Successful Aortic Aneurysm Repair in a Woman with Severe von Willebrand (Type 3) Disease
Table 1
Classification of VWD (adapted from Laffan et al. [3]).
Type
Nature of VWF defect
Phenotypic changes
Mode of inheritance
1
Partial quantitative deficiency
(i) Includes rapid VWF clearance (e.g., VWF Vicenza) mutations (ii) Requires VWF:RCo/VWF:Ag ratio >0.6
(i) Predominately autosomal dominant inheritance when VWF <0.3 IU/dL (ii) VWF mutations with levels >0.3 IU/dL show variable penetrance
2
Qualitative defects
2A
Decreased VWF-dependent platelet adhesion with selective deficiency of HMWM
VWF:RCo/VWF:Ag ratio <0.6
(i) Mostly autosomal dominant
2B
Increased affinity for platelet GPIb
(i) VWF:RCo/VWF:Ag ratio <0.6 (ii) Typically associated with thrombocytopenia (iii) Should be distinguished from PT-VWD, by further testing by platelet agglutination tests or genetic testing (iv) Cases with normal VWF multimer and platelet count have been described
(i) Autosomal dominant
2M
Decreased VWF-dependent platelet adhesion without selective deficiency of HMWM
(i) This also includes defects of VWF collagen binding
(i) Autosomal dominant
2N
Markedly decreased binding affinity for FVIII
(i) VWF:RCo/VWF:Ag ratio <0.7 (ii) Should be distinguished from mild haemophilia A
(i) VWF:FVIII binding defects are more commonly due to compound heterozygote with a VWF null allele rather than the classical homozygous state
3
Virtually complete deficiency
(i) Equivalent to <0.03 IU/dL in most assays (ii) Bleeding symptoms in up to 48% of obligate carriers
