Diagnosis and management of von Willebrand disease in The Netherlands.

In the Netherlands, specialized care for patients with a bleeding disorder, including hemophilia, von Willebrand disease (VWD), and allied disorders, is concentrated in 13 Hemophilia Treatment Centers. The Dutch Hemophilia Treaters Society, the Dutch Hemophilia Nurses' Society, and the Netherlands Hemophilia Patients Society collaborate to optimize management of patients with a bleeding disorder. A recently updated consensus guideline of hemophilia and allied bleeding disorders provide guidance on the current optimal diagnostic strategy and treatment of VWD. Genetic testing is not routinely performed in the Netherlands. Desmopressin (DDAVP) is the choice of treatment in VWD patients responsive to DDAVP, as determined by a test infusion. Coagulation factor concentrates are used in nonresponsive individuals, in case of a contraindication for DDAVP, or in type 2B and type 3 VWD. These concentrates are available for all patients in the Netherlands; however, these may only be administered in a Hemophilia Treatment Center or under the care of a Hemophilia Treatment Center. Recently a study on moderate and severe VWD (the Willebrand in Netherlands study) was initiated to obtain more insight on VWD diagnosis, treatment, and the burden of the disease.

[Von Willebrand disease in the Netherlands: the WiN study]. / De ziekte van von Willebrand in Nederland: de WiN-studie.

Von Willebrand disease is the most common inherited bleeding disorder and is characterised by mucocutaneous bleeding. Von Willebrand disease is caused by reduced levels or reduced function of von Willebrand factor. Depending on the cause, von Willebrand disease is distinguished into various types with their own characteristics and treatment options. The frequency and severity of bleeding in patients with von Willebrand disease is strongly determined by von Willebrand factor levels, factor VIII levels and the type of von Willebrand disease. Eighty-five percent of all adult females with von Willebrand disease reports menorrhagia. A high percentage have postpartum excessive blood loss (37% of all deliveries). The quality of life is reduced in patients with von Willebrand disease. Patients with von Willebrand disease have a reduced risk of arterial thrombosis such as a myocardial or cerebral infarction.

Effect of genetic variation in STXBP5 and STX2 on von Willebrand factor and bleeding phenotype in type 1 von Willebrand disease patients.

BACKGROUND: In type 1 von Willebrand Disease (VWD) patients, von Willebrand Factor (VWF) levels and bleeding symptoms are highly variable. Recently, the association between genetic variations in STXBP5 and STX2 with VWF levels has been discovered in the general population. We assessed the relationship between genetic variations in STXBP5 and STX2, VWF levels, and bleeding phenotype in type 1 VWD patients. METHODS: In 158 patients diagnosed with type 1 VWD according to the current ISTH guidelines, we genotyped three tagging-SNPs in STXBP5 and STX2 and analyzed their relationship with VWF:Ag levels and the severity of the bleeding phenotype, as assessed by the Tosetto bleeding score. RESULTS: In STX2, rs7978987 was significantly associated with VWF:Ag levels (bèta-coefficient (ß) = -0.04 IU/mL per allele, [95%CI -0.07;-0.001], p = 0.04) and VWF:CB activity (ß = -0.12 IU/mL per allele, [95%CI -0.17;-0.06], p<0.0001). For rs1039084 in STXBP5 a similar trend with VWF:Ag levels was observed: (ß = -0.03 IU/mL per allele [95% CI -0.06;0.003], p = 0.07). In women, homozygous carriers of the minor alleles of both SNPs in STXBP5 had a significantly higher bleeding score than homozygous carriers of the major alleles. (Rs1039084 p = 0.01 and rs9399599 p = 0.02). CONCLUSIONS: Genetic variation in STX2 is associated with VWF:Ag levels in patients diagnosed with type 1 VWD. In addition, genetic variation in STXBP5 is associated with bleeding phenotype in female VWD patients. Our findings may partly explain the variable VWF levels and bleeding phenotype in type 1 VWD patients.

Determinants of bleeding phenotype in adult patients with moderate or severe von Willebrand disease.

We performed a nation-wide cross-sectional study to evaluate determinants of bleeding symptoms in a large unselected cohort of adults with von Willebrand disease (VWD). VWD patients were included (n=664), based on lowest historically measured VWF:Ag and VWF:Act levels ≤30 U/dl. Menorrhagia (85%), cutaneous bleeding (77%), bleeding from minor wounds (77%) and oral-cavity bleeding (62%) occurred most frequently. Higher age was associated with a higher bleeding score (BS), determined according to Tosetto, in females. A 10 year increase in age was associated with 0.8 point (95% confidence interval [CI] 0.4-1.1) higher BS. Females had higher BS than males (median 12 vs. 10, p=0.012). BS differed significantly between VWD type 1, 2 and 3: median 9 (-2-31), 13 (-1-33) and 19.5 (1-35), respectively (p<0.001). BS was strongly associated with VWF and FVIII levels: individuals with VWF:Ag levels ≤10 IU/dl, VWF:Act ≤10 IU/dl and FVIII:C ≤10 IU/dl had, respectively, 5.3 point (95%CI 3.2-7.3), 4.3 point (95%CI 2.9-5.8) and 9.6 point (95%CI 6.5-12.7) higher BS, than those with levels >30 IU/dl. In type 3 patients 1 IU/dl FVIII:C decrease was associated with 0.6 point (95% CI 0.1-1.1) BS increase (p=0.021). In conclusion, in VWD patients the bleeding phenotype is strongly associated with type of VWD and VWF and FVIII levels.