It is an X-linked disease, where an infected individual will continue to bleed even from a minor cut since the patient does not possess the natural phenomenon of blood clotting.
It is mainly due to the absence of antihemophilic globulin or factor VIII (hemophilia – A) and plasma thromboplastin factor IX.
It is called the Christmas disease as it is named after the first patient Stephen Christmas who was diagnosed with the disease in 1952.