Molecular genetics of hemophilia A: Clinical perspectives

Since the publication of the sequence of the factor VIII (F8) gene in 1984, a large number of mutations that cause hemophilia A have been identified and a significant progress has been made in translating this knowledge for clinical diagnostic and therapeutic purposes. Molecular genetic testing is used to determine the carrier status, for prenatal diagnosis, for prediction of the likelihood of inhibitor development, and even can be possibly used to predict responsiveness to immune tolerance induction. Phenotypic heterogeneity of hemophilia is multifactorial, mainly related to F8 mutation but other factors contribute especially to coinheritance of prothrombotic genes. Inhibitor development is mainly related to F8 null mutations, but other genetic and non genetic factors could contribute. This review will focus on the genetic aspects of hemophilia A and their application in the clinical setting and the care of patients and their families.