Clotting factors VIII and IX

Abstract

Haemophilia is the most common congenital disorder of coagulation and affects approximately 1 in 10,000 males around the world. Haemophilia A is due to a deficiency of factor VIII in the circulating blood whilst haemophilia B (also known as Christmas disease) is a clinically identical disorder caused by factor IX deficiency. It is less common than haemophilia A and affects 1 in about 30,000 males. Both factors VIII and IX are essential glycoproteins in the clotting cascade [1] (Fig. 1). The hallmark of severe haemophilia is recurrent and spontaneous haemarthrosis, typically affecting the hinge joints such as the ankle, knee and elbow. The severity of bleeding depends upon the level of factor in the blood.