Hereditary cataract / HC HSF4-1 (HSF4-related) - Dog

What does this test examine?

This genetic test analyses the HSF4 c.971del variant in Australian Shepherd and Miniature American Shepherd. The disorder is known as hereditary cataract, primary hereditary cataract, HC, PHC and inherited cataract. Cataract means that the normally clear lens becomes opaque, reducing the amount of light reaching the retina and impairing vision.

What does it mean for the dog?

HSF4 encodes a heat-shock transcription factor important for lens development and lens cells. When this variant is present, the lens can become cloudy at a young or adult age. Depending on breed, genotype and penetrance, cataracts can differ in age of onset, severity and progression. Affected dogs may see less clearly, move less confidently, show visible eye changes and become blind in severe cases.

Practical value of this test

• Breeders can identify dogs carrying the HSF4-1 variant before matings are planned.
• The test helps plan combinations more accurately, especially because one copy can already increase cataract risk.
• The result supports selection against inherited cataract without relying only on appearance or later eye problems.
• For owners, the result gives useful context for timely eye follow-up.

This variant is interpreted as autosomal dominant with incomplete penetrance: one copy increases risk, not every carrier develops cataract, and two copies create a higher-risk genotype.