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Hématologie

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von Willebrand disease Volume 17, issue 4, Juillet-Août 2011

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Service d’hématologie biologique, Hôpital Antoine-Béclère, Groupe Hospitalier Paris-Sud, 157 rue de la Porte-de-Trivaux, 92140 Clamart, Inserm U770, Université Paris 11, Le Kremlin-Bicêtre, Institut d’hématologie-transfusion, Hôpital cardiologique, Lille, Centre national de référence de la maladie de Willebrand (CRMW), Clamart et Lille

Von Willebrand disease (VWD) is an inherited bleeding disorder caused by a genetic defect (autosomal transmission, mostly dominant) of the concentration, structure or function of von Willebrand factor (VWF), a multimeric glycoprotein involved in both primary hemostasis (mediator of platelet adhesion and aggregation) and coagulation (carrier protein for factor VIII (FVIII)). VWD is characterized by a great clinical, biological and molecular heterogeneity secondary to the complex structure and functions of VWF. The prevalence of all forms of VWD is about 1% of the general population while the prevalence of the most symptomatic forms (bleeding episodes leading to a hospital management) is about 0.01%. The diagnosis of VWD relies on both clinical symptoms (skin and mucosal bleedings±visceral and joins bleeding in the most severe form) and biological data (panel of miscellaneous phenotypic and genotypic testing) which allow identifying VWD type. Indeed, VWD is classified in 3 main types: type 1 relies on a partial quantitative deficiency of VWF and represents 50 to 75% of cases, type 3 consisting in a total quantitative deficiency of VWF recessively inherited, is the most severe form and represents 5% of cases, type 2 relies on qualitative deficiencies of VWF and represents 20 to 45% of cases. Within type 2 VWD, variants 2A, 2B and 2M have in common an abnormal interaction of VWF with platelets and/or the subendothelium while variant 2N is characterized by a defective binding of VWF to FVIII. The identification of the accurate type of VWD is optimized by the phenotype/genotype confrontation; it is crucial for the patients’ management in terms of therapeutic options which mainly rely on desmopressin and/or VWF concentrates. In France, a National Reference Center for von Willebrand Disease (CRMW) was created in 2006 through the National Plan for Rare Diseases. The CRMW offers a national service dedicated to VWD management, thanks to both a clinical counseling and a biologic platform for phenotype and genotype diagnosis.