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New variant of von Willebrand disease type II with markedly increased
levels of von Willebrand factor antigen and dominant mode of inheritance:
von Willebrand disease type IIC Miami
MR Ledford, I Rabinowitz, JE Sadler, JW Kent and F Civantos
Department of Pathology, University of Miami School of Medicine, FL.
A variant of von Willebrand disease (vWD) was identified in six members of
a kindred spanning four generations. The proband was a 46-year-old woman
with a lifelong history of bleeding, a prolonged bleeding time (> 15
minutes), markedly elevated von Willebrand factor (vWF) antigen (vWF:Ag =
2.09 U/mL), slightly reduced ristocetin cofactor activity, and a plasma vWF
multimer pattern similar to that of vWD type IIC. Similar findings were
observed in her three children, mother, and brother. In affected family
members, platelet and plasma vWF multimer patterns were discrepant with
higher molecular weight multimers observed in platelet vWF. Following a
1-Des-amino-8-D-arginine vasopressin (DDAVP) challenge, the proband failed
to normalize her bleeding time even though vWF: Ag rose by 70% and higher
molecular weight multimers were increased slightly. Genetic studies were
consistent with autosomal dominant inheritance of a mutation within the vWF
gene. By sequencing of cloned genomic DNA, mutations were excluded in exons
4, 5, 14, and 15, which encode regions of the vWF propeptide proposed to be
important in multimer biosynthesis. Mutations also were excluded in exons
28 to 31, which encompass the known mutations that cause vWD types IIA,
IIB, and B. This new variant of vWD, characterized by autosomal dominant
inheritance, a qualitative defect that resembles vWD type IIC, and
increased plasma vWF:Ag, was tentatively designated vWD type IIC Miami.
Volume 82,
Issue 1,
pp. 169-175,
07/01/1993
Copyright © 1993 by The American Society of Hematology
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Two Cys residues essential for von Willebrand factor multimer assembly in the Golgi
PNAS,
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J. J. Michiels, Z. Berneman, A. Gadisseur, M. van der Planken, W. Schroyens, A. van de Velde, and H. van Vliet
Classification and Characterization of Hereditary Types 2A, 2B, 2C, 2D, 2E, 2M, 2N, and 2U (Unclassifiable) von Willebrand Disease
Clinical and Applied Thrombosis/Hemostasis,
October 1, 2006;
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397 - 420.
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