Von Willebrand disease type III (vWD III) in Scottish Terriers

Von Willebrand disease is caused by a deficiency of plasma von Willebrand factor, which plays an important role in platelet adhesion and aggregation during blood clotting. Deficiency of von Willebrand factor or impairment of its function leads to bleeding conditions. Type III is the most severe form of the disease, in which very severe, life-threatening bleeding occurs. Von Willebrand factor is completely absent.

In Scottish terriers, the disease is caused by deletion c.255del in the von Willebrand factor (VWF) gene. The mode of inheritance of this mutation is autosomal recessive. This means that only individuals who inherit the mutated gene from both parents will develop the disease. Carriers of the mutated gene have normal blood clotting but may have lower levels of plasma von Willebrand factor. Although clinically healthy, they pass the mutation to their offspring. In the case of a mating between two heterozygous individuals, theoretically 25% of the offspring will be completely healthy, 50% of the offspring will be carriers and 25% of the offspring will inherit the mutated gene from both parents and will therefore be affected by the disease.

The genetic test can clearly reveal the genotype of the animal and is a useful tool for breeders to prevent unintentional breeding of affected puppies.

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References:

Venta, P.J., Li, J.P., Yuzbasiyan-Gurkan, V., Brewer, G.J., Schall, W.D.: Mutation causing von Willebrand's disease in Scottish terriers Journal of Veterinary Internal Medicine 14:10-19, 2000. Pubmed reference: 10668811