Introduction: Diagnosis of von Willebrand disease (VWD) is challenging due to heterogeneity of VWD and test limitations. Many von Willebrand factor (VWF) assays are utilized, including antigen (Ag), activity and multimer analysis. Activity assays include ristocetin cofactor using platelets (VWF:RCo) or other particles incorporating recombinant glycoprotein I ('VWF:GPIbR'), or other GPI binding assays using gain-of-function mutations ('VWF:GPIbM'), or collagen binding (VWF:CB).
Aim: To comparatively evaluate modern contemporary VWF activity assays vs VWF multimer analysis using modern contemporary methods.
Materials And Methods: Several VWF activity assays (VWF:RCo, VWF:GPIbR, VWF:GPIbM, VWF:CB) assessed (typically as a ratio against VWF:Ag) against a new semi-automated procedure for different types of VWD (1, 3, 2A, 2B, 2M), plus control material (n = 580). The evaluation also focussed on relative loss of high and very high molecular weight multimers (HMWM and VHMWM) by densitometric scanning.
Results: All evaluated VWF activity/Ag ratios showed high correlation to the presence/absence of HMWM and VHMWM, although VWF:CB/Ag and VWF:GPIbR/Ag ratios using an automated chemiluminescence method yielded highest correlation coefficients (r = .909 and .874, respectively, for HMWM). Use of the investigative procedure (VHMWM) identified fewer false positives for 'loss' in type 1 VWD.
Conclusions: This comparative investigation identified that new automated chemiluminescence VWF activity assays best identified relative loss or presence of HMWM and VHMWM according to activity to Ag ratios and an alternative investigative method for identifying VHMWM in multimer testing for a new commercial multimer method may lead to fewer false identifications of HMW loss in type 1 VWD.
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http://dx.doi.org/10.1111/hae.13957 | 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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