Laboratory diagnosis and management of von Willebrand disease in South Africa

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Date
2011
Authors
Meiring, Muriel
Coetzee, Marius
Kelderman, Mareli
Badenhorst, Philip
Journal Title
Journal ISSN
Volume Title
Publisher
Thieme Medical Publishers
Abstract
Patients with von Willebrand disease (VWD) in South Africa are cared for in 17 Hemophilia Treatment Centers. The exact prevalence of the disease is uncertain, but 539 patients are annotated in registries. VWD patients are mostly diagnosed in the five largest academic centers, and the classification of the subtypes is performed by one of these, the VWD testing facility. An algorithm is used for the diagnosis of VWD. The distribution of subtypes diagnosed by the VWD reference center is 38%, 58%, and 4% for type 1, 2, and 3, respectively, and ~15% of plasma samples received are rejected due to poor storage and transport conditions. A novel single nucleotide polymorphism has been found in an African patient with type 2B VWD. From the type 1 VWDpatients who were diagnosed by the VWD testing facility, 45% seem to have an increased VWF clearance phenotype with a propeptide-to-antigen ratio of 1.9±0.3. VWD patients are treated with desmopressin, factor (F)VIII/VWF concentrate (Haemosolvate FVIII; National Bioproducts Institute, Durban, South Africa), and tranexamic acid. Haemosolvate FVIII contains a VWF antigen concentration of 167±27 IU/mL, a ristocetin cofactor activity of 100±29 IU/mL, a collagen binding activity of 99±29 IU/mL, normal VWF multimers, and a FVIII concentration of 50 IU/mL. Not all patients with VWD are currently classified, and many VWD patients in South Africa are probably undiagnosed.
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Keywords
Von Willebrand disease, Classification, Diagnosis, Hemophilia treatment centers, South Africa, Diagnosis, Laboratory, Blood -- Diseases, Hemophilia
Citation
Badenhorst, P. (2011). Laboratory diagnosis and management of von Willebrand disease in South Africa. Semin Thromb Hemost, 37, 576-580.