Background: Diagnosis of von Willebrand disease (VWD) type 2 usually relies on the discrepancy between the von Willebrand factor (VWF) ristocetin cofactor activity (VWF:RCo) and VWF antigen (VWF:Ag). Type 2B patients can be discriminated from other qualitative VWD variants by using ristocetin-induced platelet agglutination (RIPA) test. The major limitation of RIPA is the requirement of fresh blood sample.
Objectives: In this study, we evaluated the VWF gain-of-function mutant GPIb binding (VWF:GPIbM) and VWF:RCo assays to investigate whether the VWF:GPIbM/VWF:RCo ratio was able to identify the type 2B variant among an heterogeneous VWD population, previously characterized following the ISTH-SSC guidelines.
Patients/methods: Seventy-six VWD patients and 31 healthy subjects were evaluated by using VWF:Ag, VWF:RCo, and VWF:GPIbM assays.
Results: The mean (minimum-maximum values) VWF:GPIbM/VWF:RCo ratio was higher in type 2B patients (2.53, 0.84-6.11) than in healthy controls (1.05, 0.87-1.34), type 1 (0.85, 0.51-1.15), 2A (1.20, 0.36-2.82), and 2M (1.07, 0.91-1.38) (P < 0.0001). Type 2B variants were divided into four groups (A, B, C, and D) according to their different multimeric patterns. The mean value of the VWF:GPIbM/VWF:RCo ratio in the four groups showed an increasing trend from group A (1.08) to D (3.69), proportional to the loss of high molecular weight multimers. Among 32 type 2B patients, previously diagnosed with RIPA, 8 (mainly with a type I New York/Malmö phenotype) were not confirmed using the VWF:GPIbM/VWF:RCo ratio.
Conclusions: Whenever the RIPA test is not feasible, the VWF:GPIbM/VWF:RCo ratio might help to identify severe type 2B VWD patients.
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http://dx.doi.org/10.1111/jth.13062 | DOI Listing |
Virchows Arch
December 2021
Department of Plastic Surgery, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.
Merkel cell carcinoma (MCC) is a rare and aggressive neuroendocrine malignancy of the skin. The cell of origin of MCC is thus far unknown and proposed cells of origin include Merkel cells, pro-/pre- or pre-B cells, epithelial stem cells, and dermal stem cells. In this study, we aimed to shed further light on the possibility that a subset of MCC tumors arise from epithelial stem cells of the skin by examining the expression of hair follicle and epidermal stem cell markers in MCC and normal human skin.
View Article and Find Full Text PDFAm J Med Genet A
June 2021
The Folkhaelsan Department of Medical Genetics, The Folkhaelsan Institute of Genetics and the Department of Medical and Clinical Genetics, Medicum, University of Helsinki, Helsinki, Finland.
J Transl Med
October 2020
Institute of Neurophysiology, Medical Faculty Mannheim, University Heidelberg, Heidelberg, Germany.
J Eur Acad Dermatol Venereol
February 2019
Department of Dermatology, Allergology and Venereology, Helsinki University Central Hospital, Helsinki, Finland.
Transplantation
January 2016
1 Transplantation Laboratory, University of Helsinki, Helsinki, Finland. 2 Department of surgery, Oulu University Central Hospital, Oulu, Finland. 3 Transplantation and Liver Surgery Unit, Helsinki University Central Hospital, Helsinki, Finland. 4 Division of Nephrology, Department of Medicine, Helsinki University Central Hospital, Helsinki, Finland.
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