RESUMEN
BACKGROUND AND OBJECTIVES: von Willebrand's disease (vWD) is a bleeding disorder with variable clinical expression. Our aim was to classify patients with vWD and to determine the phenotype in their relatives. DESIGN AND METHODS: The types and subtypes, blood group frequency and its relevance, bleeding sites, response to the desmopressin (DDAVP) test, transfusion requirements and clinical features in type 1 and 2A families were determined in 1,885 patients. RESULTS: Our findings were: type 1: 91%, type 2A: 3.1%, severe vWD: 1.3%; type 2N: 1.6%; type low intraplatelet: 2.7%; combined 1+ 2N: 0.3%. Blood group O prevalence was 70.5%. Bleeding and transfusion requirements were not correlated to blood groups. The most frequent symptoms were: ecchymoses-hematomas and epistaxis and, in females over 13 years, also menorrhagia. Normal levels of factor VIII:C were found in 38.4% of the patients. DDAVP was infused in 567 patients with a good response in 80.6%. About 9% of our patients needed transfusion therapy. The diagnosis of von Willebrand's disease is more likely in subjects belonging to families with type 2A disease than in members of families with type 1 vWD in spite of these being symptomatic. INTERPRETATION AND CONCLUSIONS: These observations provide a good strategy to identify, classify and treat vWD patients without performing molecular assays.