Trapped Neutrophil Syndrome

Trapped neutrophil syndrome is an inherited immune disorder that severely impairs the ability of the Border Collies' immune system to fight infection.

Symptoms

Symptoms usually appear at an early age, between 6 and 12 weeks of age. Affected puppies are usually smaller than their littermates and suffer from chronic infections, which do not respond well to antibiotic treatment. There is developmental delay as a result of a compromised immune system. In more severe cases, craniofacial alteration is observed, the shape of the skull is elongated and narrow. The syndrome is characterized by myeloid hyperplasia and a low blood neutrophil count.

Disease Management

Unfortunately, there is no cure for neutrophil trapped neutrophil syndrome and management of the condition focuses on treatment of infections as they arise and supportive measures. Many puppies affected by the disease do not survive more than one year.

Genetic basis

This disease follows an autosomal recessive mode of inheritance. Autosomal recessive inheritance means that the dog, regardless of sex, must receive two copies of the mutation or pathogenic variant to be at risk of developing the disease. Both parents of an affected dog must carry at least one copy of the mutation. Animals with only one copy of the mutation are not at increased risk of developing the disease, but may pass the mutation on to future generations. Breeding between dogs carrying genetic variants that can cause disease, even if they do not show symptoms, is not recommended.

Technical report

Trapped neutrophil syndrome is an autosomal recessive disorder that has only been found in Border Collies. In this disease, the bone marrow is seen to produce neutrophils, but these are not transferred to the blood, where they are needed to fight infection. In other words, the neutrophils are trapped. The mutation responsible for the disease, called c.2893_2896del, is found in the VPS13B gene. This gene produces a protein responsible for the transport of vesicles within the cell and which plays a relevant role in the development of hematopoietic cells and the central nervous system.

Most affected breeds

Border Collie

Bibliography

Shearman JR, Wilton AN. A canine model of Cohen syndrome: Trapped Neutrophil Syndrome. BMC Genomics. 2011 May 23;12:258.