Development of an FVIII Inhibitor in a Mild Hemophilia Patient with a Phe595Cys Mutation

: Mild hemophilia A is caused by a missense mutation in the FVIII gene that is responsible for a decrease in the FVIII:C to between 5% and 40%. The development of FVIII inhibitors has been reported in 3-13% of patients with mild hemophilia. Genetic risk factors for the development of inhibitors in mild hemophilia have been investigated. In the present study, we encountered a case of mild hemophilia with an FVIII inhibitor and identified the mutation responsible: a novel Phe595Cys mutation in the FVIII gene. In addition, this study showed that the inhibitor recognized exogenous wild-type FVIII and autologous mutant FVIII.