LAUSR

Patients with type 1 and type 2 von Willebrand disease (VWD) can be treated with desmopressin. Although a previous study has shown that the location of the causative VWF gene variant is associated with desmopressin response in type 1 VWD, the association between variants in the VWF gene and desmopressin response is not yet fully understood. Our primary aim was to compare desmopressin response in type 1 VWD patients with and without a VWF gene variant. Secondly, we investigated whether desmopressin response depends on specific VWF gene variants in type 1 and type 2 VWD. We included 250 patients from the WiN study; 72 type 1 without a VWF gene variant, 108 type 1 with a variant, 45 type 2A, 16 type 2M and 9 type 2N patients. VWF gene was analyzed with ion semiconductor sequencing and MLPA. Complete response to desmopressin was observed in all type 1 VWD patients without a variant, 64.3% of type 1 patients with a variant and 31.3% of type 2 patients (p<0.001). Despite a large inter-individual variability in desmopressin response, patients with the same variant had comparable desmopressin responses. For instance, in six type 1 patients with exon 4-5 deletion, mean VWF activity at 1 hour after desmopressin was 0.81 IU/mL with a coefficient of variation of 22.9%. In conclusion, all type 1 VWD patients without a VWF gene variant respond to desmopressin. In type 1 and type 2 VWD patients with a VWF variant, desmopressin response highly depends on the VWF gene variants.