Hyposegmentation of granulocytes / HG (LMBR1L-related) - Australian Shepherd

What does this test examine?

This genetic test analyses the LMBR1L variant c.191+1G>A for hyposegmentation of granulocytes in the Australian Shepherd. The trait is also known as HG, primary granulocyte hyposegmentation, granulocyte hyposegmentation, a Pelger-Huët-like blood picture and historically as Pelger-Huët anomaly in dogs. The test shows whether the dog is clear, a carrier or has two copies of the tested variant.

What does this trait mean?

Granulocytes are white blood cells. In HG, the nuclei of these granulocytes have fewer segments than usual. This can be visible on a blood smear and can resemble changes seen with other causes of granulocyte hyposegmentation.

In Australian Shepherds, the primary form is caused by a splice-site variant in LMBR1L. The primary genetic form is currently described mainly as a benign blood-cell morphology trait. Its practical value therefore lies not only in breeding selection, but also in correct interpretation of laboratory findings.

Practical value of this test

• shows whether an Australian Shepherd is clear, a carrier or genetically affected for the tested LMBR1L variant
• helps breeders distinguish carriers and affected dogs in lines where HG occurs
• gives veterinarians and owners context when a blood smear shows granulocyte hyposegmentation
• helps distinguish primary inherited HG from secondary causes such as inflammation, medication effects, bone marrow problems or other disease processes
• can reduce unnecessary concern and additional testing when the blood picture fits this known inherited variant

Who benefits from this test?

The test is especially useful for Australian Shepherd breeders, owners who want to understand the genetic background of a blood-cell finding and veterinarians who want to interpret granulocyte hyposegmentation more accurately. The result is also practical when selecting or purchasing breeding dogs, because carriers usually do not stand out but can still pass the variant on.

Inheritance and result

The trait is inherited as autosomal recessive. G/G means that the tested variant was not detected. G/A means that the dog is a carrier. A/A causes the tested HG blood-cell pattern with reduced nuclear segmentation of granulocytes.