Assay principle and interpretation of available test results for the subclassification of VWD types
| . | Principle . | Interpretation of results . |
|---|---|---|
| VWF multimers | Two-dimensional immunoelectrophoresis followed by labeling and autoradiography | • All sizes present: normal, type 1, 2M, 2N • Absent: type 3 • Absence of large and intermediate forms: type 2A • Absence of large forms: 2B |
| Collagen binding (VWF:CB) | Functional assay measuring the ability of VWF to bind collagen I and III | • Decreased proportional to VWF:Ag in type 1 • Absent in type 3 • Low with decreased ratio to the VWF:Ag in type 2A and 2B • Normal or decreased proportional to VWF:Ag |
| Ristocetin-induced platelet aggregation | Measures the ability of patient platelets to agglutinate in the presence of multiple concentrations of ristocetin | • Present agglutination at low doses of ristocetin and increased at standard doses in type 2Ba |
| Factor VIII binding (VWF:FVIIIB) | Measures VWF activity to bind FVIII | •Low in type 2N |
| . | Principle . | Interpretation of results . |
|---|---|---|
| VWF multimers | Two-dimensional immunoelectrophoresis followed by labeling and autoradiography | • All sizes present: normal, type 1, 2M, 2N • Absent: type 3 • Absence of large and intermediate forms: type 2A • Absence of large forms: 2B |
| Collagen binding (VWF:CB) | Functional assay measuring the ability of VWF to bind collagen I and III | • Decreased proportional to VWF:Ag in type 1 • Absent in type 3 • Low with decreased ratio to the VWF:Ag in type 2A and 2B • Normal or decreased proportional to VWF:Ag |
| Ristocetin-induced platelet aggregation | Measures the ability of patient platelets to agglutinate in the presence of multiple concentrations of ristocetin | • Present agglutination at low doses of ristocetin and increased at standard doses in type 2Ba |
| Factor VIII binding (VWF:FVIIIB) | Measures VWF activity to bind FVIII | •Low in type 2N |
Indistinguishable from platelet-type VWD caused by gain-of-function variants in GPIb.