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Von Willebrand Disease (VWD)
Part 1: NHLBI Diagnosis Guidelines

Introduction & Clinical Assessment Recommendations



VWD Classification — ISTH1,2

Slide 6

May 2011

VWD is classified on the basis of criteria developed by the VWF Subcommittee of the International Society on Thrombosis and Haemostasis (ISTH) in 1994 and revised in 2006. VWD is classified into 3 major categories: Type 1 VWD reflecting partial quantitative VWF deficiency; Type 2 VWD reflecting qualitative VWF deficiency; and Type 3 VWD defined as total VWF deficiency. Type 1 VWD is the most common form and is of variable severity, whereas type 3 VWD is rare. Type 2 VWD has 4 variants or subtypes: Type 2A VWD, the most common, has decreased VWF-dependent platelet adhesion caused by deficiency of the high molecular weight multimers (HMWM) of VWF; Type 2B VWD reflects increased affinity of VWF for platelet GP Ib, resulting in deficiency of high molecular weight multimers of VWF and is often accompanied by thrombocytopenia; Type 2M VWD has decreased VWF-dependent platelet adhesion NOT caused by deficiency of high molecular weight multimers; and Type 2N VWD reflects markedly decreased VWF binding affinity for factor VIII. Laboratory features of these VWD subtypes will be discussed in more detail later in Part 2 of this presentation.

VWD Classification — ISTH1,2

 


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