Discrepancy in factor VIII 1-stage/2-stage activity in a child with Arg(531)--> His mutation

Blood Coagul Fibrinolysis. 2010 Jul;21(5):474-5. doi: 10.1097/mbc.0b013e328338db53.


Routine screening of infants born to known hemophilia carriers includes a factor VIII (FVIII) level. In routine practice, mild FVIII deficiency variants may be missed by laboratories that exclusively use a one-stage activated partial thromboplastin time-based activity assay. This case illustrates such a possibility with a discrepancy between the one-stage and two-stage assays performed on a child who carries the Arg(531) --> His mutation.

Publication types

  • Case Reports

MeSH terms

  • Amino Acid Substitution / genetics
  • Arginine / genetics*
  • Child
  • Factor VIII / genetics*
  • Hemophilia A / diagnosis
  • Hemophilia A / genetics*
  • Histidine / genetics*
  • Humans
  • Male
  • Mutation, Missense / genetics*


  • Histidine
  • Factor VIII
  • Arginine