Background: Von Willebrand disease (vWD) is the most common congenital bleeding disorder caused by quantitative or qualitative deficiencies of von Willebrand factor(vWF). There are no difficulties in diagnosis type I and type III of vWD by screening tests while subtypes IIA IIB, IIM, IIN require additional tests including multimer analysis. The existing techniques for analysis the multimer structure of vWF are manual, complicated, non-standard and time consuming.

Aims: Evaluate diagnostic capabilities of new automated method, vWF multimer screening assay.

Methods: 30 children with vWD, 15 with Acquire von Willebrand Syndrome(aVWS) and 8 healthy donors as a control group were enrolled in this study. To diagnosis vWD von Willebrand factor antigen(vWF Ag); ristocetin cofactor activity(VWF:Rco); Collagen Binding(VWF:CB); Ristocetin-Induced Platelet Aggregation(RIPA); Factor VIII clotting activity(FVIII:C);Factor VIII Binding Activity(vWF:FVIIIb) were performed. Multimer analysis was carried out using the commercial HYDRAGEL5 von Willebrand Multimers kit on semi-automatic gel electrophoresis instrument, HYDRASYS(SEBIA).

Results: The samples from control group have 9-12 bands of vWF multimers with the same distribution as control plasma; 13 patients with type I vWD have proportional decrease in the intencity of the bands with preservation of the normal distribution of the bands; 3 patients with type III vWD have complete absence of multimers on the gel. Multimer analysis in 9 cases shows the absence of HMW multimer bands 5 of them with increase RIPA(type IIB), 4-without(type IIА). In other 5 patients the distribution of vWF multimers was normal against the changes in functional properties of vWF(IIM,N); 15 children with aVWS also showed normal distribution of vWF multimers.

Conclusions: Multimer analysis allows the visualization of multimers in various types of von Willebrand disease. The method is easy to perform and can be useful for classification of the subtype of vWD. But only full test panel including genetic tests will allow the classification of vWD type with high precision.

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ISTH Congress Abstracts - https://abstracts.isth.org/abstract/multimer-analysis-in-von-willebrand-disease-diagnosis-the-experiency-of-use/