Von Willebrand disease type II (vWD II)

Von Willebrand disease is caused by a deficiency of plasmatic von Willebrand factor, which plays an important role in platelet adhesion and aggregation during blood clotting. Deficiency or impaired function of von Willebrand factor leads to bleeding conditions. Type II disorder is characterised by qualitative deficiency and functional anomalies of von Willebrand factor and is manifested by moderate to severe bleeding.

Causal missense mutation c.1657T>G in the VWF gene has been detected in Chinese Crested Dog, German Shorthaired Pointer and German Wirehaired Pointer.

Mutation that causes vWD II is inherited as an autosomal recessive trait. In sequence substitution of the amino acid A to G can be seen. That means the disease affects dogs with P/P (positive / positive) genotype only. The dogs with P/N (positive /negative) genotype are clinically without any symptom. They are genetically considered carriers of the disease (heterozygotes). In offspring of two heterozygous animals following genotype distribution can be expected: 25 % N/N (healthy non-carriers), 25 % P/P (affected), and 50 % N/P (healthy carriers). Because of high risk of producing affected offspring, mating of two N/P animals (carriers) can not be recommended.

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References:

Vos-Loohuis, M., van Oost, B.A., Dangel, C., Langbein-Detsch, I., Leegwater, P.A. : A novel VWF variant associated with type 2 von Willebrand disease in German Wirehaired Pointers and German Shorthaired Pointers. Anim Genet 48:493-496, 2017. Pubmed reference: 28696025