Von Willebrand Factor antigen and age explain variation in baseline FVIII:C among nonsevere hemophilia A patients with the same F8 genotype (Arg593Cys and Asn618Ser)

Janneke I. Loomans, Alice S. Van Velzen, Corien L. Eckhardt, Marjolein Peters, Jan Astermark, Paul P. Brons, Giancarlo Castaman, Marjon H. Cnossen, Natasja Dors, Carmen Escuriolaettingshausen, Karly Hamulyak, Daniel P. Hart, Charles R.M. Hay, Saturnino Haya, Waander L. Van Heerde, Cedric Hermans, Margaretha Holmström, Victor J. Imenez-Yuste, Russell D. Keenan, Robert KlamrothChristoph Königs, Marieke J.H.A. Kruip, Britta A.P. Laros-Van Gorkom, Frank W. G. Leebeek, Ri Liesner, Anne Mäkipernaa, Christoph Male, Evelien Mauser-Bunschoten, Maria G. Mazzucconi, Simon Mcrae, Karina Meijer, Michael Mitchell, Massimo Morfini, Marten Nijziel, Johannes Oldenburg, Kathelijne Peerlinck, Pia Petrini, Helen Platokouki, Savita Rangarajan, Sylvia E. Reitter-Pfoertner, Elena Santagostino, Piercarla Schinco, Frans J. Smiers, Berthold Siegmund, Annarita Tagliaferri, Thynn T. Yee, Pieter Willem Kamphuisen, Johanna G. Van Der Bom, Karin Fijnvandraat

Research output: Contribution to journalMeeting AbstractAcademic

Abstract

Introduction and Objectives: Non-severe hemophilia A (baseline FVIII:C, 2-40 IU/dL) is caused by a mutation in the F8 gene. There is limited knowledge on the factors determining the variation in baseline FVIII:C. The aim is to identify the determinants of baseline FVIII:C in non-severe hemophilia A patients. Materials and Methods: We analyzed clinical data for non-severe hemophilia A patients, treated between 1980-2013, in European Haemophilia Treatment Centers (HTCs) participating in the INSIGHT/RISE project. We performed analyses on mutations that were present in ≥10 patients. Age (at FVIII:C measurement), F8 gene mutation, VWF:Ag, VWF:Act and HTC were analyzed as potential determinants by multivariate regression analyses. Results: We identified nine missense mutations present in ≥10 patients in 321 individuals, median age 23 years (IQR 7-47). From these individuals we had data on 667 FVIII:C measurements in 5 HTCs. Median baseline FVIII:C, VWF:Ag and VWF: Act were 17 IU/dL (IQR 11-22), 98 IU/dL (IQR 78-128) and 91 IU/dL (70-115) respectively. Baseline FVIII:C, VWF:Ag and VWF:Act all increased with age, both in the total population and within the two largest mutation groups (Asn618Ser, 113 patients; Arg593Cys, 107 patients). VWF:Ag, age and F8 mutation were significant predictors of baseline FVIII:C (p <0.0001-0.024). In mutations that were present in ≥10 patients the determinants age, F8 mutation, VWF:Ag and HTC together explained 61% of the variation in baseline FVIII:C. Within the specific mutation group Asn618Ser only 21% of the variance in baseline FVIII:C was explained by the combined potential determinants, with VWF:Ag and HTC as significant predictors (p = 0.008 and 0.013 respectively). Among individuals with the Arg593Cys F8 genotype the determinants age, VWF:Ag and HTC were significant predictors (p <0.0001 for age and VWF:Ag and p = 0.04 for HTC), together explaining 34% of the variance in baseline FVIII:C. Conclusion: In non-severe hemophilia A patients carrying the same F8 mutation the determinants age, VWF:Ag and HTC contribute to baseline FVIII:C to variable extends. With the studied determinants we can only explain 61% of the variance in baseline FVIII:C. This suggests that yet unknown factors influence FVIII:C in nonsevere hemophilia A.
Original languageEnglish
Pages (from-to)56
Number of pages1
JournalHaemophilia
Volume20
Publication statusPublished - 1-May-2014

Keywords

  • von Willebrand factor
  • antigen
  • silver
  • hemophilia A
  • patient
  • human
  • genotype
  • hemophilia
  • mutation
  • missense mutation
  • regression analysis
  • gene mutation
  • population
  • clinical study
  • gene

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