Understanding the pathogenesis of haemophilia A has allowed for detailed diagnosis of the condition at molecular level. Evaluation of interaction between factor VIII and von Willebrand factor has been utilised to distinguish mild forms of haemophilia A from von Willebrand disease. Discovery of wide spectrum of mutations in the factor VIII gene and their association with different severity of the disease allowed for development of a rational strategy for mutation detection in clinical settings. Characterisation of the genetic defects is required for carrier detection and antenatal testing and it also helps to predict risk of factor VIII inhibitor development. Research is ongoing to establish less invasive prenatal testing and to move the testing to pre-gravid period.

        Key words: haemophilia A, von Willebrand factor, factor VIII, mutation, polymorfism, factor VIII inhibitor, prenatal diagnosis, preimlantation diagnosis.