To cite this article: Sanders YV, van der Bom JG, Isaacs A, Cnossen MH, de Maat MPM, Laros-van Gorkom BAP, Fijnvandraat K, Meijer K, 95% CI À7.9 to À0.6) and lower VWF:Act (À5.7 IU dL À1 per allele; 95% CI À10.9 to À0.5). In type 2 patients, none of the SNPs was associated with VWF levels. None of the genetic variants was associated with bleeding score. Conclusions: Genetic variations in STXBP5 and CLEC4M are associated with VWF level variation in type 1 VWD, but not in type 2 VWD. This study increases our understanding of the pathophysiology of VWD, and provides a further indication of the involvement of STXBP5 and CLEC4M in determining VWF levels in VWD.