Abstract

Haemophilia A is caused by faulty synthesis of Factor VIII of the coagulation cascade. Haemophilia B (Christmas disease) is caused by a deficiency of Factor IX. The two conditions are clinically similar; all patients suffer from prolonged bleeding after trauma and in the more severely affected there is also spontaneous haemorrhage, particularly into joints and muscles. Correction of factor deficiency by plasma concentrates restores haemostasis but the intermittent nature of the haemorrhage, the scarcity of the transfused coagulation factors and their short plasma half-lives in most cases limit treatment to episodes of bleeding.