Identification of type 1 von Willebrand disease patients with reduced von Willebrand factor survival by assay of the VWF propeptide in the European study: molecular and clinical markers for the diagnosis and management of type 1 VWD (MCMDM-1VWD)

Abstract

The decreased survival of von Willebrand factor (VWF) in plasma has been implicated as a mechanism in a subset of type 1 von Willebrand disease (VWD) patients. We have previously reported that the ratio of plasma levels of VWF and its propeptide (VWFpp) can be used to identify patients with reduced VWF survival. In this study, we report the assay of VWFpp and VWF:Ag in 19 individuals recruited from 6 European centers within the MCMDM-1VWD study. Eight individuals had a VWF:Ag level less than 30 IU/dL. Seven of these patients had a robust desmopressin response and significantly reduced VWF half-life that was predicted by a markedly increased steady-state plasma VWFpp/VWF:Ag ratio. VWF mutations previously associated with reduced VWF survival were identified in each of the 7 individuals. Thus, a substantially increased ratio of steady-state VWFpp/VWF:Ag predicted a reduced VWF half-life in patients with markedly decreased VWF:Ag levels. These data indicate that a reduced VWF survival is found in a subpopulation of patients with type 1 VWD. The systematic assay of both plasma VWF and the VWF propeptide in moderately severe type 1 VWD patients may identify patients with a reduced VWF survival phenotype.

Figures

Figure 1

Plasma VWFpp and VWF:Ag levels in MCMDM-1VWD subset. VWF:Ag and VWFpp levels in patient plasma samples were measured by ELISA assays as described. The horizontal lines represent the median, 25th percentile, and 75th percentile VWF:Ag or VWFpp level. The open symbols denote patients with an increased clearance phenotype. VWF:Ag levels were decreased and varied considerably in these patients, while VWFpp levels fell within the normal range for most individuals and demonstrated less variability.

Figure 2

Time course of VWF:Ag and VWFpp after administration of desmopressin. (A) VWF:Ag levels were determined before (t = 0), 1, 2, and 4 hours after desmopressin administration. In most patients, VWF:Ag levels increased after desmopressin administration. While VWF:Ag levels in some patients diminished slowly over time, in other patients VWF:Ag levels rapidly decreased. (B) VWFpp levels were determined before (t = 0), 1, 2, and 4 hours after desmopressin administration. VWFpp levels in the plasma of all patients increased after administration of desmopressin and decreased over 4 hours.

Figure 3

Half-lives of VWFpp and VWF:Ag after administration of desmopressin. The half-lives of VWFpp and VWF were determined by calculation of the first-order rate constant for the elimination phase from the slope of the VWF:Ag or VWFpp concentration against time as described. The box extends from the 25th to 75th percentile, with a line at the median. The whiskers extend to the highest and lowest values determined. The half-life of VWFpp in most patients fell within the reported normal range. The half-live of VWF:Ag in individuals varied considerably ranging from markedly decreased to normal values. The median VWF half-life fell below the reported normal range.

Figure 4

Relationship between desmopressin response and steady-state plasma VWFpp/VWF:Ag ratio. The relative increase in VWF:Ag after desmopressin administration (t1/t0 (VWF:Ag)) and the ratio of steady-state plasma VWFpp/VWF:Ag level are shown for the type 1 VWD patient subset. The open symbols denote patients with an increased clearance phenotype. Correlation was found between desmopressin response and VWFpp/VWF:Ag ratio (r = 0.91, P < .001).

Figure 5

VWF multimer structure. Plasma VWF multimer pattern was determined by medium-resolution, 1.6% SDS-agarose gel electrophoresis. The patient ID is denoted above each lane and each sample is compared with normal pooled human plasma (N) that was run on the same gel. (A,B) Patients nos. 12 and 13 have R1205H/M740I mutations in VWF and diminished VWF multimer satellite bands. (C) Patient no. 7 has a C1130G VWF mutation and lacks satellite bands. (D) Patient no. 9 has a C1130R mutation in VWF and lacks satellite bands. At steady state, VWF multimer satellite bands are nearly absent from the plasma of these individuals.