Von Willebrand Disease(vWD)

von Willebrand Disease(vWD)

Is glycoprotein synthesized mainly in endothelial cells & megakaryocytes, plasma and alpha granules of platelet.
vWF is a large multimeric glycoprotein. Concentration in plasma is 10 µg/ml
vWF contains 2050 amino acids.
The vWF is coded for by a gene near the tip of short arm of chrosome No 12 (similar size of F VIII gene).
- vWF is stored in Weible- Palade bodies.
Fuctions of vWF:-
-Mediates the adhesion of platelet to site of
vascular injury.
-Binds and stabilizes the procoaulant protein F VIII
Types:-
Partial quantitative deficiency.
1/ Type 1:- 1a, 1b, 1c. -70% of vWD.
- Auosomal dominant.
- vWF is low (I ml = 1 unit of Vwf:ag).
- Qualitative vWD.
2/ Type II : IIA, IIB, IIC, IID, IIE, IIF, IIG, IIH.
- 20-30 % of vWD.
Types:-
Type III(Total deficiency):-
Is the most severe form of vWF.
Affects very early of life.
- Clinically, the patients resemble hemophilics.
Clinical feature of vWD:-
- Severe bleeding tendency.
Bruising.
Epistaxes.
Bleeding from minor cuts.
Menorrhagia.
Bleeding after trauma and surgery.
- Types II, and III may cause severe and
potentially life threating.
- Type III type develop arthropathies (F VIII).
Lab diagnosis:-
Platelet count:- N
Bleeding time:- Prolonged.
Screening tests:-
PT:- N
APTT: prolonged.
TT: N.
vWF antigen: ↓ed (Immunoassay)

- Aggregation studies .
- Factor VIII level.

Acquired Vwd:-
Late-onset bleeding diathesis.
Endocrine abnormalities (Hyopthyrodism)
B-cell disorders.
Cardiac or vascular abnormalities.
Myeloproliferative disorders.
Drugs(valproate in seizur syndrome).