http://repub.eur.nl/res/aut/37400/ List of Publications en http://repub.eur.nl/static-eur/img/logo.png http://repub.eur.nl http://repub.eur.nl/res/pub/27224/ 2009-06-01T00:00:00Z Mild type 1 von Willebrand disease (VWD) is characterized by low to variable penetrance of bleeding, a high (increased) prevalence of blood group O, von Willebrand factor (VWF) values around and above 30% with normal ratios of VWF:ristocetin cofactor activity (RCo)/VWF:antigen (Ag), VWF:collagen binding (CB)/VWF:Ag and factor VIII (FVIII):coagulant activity (C)/VWF:Ag. Within this group of patients, the combination of the C1584 mutation and blood group O is rather frequent. Patients with mild VWD type 1 present good/normal responses of FVIII:C and VWF parameters to desmopressin (DDAVP). With the exclusion of dominant VWD type Vicenza, type 1/2E, recessive 2N and dominant 2M, missense mutations in patients with mild VWD type 1 with normal multimers are mainly located in the regulatory sequence region, the D1/D2 propeptide region, the D′ VWF-FVIII binding site region and the D4, B1-B3 and C1-C2 domains but rarely in the D3, A1 or A2 domain. A new category of either dominant or recessive mild VWD type 1 due to mutations in the D4, B1-B3 and C1-C2 domains of the VWF gene consists of two groups: one group with mild VWD with normal VWF multimers and a second group with mild/moderate VWD with smeary multimer pattern. http://repub.eur.nl/res/pub/27226/ 2009-06-01T00:00:00Z Guidelines and recommendations for the acute and prophylactic treatment of bleeding in von Willebrand disease (VWD) patients with von Willebrand factor (VWF)/factor VIII (FVIII) concentrates should be based on the analysis of the content of VWF/FVIII concentrates and on pharmacokinetic studies in patients with different severity of VWD (type 1, type 2 or type 3). The VW/FVIII concentrates should be assessed using the parameters FVIII:coagulant activity (C), VWF:ristocetin cofactor activity (RCo), VWF:collagen binding and VWF multimeric patterns for the presence of large multimers to determine their predicted efficacy and safety in prospective management studies. As the bleeding tendency is moderate in VWD type 2 and severe in type 3 and because the FVIII:C levels are subnormal in type 2 but very low in type 3 VWD patients, new guidelines using VWF:RCo unit dosing for the acute and prophylactic treatment of bleeding episodes are proposed. Such guidelines should be stratified for the severity of bleeding, the type of surgery (minor or major) and also for the bleeding score in either VWD type 1, 2 or 3. http://repub.eur.nl/res/pub/36723/ 2007-01-01T00:00:00Z The current standard set of von Willebrand factor (VWF) parameters used to differentiate type 1 from type 2 VWD include bleeding times (BTs), factor VIII coagulant activity (FVIII:C), VWF antigen (VWF:Ag), VWF ristocetine cofactor activity (VWF:RCo), VWF collagen binding activity (VWF:CB), ristocetine induced platelet aggregation (RIPA), and analysis of VWF multimers in low and high resolution agarose gels and the response to DDAVP. The BTs and RIPA are normal in asymptomatic carriers of a mutant VWF allele, in dominant type 1, and in recessive type 2N VWD, and this category has a normal response of VWF parameters to DDAVP. The response of FVIII:C is compromised in type 2N VWD. The BTs and RIPA are usually normal in type Vicenza and mild type 2A VWD, and these two VWD variants show a transiently good response of BT and VWF parameters followed by short in vivo half life times of VWF parameters. The BTS are strongly prolonged and RIPA typically absent in recessive severe type 1 and 3 VWD, in dominant type 2A and in recessive type 2C (very likely also 2D) VWD and consequently associated with low or absent platelet VWF, and no or poor response of VWF parameters to DDAVP. The BTs are prolonged and RIPA increased in dominant type 2B VWD, that is featured by normal platelet VWF and a poor response of BT and functional VWF to DDAVP. The BTs are prolonged and RIPA decreased in dominant type 2A and 2U, that all have low VWF platelet, very low VWF:RCo values as compared to VWF:Ag, and a poor response of functional VWF to DDAVP. VWD type 2M is featured by the presence of all VWF multimers in a low resolution agarose gel, normal or slightly prolonged BT, decreased RIPA, a poor response of VWF:RCo and a good response of FVIII and VWF:CB to DDAVP and therefore clearly in between dominant type 1 and 2U. The existing recommendations for prophylaxis and treatment of bleedings in type 2 VWD patients with FVIII/VWF concentrates are mainly derived from pharmocokinetic studies in type 3 VWD patients. FVIII/VWF concentrates should be characterised by labelling with FVIII:C, VWF:RCo, VWF:CB and VWF multimeric pattern to determine their safety and efficacy in prospective management studies. As the bleeding tendency is moderate in type 2 and severe in type 3 VWD and the FVIII:C levels are near normal in type 2 and very low in type 3 VWD patients. Proper recommendations of FVIII/VWF concentrates using VWF:RCo unit dosing for the prophylaxis and treatment of bleeding episodes are proposed and has to be stratified for the severity of bleeding, the type of surgery either minor or major and for type 2 and type 3 VWD as well.