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Wednesday, 19/09/2018, 10:14:26 PM
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von Willebrand's Disease


von Willebrand's Disease -By A. Dasgupta ,MBBS(Std)

What is it ?
   von Willebrand's Disease is a very common hereditary bleeding disorder caused by Qualitative or Ouantitative defects involving the factor VIII-von Willebrand Factor complex.
 
What is the occurance of this disease ?
  1 in 800-1000 individuals of either sex.
 
Pathophysiology :
   vWD is an Autosomal disorder mainly due to Platelet abnormalities and in severe cases,due toCoagulation Disorders as well.
   vWF is a protein consisting of a series of multimers.It is synthesized by the Macrophages &Mononuclear Phagocytic System being coaded by a gene in Chromosome 12.It serves important functions in blood:

1)It serves as a plasma carrier of Factor VIII by forming the complex.
2)It increases the half-life of Factor-VIII in blood.
3)It binds with Collagen & Platelets via receptors IB-IX & IIb-IIIa to favor Platelet Adhesion & Aggregation
 
    so,deficiency or defect in vWF causes --------
1)Platelet function Disorders giving rise to vWD.
2)Decreased Half-life[from 12 hours to 2.4 hours] of F-VIII which may cause F-VIII Deficiency leading to graver conditions.
 
Clinical manifestations:
1)in mild cases,Bleeding occurs only after surgery or trauma.
2)Moderate to severe cases are characterized by petechie,purpura,epistaxis,oral mucosal & g.i.bleeding,menorrhagia etc.
3)in very severe cases,F-VIII deficiency may cause Haematoma Formation,Haemarthrosis etc.
 
Types:
   about 20 variants of vWD have been detected,which are broadly categorized into 3 types:Type-I,Type-II & Type-III. Type-III & Type-IIC are autosomal recessive while the rest are autosomal dominant.

TYPE-I:    it's a mild disorder due to missensed genetic mutation & characterized by mild to moderate reduction in plasma vWF.[activity 50%]Synthesis of vWF is normal but release of multimers is inhibited.

TYPE-II:    it's a qualitative disorder due to missensed genetic mutation & characterized by normal or near normal levels ofdysfunctional vWF.
      TYPE-IIa: has a deficiency of High & Medium mol.wt. vWF multimers due to secretory inability or increased proteolysis.
      TYPE-IIb: due to inappropriate binding of vWF to Platelets.
      TYPE-IIN: due to defect in F-VIII Binding Site of vWF.

TYPE-III:   It's a very sveere but least common disorder due to Deletion & Frame-shift mutation. The patient shows no detectable vWF activity & may have Sufficiently low f-VIII levels.
 
Laboratory diagnosis: 

i)Bleeding time: Prolonged
ii)Prothrombin time:Normal
iii)Platelet Count: Normal
iv)Clotting time: Prolonged
v)Activated Partial Thromboplastin Time: Prolonged
vi)Plasma vWF:Reduced
 
Treatment of this disease : 

1)Mild bleeding is managed with DDAVP or Desmopressin.
2)Severe bleeding can be controlled by intravenous cryoprecipitates.
3)for oral surgical procedures,EACA is given orally.
4)Menorrhagia,if present,is managed with Hormonal suppression.



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