Poor response to 1-desamino-8-D arginine vasopressin (DDAVP) test in a patient with von Willebrand disease type 2M (VWD2M) with p.Glu1549Lys mutation.

Toronto

Congreso; XXV Congress of the International Society on Thrombosis and Haemostasis; 2015

ISTH

Poor response to 1-desamino-8-D arginine vasopressin (DDAVP) test in a patient with von Willebrand disease type 2M (VWD2M) with p.Glu1549Lys mutation Background: Type 2 VWD is subdivided into categories (2A, 2B, 2N and 2M) based on structural and functional abnormalities. Type 2M VWD has been reported to show a variable response to DDAVP depending on the mutation. In our country there is no information on the response to DDAVP in patients with VWD2M.Aims: To describe the phenotypical data of response to DDAVP test in a patient with VWD2M which carries the mutation p.Glu1549Lys in von Willebrand factor (VWF).Patient and Methods: Patient was a 21 yo male who had prolonged bleeding after tooth extractions and a lifelong history of easy bruising and epistaxis. History was positive in his father and elder sister. Hematological examination revealed a normal platelet count and prothrombin time but a prolonged aPTT (47 sec; normal range: 26-37sec). Low VWF:RCo activity but normal VWF:Ag were observed (0.30 and 0.53 IU/ml respectively; normal values: 0.50-1.50 IU/ml). He also showed a decreased platelet aggregation induced with ristocetin (1.25 mg/ml). DDAVP test (0.3 µg/kg i.v.) was performed. Platelet count and levels of factor VIII, VWF:RCo and VWF:Ag were determined before and 60 min after infusion. Direct sequence of exon 28 was carried out using genomic DNA.Results: Before and 60 min after drug administration, platelet count was: 173 and 162 x109L-1, factor VIII: 0.26 and 0.58 IU/ml, VWF:Rco: 0.20 and 0.23 IU/ml and VWF:Ag: 0.48 and 0.68 IU/ml, respectively. A heterozygote c.4545G>A change resulting in a p.Glu1549Lys mutation was found. Conclusion: There is a lack of response to DDAVP in our patient with vWD2M and pGlu1549Lys mutation. A correlation of response to DDAVP with other mutations can only be speculated and further studies are needed to resolve this issue.