Attendance was approximately 200.

Dr. Augusto B. Federici discussed a proposal for an international registry on acquired von Willebrand syndrome (AVWS). Based on the preliminary analysis of responses to a survey questionnaire on AVWS, mailed by Dr. Federici and Dr. Jacob Rand, creation of a Working Party on AVWS was APPROVED by voice vote.

Dr. William C. Nichols presented an update on the VWD mutation and polymorphism databases. These resources continue to be used heavily. In the absence of specific financial support, the currency and accuracy of the database is dependent on voluntary entries by the scientific community. Efforts are underway to incorporate the VWF database into other more general mutation database projects.

Dr. David L. Aronson discussed proposed labeling recommendations for plasma products for use in VWD. A survey of 38 treatment centers yielded 33 responses, 31 of which favored labeling factor VIII products for VWF content.

Dr. Mark J. Weinstein (Acting Chief, Hemostasis Laboratory, U.S. Food and Drug Administration) discussed the benefits and liabilities of using the ristocetin cofactor activity as a means of defining VWF activity and proposals for standardizing VWF-containing concentrates. These issues will be addressed in detail at a workshop on von Willebrand factor to be held at the National Institutes of Health on September 26, 1997. Members of the Working Party on VWF Assays will attend. A proposal was APPROVED by voice vote that manufacturers should be encouraged to meet the requirements to label Factor VIII products for treatment of VWD with VWF content. Measures to establish this practice will be considered by the Working Party on VWF Assays.

Dr. Dominique Meyer presented a report on the activities of a network of 32 hemostasis centers throughout France, supported by INSERM. Its aims are to improve the diagnosis of VWD, to assess the frequency of the different types of VWD, and to identify new mutations in the VWF gene.

Dr. Federici gave a progress report on the Italian Registry of VWD. A computer database was developed to collect information from 33 hemophilia centers at four-month intervals. An analysis of data for the first 637 patients from eight centers was presented.

Dr. Sadler reviewed the activities of the Subcommittee during 1995-1996 to develop consensus guidelines for the diagnosis of VWD type 1. The consensus guidelines for diagnosis of VWD type 1 were APPROVED for further evaluation through a retrospective collaborative international study by the Working Party on VWD Diagnosis.

Dr. Robert R. Montgomery chaired a session of the Working Party on VWF Assays. Dr. Trevor Barrowcliffe addressed issues concerning VWF standards, including the replacement of the current WHO plasma standard. In further discussion the topics considered were: (1) the production and distribution of VWF standards for plasma and concentrates; (2) the use of standards to evaluate assays for VWF:Ag, VWF:RCo, and multimers; and (3) the development of specific recommendations for the use of assays in diagnosis and product standardization.

Dr. Francesco Rodeghiero chaired a session of the Working Party on VWD Diagnosis. He proposed a collaborative international study to retrospectively assess the value of bleeding history and laboratory measurements in the diagnosis of VWD type 1. In response to a preliminary feasibility questionnaire, at least 20 centers around the world have agreed to participate so far. Dr. Alberto Tosetto briefly presented some methodological issues relating to the design of this study. Dr. Giancarlo Castaman discussed the relationship between phenotype and genotype based on available data.

Issues voted:

1. Creation of a Working Party on AVWS was APPROVED.

2. The proposal, that manufacturers should be encouraged to meet the requirements to label Factor VIII products for treatment of VWD with VWF content, was APPROVED by voice vote.

3. Consensus guidelines for diagnosis of VWD type 1 were APPROVED for further evaluation by the Working Party on VWD Diagnosis, through a retrospective collaborative international study.

4. A kit of VWF plasma and concentrate standards, and plasma samples from VWD subtypes and controls, will be assayed by collaborating laboratories to test the ability to diagnose VWD subtypes. This study was APPROVED by voice vote.

Completed projects:

C. Mazurier, D. Meyer
Factor VIII Binding Assay of von Willebrand Factor and the Diagnosis of Type 2N von Willebrand Disease. Results of an International Survey. Thrombosis and Haemostasis, vol. 76, 1996, p. 270.

Ongoing projects:

1. Issues relating to the labeling of factor VIII products with VWF content will be addressed in detail at a workshop on von Willebrand factor to be held at the National Institutes of Health on September 26, 1997. Members of the Working Party on VWF Assays will plan to participate.

2. The Working Party on VWF Assays will address the standardization and evaluation of laboratory tests for the labeling of blood products and for the diagnosis of VWD subtypes.

3. The Working Party on VWD Diagnosis will conduct a collaborative, international retrospective study of diagnostic criteria in VWD type 1.

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