Granulocyte hyposegmentation in the Australian Shepherds

Granulocytes are a type of white blood cell whose main function is to help the body fight against infection. Their morphology, e.g. segmentation of the nucleus, is an indicator of various diseases. Hyposegmentation is a condition in which the nuclei of granulocytes have fewer segments than normal, resulting in a change in their shape and possibly their function.

In Australian Shepherds, this condition is caused by the c.191+1G>A mutation in the LMBR1L gene. Due to the similarity with the human Pelger-Huët anomaly, autosomal semidominant inheritance with embryonic lethality in affected homozygotes was initially assumed. More recent studies suggest that this is an autosomal recessive mutation that is relatively common in the Australian Shepherd population and is unlikely to be associated with any serious health problems.

Autosomal recessive inheritance means that hyposegmentation develops only in individuals who inherit the mutated gene from both parents. A genetic test can identify the genotype of an animal and is a useful tool for breeders to prevent unintentional breeding of affected puppies.

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References:

Lourdes Frehner, B., Christen, M., Reichler, I.M., Jagannathan, V., Novacco, M., Riond, B., Peters, L.M., Suárez Sánchez-Andrade, J., Pieńkowska-Schelling, A., Schelling, C., Kipar, A., Leeb, T., Balogh, O. : Autosomal recessive hyposegmentation of granulocytes in Australian Shepherd Dogs indicates a role for LMBR1L in myeloid leukocytes. PLoS Genet 19:e1010805, 2023. Pubmed reference: 37347778