A family having type 2B von Willebrand disease with an R1306W mutation: Severe thrombocytopenia leads to the normalization of high molecular weight multimers.

In type 2B von Willebrand disease (2B VWD), abnormal von Willebrand factor (VWF) spontaneously binds to platelets. This leads to the clearance of the high molecular weight multimers (HMWM) of VWF and results in thrombocytopenia. Herein we report a family of 2B VWD with an R1306W mutation which caused thrombocytopenia with giant platelets. The most important finding in this study is dynamic changes in VWF values in association with platelet counts. When the proband (2 years of age) had severe thrombocytopenia, his HMWM were normal, however, hematological examination showed a low level of VWF and a lack of HMWM after platelet count recovered. His affected sister also exhibited similar phenomenona. These results suggest that the severe thrombocytopenia leads to decreased clearance of VWF HMWM and restoration of VWF HMWM in plasma. We must consider 2B VWD in the case of recurrent thrombocytopenia following infection or other stress condition.