Autoimmune lymphoprolifeative syndrome (ALPS)

Autoimmune lymphoproliferative syndrome (ALPS) is a genetic disorder affecting the regulation of the immune system. Normally, immune cells that are no longer needed or are improperly regulated are selectively eliminated through programmed cell death (apoptosis). This process is essential for maintaining balance within the immune system and preventing excessive immune responses.

In Boerboel dogs, an association has been established between a genetic variant in the FAS gene and the development of ALPS. In affected dogs, immune system regulation is disrupted, causing certain T lymphocytes to accumulate in various organs.

As early as 8 to 15 weeks of age, this leads to markedly enlarged, non-painful lymph nodes and a visibly enlarged abdomen due to severe enlargement of the spleen. In addition, other non-specific symptoms have been observed in affected puppies, including anaemia (a reduced red blood cell count), thrombocytopenia (a reduced platelet count), lethargy and weakness, loss of appetite, recurrent diarrhoea, fever, and occasionally abnormal breathing sounds and coughing. The severity of clinical signs may vary.

As the enlargement of the lymph nodes and changes in the lymphocyte population can resemble lymphoma, a thorough veterinary examination is required.

The genetic variant is a duplication in the FAS gene, which encodes the FAS receptor (CD95), a protein that plays a central role in initiating programmed cell death in immune cells. The variant is inherited in an autosomal recessive manner.

Genetic testing enables the identification of the described variant regardless of whether clinical signs are present. This allows clinically healthy carriers to be identified and taken into account in breeding decisions. In the case of recessively inherited disorders, carriers do not necessarily need to be excluded from breeding, provided they are only mated with genetically clear dogs.