Gray Collie syndrome / cyclic neutropenia (AP3B1-related) - Collie

What does this test examine?

This genetic test analyses the AP3B1 c.2401_2402insA variant in Collies. The disorder is known as Gray Collie syndrome, cyclic neutropenia and cyclic hematopoiesis. The name reflects the typical greyish coat colour that can occur in affected puppies together with a severe blood-cell disorder.

What does it mean for the dog?

AP3B1 is involved in intracellular transport in blood and immune cells. Two copies of the variant cause cyclic shortages of neutrophils, repeatedly weakening immune defence. Affected puppies may develop fever, infections, diarrhoea, poor growth, bleeding problems and episodes of serious illness. Carriers are usually healthy but can pass the variant on unnoticed.

Practical value of this test

• Rough and Smooth Collie breeders can identify carriers before matings are planned.
• The result helps avoid carrier-to-carrier matings, preventing puppies with two copies of this severe variant.
• In puppies from risk lines, the test can provide a fast genetic explanation when grey coat colour and recurrent infections are seen.

The condition is inherited as an autosomal recessive trait. One copy makes a dog a carrier; two copies cause Gray Collie syndrome / cyclic neutropenia.