Classification of von Willebrand disease in Maltese patients

Abstract

Von Willebrand factor (vWF) plays a key role in platelet adhesion, thrombus formation and coagulation, the latter as carrier protein for factor VIII(F VIII). VWF deficiencies lead to von Willebrand Disease(vWD), the most common congenital bleeding disorder. Approximately 125 individuals per million population have symptomatic vWD, and this is roughly twice the prevalence of hemophilia A. Asymptomatic inherited defects in von Willebrand factor(VWF) function are extremely common and are detectable in nearly 1 % of unselected persons. In a survey of European patients, the prevalence of treated vWD varied from 4.5 to 24 per million. Preliminary results of an international survey of vWD indicate that about 3% of treated patients have seroconversion to human immunodeficiency virus, 50% of whom have symptoms. Recent progress in the characterization of mutations that cause vWD has provided the necessary stimulus to re-address the issue of how vWD is classified. In response to this situation, in July 1993, the subcommitee on vWF of the Scientific and Standardization Committee of the International Society on Thrombosis and Haemostasis proposed a simplified phenotypic classification of van Willebrand disease based on differences in pathophysiology. The revised classification basically distinguishes partial quantitative (type 1), qualitative (type 2) and total quantitative (type 3) deficiency of vWF. A goal for the new classification is to maximize the correlation of subtypes with treatment choices as it depends on the accurate diagnosis and classification of vWD in the patient. Specific aims: Tu try to identify all Maltese patients suffering from von Willebrand Disease by inviting all family members of all known cases of vWD patients to participate in the study. To perform two new assays which were never performed locally to help in the routine assay panel used to classifying Maltese patients in the recent revised classification. This is important as there are many treatment choices depending on the accurate diagnosis and classification of vWD in the patient for a successful patient management. Finally, genetic counselling for all the extended family for a better understanding of their bleeding condition.