

Inheritance and result

The trait is inherited as autosomal dominant. One copy of the COL1A2 c.936+1G>A variant is sufficient for a genetically positive result.

What does the result mean?

• Clear (GG): the tested COL1A2 variant was not detected.
• Genetically positive (GA): one copy is detected and gives a genetically positive result.
• Genetically positive (AA): two copies are unusual, but mean that the dog is genetically positive for the tested variant.

Practical value of this test

• Shows whether the dog is clear, genetically positive or a carrier for the tested variant.
• Helps breeders avoid risky matings and prevent puppies with severe bone and tooth fragility.
• Provides certainty in young dogs that may still look normal but may later enter a breeding programme.
• Supports line management when fractures, brittle teeth, low bone density or OI occur in related animals.
• Makes communication with fellow breeders and puppy buyers more concrete because variant status is objectively known.

For breeding selection, this test is valuable because osteogenesis imperfecta can have a major impact on welfare, mobility and quality of life.