von Willebrand's Disease Type II (RESEARCH ONLY) Overview
von Willebrand's Disease Type II (RESEARCH ONLY)
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The original paper by Donner et al (2016); found this mutation to be polymorphic in several breeds, suggesting that it is not the causative variant. This result is not recommended for breeding decisions.
Category: Haemolymphatic - Associated with the blood and lymph
Gene: von Willebrand factor (vWF) on Chromosome 27
Variant Detected: Base Substitution c.4937A>G p.Asn883Ser
Severity: Scale 4 has a high degree of severity. It generally causes a decreased quality of life and may also decrease the life expectancy.
Mode of Inheritance: Autosomal Recessive
Test Overview: Von Willebrand’s disease is the most common inherited bleeding disorder in dogs and occurs when there is a lack of functional von Willebrand factor. Von Willebrand factor is needed for the normal adhesion of platelets and for normal blood clotting to occur. There are 3 types of von Willebrand’s disease, and type II disease occurs when there is structurally abnormal von Willebrand factor in the blood of affected animals. This is a recessive disorder and is a fairly rare and severe form of von Willebrand’s disease. Because the von Willebrand factor is structurally abnormal, it will not function as it is supposed to in the process of blood clotting. This type of von Willebrand’s disease leads to severe bleeding disorders and episodes of bleeding. Diagnosis may be suspected in a dog that has a bleeding problem but a normal PT and APTT, and can be confirmed by DNA testing for the mutation that causes the disease. Treatment may involve supportive care as an inpatient in hospital, as well as blood and/or plasma transfusions to provide functioning clotting factors. Care must be taken that affected dogs do not play roughly, suffer trauma from falls or jumping from heights, and that veterinarians are always aware of their condition. However severe episodes of bleeding that can be life-threatening may occur regardless.
Recommended Screening: 1. DNA testing of all breeding animals performed prior to breeding – e.g. at 1 year of age. 2. Recommend DNA testing prior to any surgery (e.g. desexing). Can perform DNA test on puppies (e.g. at 8-12 weeks). 3. Alternatively recommend coagulation testing with BMBT (not PT/APTT) prior to desexing or routine surgery (As DNA test available for a few breeds only)
Research Citation(s): Kramer, JW. et al. A von Willebrand’s Factor Genomic Nucleotide Variant and Polymerase Chain Reaction Diagnostic Test Associated with Inheritable Type-2 von Willebrand’s Disease in a Line of German Shorthaired Pointer Dogs (2004) Vet Pathol 41;221-228.
Associated Breed(s): Border Collie, Mixed Breed, German Shorthaired Pointer, Collie Rough, Collie Smooth, German Wirehaired Pointer,