Von Willebrand Disease, Type 2

Alternative Names

  • VWD2
  • Von Willebrand Disease, Type II
  • VWD, Type 2
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WHO-ICD-10 version:2010

Diseases of the blood and blood-forming organs and certain disorders involving the immune mechanism

Coagulation defects, purpura and other haemorrhagic conditions

OMIM Number

613554

Mode of Inheritance

Autosomal dominant Autosomal recessive

Gene Map Locus

12p13.31

Description

Type 2 von Willebrand Disease (type 2 VWD) is characterized by a bleeding disorder associated with deficiency of Von Willebrand factor (VWF) as well as its functional anomalies.  This type accounts for 20-45% of all cases of VWD.  There are four subtypes of type 2 VWD known as; types 2A, 2B, 2M and 2N.  Three of these subtypes are associated with anomalies in the interaction of VWF with platelets and/or the subendothelium.  Type 2A is caused by VWF multimerization anomalies.  Type 2B occurs due to increased VWF affinity for platelets.  Type 2M occurs due to decreased VWF affinity for platelets.  Type 2N occurs due to decreased VWF affinity for factor VIII (FVIII).  Types 2A, 2B and 2M are characterized by mucocutaneous manifestations.  Patients with type 2N experience less spontaneous abnormal bleeding events than in the other forms of type 2 VWD.  

Preventative or curative treatment includes substitution therapy with purified human VWF.

Molecular Genetics

All subtypes of VWD2 are inherited in an autosomal dominant pattern.  However, some cases of type 2A and 2N have shown an autosomal recessive inheritance.  

VWD is caused by mutations in the VWF gene. Mutations in this gene lead to intracellular retention or rapid clearance of VWF from circulation. The level of VWD in blood group O is 25-35% lower than in non-O blood groups.  Therefore, individuals with blood group O are at a greater risk for developing VWD.

Epidemiology in the Arab World

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Other Reports

Egypt

See Saudi Arabia > El-Bostany et al., 2008

Saudi Arabia

El-Bostany et al. (2008) recruited 43 children and adolescents from Saudi Arabia and Egypt with various bleeding disorders to assess the prevalence of inherited bleeding disorders (IBD).  Their ages ranged from 1-18 years.  They also included 15 matched controls.  Extensive laboratory work-ups were made including complete blood count, coagulation studies and platelets functions.  A total of 12 patients were found to meet the criteria of VWD.  Multimeric analysis, used to determine the subtype of VWD, found that three of these patients had VWD type II.  The authors concluded that VWB was common in Egypt and Saudi Arabia and therefore, hematological screening ought to be considered routinely in children with family history of bruising or bleeding disorders.

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