Investigations on the Importance and Prevalence of the Acquired von Willebrand Syndrome in Patients with Myeloproliferative Disease.

The acquired von Willebrand syndrome (AVWS) is a bleeding disorder, which is amongst others associated with myeloproliferative diseases. Its prevalence varies from 0,04–0,13% in literature. Typical laboratory findings such as a low VWF:RCo/VWF:Ag- Ratio, a prolonged aPTT, PFA and bleeding time, a decrease of VWF:RCo, FactorVIII:, VWF:Ag, typical VWF multimeric structure and the absence of a family history of bleeding are the basis for the diagnosis of AVWS. Bleeding episodes are typical for AVWS and are mostly of the mucocutaneous type (epistaxis, heavy menstrual bleeding, gingival and postoperative bleedings). Myeloproliferative diseases, particularily essential thrombocythemia, are with 15–18% the third most frequent observed comorbidity of patients with AVWS, but the prevalence of AVWS in patients with MPS is -at our knowledge- still unknown. We investigated 54 patients with the diagnosis of myeloproliferative disease (44 ET, 9 PV, 1 IMF), which was established according to the WHO-criteria over a period of 6 years (2000–2006). By analysing the typical laboratory parameters for AVWS, the VWF multimeric structure and the own and family history of bleeding we detected that 67% (36/45) of these patients had an AVWS: 27/44 ET (61%), 8/9 PV (89%), 1/1 IMF. The two most sensitive parameters in this context were VWF:RC/vWF:Ag- Ratio and VWF:RCo. It is well known that AVWS can disappear by treating the MPD. We could also show that treating the MPD with Hydroxycarbamid platelets, VWF multimeric structure, VWF:RCo/VWF:Ag-Ratio and VWF:RCo and the bleeding tendency were normalized. The JAK2-V617F mutation is frequently found in myeloproliferative disorders (MPD): Up to 97% patients with polycythemia vera (PV) and about 50% of patients with essential thrombocythemia (ET) carry this mutation. A further goal in this investigation was to find out a correlation between JAK2-V617F mutation, MPD and AVWS. JAK2-V617F diagnosis was performed in 27 of the 54 patients with MPD. 10 of these 27 patients carried a mutated JAK2-allele. However we observed no significant difference between mutated and unmutated patients in correlation to AVWS. In our investigation the high prevalence of 67% AVWS in patients with MPD confirm the hypothesis that until now AVWS is an underdiagnosed disease. Because of this high prevalence, the possibility of regression by treating MPD and the importance of early diagnosis for prevention of unexpected, sometimes letal bleeding complications, it would be benefical to introduce the AVWS- diagnosis-procedure as a routine step for patients with MPD.