Primary ciliary dyskinesia / PCD (STK36-related) - Australian Shepherd

What does this test examine?

This genetic test analyses the STK36 c.2868-1G>A variant in the Australian Shepherd. The disorder is known as primary ciliary dyskinesia, Primary Ciliary Dyskinesia, PCD and, in older or broader terminology, sometimes as immotile cilia syndrome. The result shows whether the dog carries zero, one or two copies of the tested variant.

The STK36 gene is important for the normal structure and function of motile cilia. These cilia help move mucus, dust and bacteria out of the airways. When this function is disrupted, the natural clearance of the nose, trachea and bronchi can be impaired.

What does PCD mean?

PCD is an inherited ciliopathy in which cilia move poorly or have an abnormal structure. Affected dogs can develop recurrent respiratory problems from a young age, including sneezing, nasal discharge, yellow-green nasal discharge, coughing, bronchitis or pneumonia. Signs may improve temporarily after treatment, but often return because the underlying ciliary function is genetically impaired.

Cilia also play a role in other organs, including the reproductive tract. PCD can therefore be relevant not only for respiratory health, but also for fertility and breeding plans. This test specifically assesses the STK36 variant described in Australian Shepherds.

Inheritance and result

The trait follows autosomal recessive inheritance. A clear dog does not carry the tested variant. A carrier has one copy and is usually clinically healthy, but can pass the variant to offspring. A dog with two copies has the affected genotype that causes PCD.

• GG - no copy of the tested variant detected.
• GA - carrier: one copy of the tested variant detected.
• AA - affected genotype: two copies of the tested variant detected.

Practical value of this test

For breeders, this test is especially useful because carriers can look completely normal. Without DNA testing, a carrier may remain unnoticed in breeding and a mating between two carriers can produce puppies affected by PCD. The result helps plan combinations, manage carriers responsibly and greatly reduce the risk of affected puppies without unnecessarily excluding valuable lines.

For owners and veterinarians, the test provides clarity when an Australian Shepherd has repeated respiratory problems from a young age. A genetic result can help place recurrent signs in context and supports targeted screening of relatives or breeding animals.