Mild hemophilia A with factor VIII assay discrepancy: using thrombin generation assay to assess the bleeding phenotype

J Thromb Haemost. 2008 Mar;6(3):486-93. doi: 10.1111/j.1538-7836.2007.02861.x. Epub 2007 Nov 28.


Introduction: In some patients with mild hemophilia A, there are discrepancies between 1-stage (1-st) and 2-stage (2-st) factor VIII (FVIII) clotting assays, and also chromogenic assays for FVIII activity (FVIII:C). We examined whether thrombography could provide a better evaluation of the hemostatic status of these patients.

Methods: Two families with such discrepancies and markedly contrasting clinical histories were studied. Family X had no serious bleedings, in contrast to family Y. Sixty-one moderate/mild hemophiliacs without discrepancy and 15 healthy subjects served as controls. Calibrated automated thrombography was performed with platelet-rich plasma after one freeze-thawing cycle and low tissue factor concentration.

Results: The chromogenic FVIII:C levels were higher (0.90 +/- 0.15 and 0.47 +/- 0.13 IU mL(-1)) than the 1-st clotting ones (0.14 +/- 0.05 and 0.10 +/- 0.05 IU mL(-1)) in family X and Y, respectively (P < 0.001). Mean endogenous thrombin potential (ETP) was 1579 +/- 359 nM min(-1) and 1060 +/- 450 for healthy controls and hemophilic controls, respectively. For members of family X, the ETP values were 1188, 1317 and 2277 nM min(-1), whereas for those of family Y they ranged from 447 to 1122 nM min(-1). Two novel missense point mutations were evidenced: p.Ile369Thr in family X and p.Phe2127Ser in family Y. In family X, we postulate that the mutation is responsible for a delayed but non-deleterious FVIII activation.

Conclusions: Our results suggest that the hemostatic phenotype assessed by thrombography may be clinically relevant in moderate/mild hemophilic patients with discrepant FVIII:C results.

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Automation
  • Calibration
  • Case-Control Studies
  • Factor VIII / biosynthesis*
  • Hemophilia A / blood*
  • Hemophilia A / diagnosis*
  • Humans
  • Male
  • Mutation, Missense
  • Pedigree
  • Phenotype
  • Point Mutation
  • Thrombin / metabolism*


  • Factor VIII
  • Thrombin