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Von Willebrand Disease Type 2 (VWD2)
| Acronym: | VWDII, VWD2 |
| Gene: | VWF |
| Mutation: | c.4937A>G |
| Inheritance: | Autosomal recessive |
| Sample type: | CHS (Cheek Swab), WBE (Whole Blood EDTA) |
Genetics and characteristics
Von Willebrand disease (VWD) is a bleeding disorder of variable severity that results from a quantitative or qualitative defect in the von Willebrand factor (VWF). On vascular injury, VWF mediates platelet adhesion to exposed subendothelium and is involved in platelet-to-platelet aggregation. The disease is the most common hereditary bleeding disorder and it is genetically and clinically heterogeneous. Clinical signs of the disease include spontaneous bleeding from mucosal surfaces and excess blood loss after surgery or trauma. Three clinical types, 1, 2, and 3, have been described.
Von Willebrand disease type 2 dogs have a qualitative defect in vWF, lacking high-molecular-weight multimers. Affected dogs have a severe bleeding tendency. Von Willebrand disease type 2 is inherited recessively in dogs. Testing of affected dogs can be done by Von Willebrand disease type 2 antigen testing or by coagulation assays, but these procedures yield variable results. This variability makes it difficult for breeders to use this information to eliminate the disease-causing allele from their lines. Thus, it is highly desirable that DNA tests are run to get definitive answers.
Results Reported As
Test Result |
Interpretation of test result |
CLEAR |
Tested mutation was not detected in animal with „clear“ result. Animal tested as clear has wild-type allele in homozygous state (i.e. two pairs of healthy alleles). It will not develop disease caused by tested mutation.* It will pass only wild-type allele to its offspring. |
CARRIER |
Tested mutation was detected in animal with „carrier“ result. Animal tested as carrier has one wild-type and one mutation allele, it is in heterozygous state. It will not develop disease caused by tested mutation.* It can pass wild-type or mutation allele to its offspring. |
AFFECTED |
Tested mutation was detected in animal with „affected“ result. Animal tested as affected has two copies of mutation alleles affecting the gene. It is likely the animal will experience a genetic disorder due to this mutation.** It will pass only mutation allele to its offspring. |
*Test excludes only tested mutation but not possible unknown mutations or factors that can lead to similar condition/symptoms.
** Potential unknown mutations or multiple other factors can possibly affect the likelihood of experiencing a genetic disorder.
References:
Moser, J., Meyers, K.M., Meinkoth, J.H., and Brassard, J.A. (1996). Temporal variation and factors affecting measurement of canine von Willebrand factor. American Journal of Veterinary Research 57, 1288–1293.
Venta, P.J., Li, J., Yuzbasiyan-Gurkan, V., Brewer, G.J., and Schall, W.D. (2000). Mutation causing von Willebrand’s disease in Scottish Terriers. J. Vet. Intern. Med. 14, 10–19.