Haemophilia is a hereditary bleeding disorder affecting approximately 1 in every 10,000 people1. People with haemophilia have either decreased, defective or absent production of blood clotting proteins. Bleeds often occur in the joints, particularly knees and ankles but they can also occur in the muscles, soft tissues, gastrointestinal tract and even the brain.
Trauma, major surgery, tooth extractions or other minor surgical operations require medical intervention to manage the associated bleeding. Without treatment bleeds are painful, can cause lasting damages and lead to impaired mobility.
There are two types of haemophilia: haemophilia A and haemophilia B. People with haemophilia A have issues with the production of the blood clotting factor VIII. Those with haemophilia B have similar deficiencies with clotting factor IX.
Haemophilia is characterised as “severe” when the activity of the affected clotting factor is less than 1% of normal. Severe Haemophilia is often associated with spontaneous bleeding, not caused by injury. Haemophilia is moderate when clotting factor activity is between 1% and 5% of normal and “mild” when the relevant clotting factor activity is greater than 5%, but less than normal.
An estimated 400,000 men have haemophilia A or B but only 25% of them have a confirmed diagnosis and access to adequate care, according to the World Federation of Hemophilia2. Around 80% of people with haemophilia and allied bleeding disorders live in the developing world and approximately 50% have severe haemophilia which typically requires treatment several times per month.
Acquired haemophilia is a spontaneous development of inhibitors which affect a person’s FVIII clotting factor. Acquired haemophilia affects about one in one million people. The underlying cause of inhibitor development is usually unknown but may occur in relation to pregnancy, autoimmune disease, the use of certain medications or cancer. Patients with acquired haemophilia may initially go to the hospital as a result of a severe spontaneous bleeding episode which will not typically respond to treatment with FVIII.
Haemophilia A and B can be treated by substituting the missing clotting factor by intravenous injection, either when bleeding occurs or through a planned course of treatment. The replacement clotting factors have typically been obtained from human plasma or from recombinant technology in a laboratory.
One of the most feared complications in the treatment of haemophilia is the development of ‘inhibitors’. Inhibitors are antibodies to FVIII or FIX that can develop in people with haemophilia following replacement therapy for the missing coagulation factor.
Treatment-complicating inhibitors affect about 30% of people with haemophilia A and 4% of people with haemophilia B. Most of these inhibitors develop during childhood and are detected when patients fail to respond to standard replacement therapy. Inhibitor levels are measured in Bethesda units (BU).
von Willebrand Disease
Von Willebrand Disease (vWD) is another bleeding disorder. Although more common than haemophilia, vWD is normally less serious. vWD is most often caused by genetic mutations that either impair a person’s ability to make von Willebrand factor or lead to the production of defective forms of the protein. Most people with the condition display very mild symptoms. The first clues often come when bleeding will not stop during surgery or after a serious injury. Women with vWD tend to have more symptoms than men because of menstruation and childbirth.
Allied Rare Bleeding Disorders
Haemophilia A, haemophilia B and von Willebrand Disease represent around 96% of inherited bleeding disorders. Deficiencies in the remaining coagulation factors such as fibrinogen, factor II, V,V+VIII, VII, X, XI and XIII are classified as Rare Bleeding Disorders (RBDs). They affect one in every 500k – 2m people. Both men and women can be affected by RBDs because the deficiency is not linked to the X chromosome. The most commonly reported symptoms are bleeding from the nose, mouth and gums, presence of blood in urine, bruises, and bleeding during or after surgery.
1 Source: https://www.wfh.org/en/page.aspx?pid=646
2 Source: https://www.wfh.org/en/about-us