What is hemophilia?

Hemophilia is a congenital bleeding disorder. Its prevalence is estimated to be 30 to 40 per million inhabitants.

Patients with Hemophilia A have absent, decreased or defective production of the important blood clotting protein, Factor VIII. Those with hemophilia B have similar problems with Factor IX blood clotting protein.

Hemophilia is characterised as "severe" when the activity of the affected clotting factor is less than 1% of normal. As a result, patients with severe hemophilia will sometimes even bleed spontaneously. The disease is termed "mild" when activity is greater than 5% of normal and "moderate" when clotting factor activity is between these two values. Approximately 50% of hemophilia patients have moderate or severe disease and can require treatment for severe hemorrhages several times per month or a few times a year.

Severe hemophilia becomes apparent in the first years of life. As soon as a child starts to move about independently, hemorrhages can occur into the joints (particularly the weight bearing joints such as knees, ankles and hips). These bleeds can cause severe pain and even permanent joint damage, with the risk of severe deformity and disability. Life or limb threatening bleeding may also occur into the muscles and soft tissues, and severe gastrointestinal bleeding and intra-abdominal hemorrhages occasionally arise. Cerebral hemorrhages are a constant risk. Superficial trauma, tooth extractions/other minor surgical interventions and major surgery can give rise to uncontrollable bleeding.

Hemophilia A

Hemophilia A is an X-linked recessive condition only confined to males. The disease may be passed on through their daughters. The daughter of a man with hemophilia will always be a carrier of hemophilia. Her sons will have a 50% risk of suffering from hemophilia and her daughters will have a 50% risk of being a carrier.

Hemophilia B

Haemophilia B is inherited in the same way as Hemophilia A, but it is five times less common. Clinical impact is similar to Hemophilia A and it can only be differentiated from Hemophilia A through a blood test. It is sometimes called Christmas disease after a Mr. Christmas, the first patient in whom it was recognized.

Hemophilia patients with inhibitors

'Inhibitors is the term used to refer to the neutralising antibodies that can develop in patients with hemophilia (A or B). The incidence of the development of inhibitors is approximately 10 to 30% in hemophilia A and 3 to 5% in Hemophilia B patients. Patients that develop inhibitors usually develop them before the age of 20. The management of hemophilia patients with inhibitors has the potential to be quite difficult. Clinically, most inhibitors are detected or recognised when patients fail to respond to standard replacement therapy. The antibodies are quantified with an assay that measures the inhibitor level in Bethesda units (BU).

Acquired Hemophilia

Acquired hemophilia can be described as a spontaneous development of inhibitors to factor VIII or IX in a patient that was otherwise normal (i.e., not born with hemophilia). The underlying cause of inhibitor development may be idiopathic (unknown) or potentially due to pregnancy, aging, autoimmune disease or cancer. Patients with acquired hemophilia may often present as an emergency case with life-threatening spontaneous bleeding episodes that are very difficult to control, even with infusions of large amounts of replacement clotting factors.


	congenital Referring to conditions that are present at birth. hemorrhages a bleed cerebral hemorrhages a bleed that occurs in the brain X-linked recessive condition a condition or disease that is related to a defect on the X chromosome (i.e. the chromosome passed on by the mother) and which expresses itself in 50% of related male children inhibitors a protein or antibody that can attack and neutralize specific blood clotting factors (usually Factor VIII or Factor IX) Bethesda Unit a unit of measure used to describe the ability of a patient's inhibitors to neutralize specific blood clotting factors (one Bethesda Unit is defined as the level of inhibitor that is able to neutralize 50% of a patient's Factor VIII or IX activity in 2 hours at 37oC)