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Haemophilia A and B

Haemophilia is a hereditary bleeding disorder. There are about 400 people with haemophilia in Finland and a few new cases are diagnosed yearly. Due to the mode of inheritance, haemophilia occurs mainly in men and severe forms of the disease are usually detected in early childhood.

There are two types of haemophilia: type A haemophilia is caused by the deficiency or lack of factor VIII (factor eight, FVIII), while the cause for type B haemophilia is the deficiency or lack of coagulation factor IX (factor nine, FIX). Both type A and B haemophilia manifest in a similar way and can only be distinguished via laboratory tests.

There are more than 3,000 genetic defects known to cause haemophilia. These defects only affect coagulation factor genes and do not cause nor predispose to other diseases. Haemophilia also cannot be transmitted, or emerge later in life in siblings who have been found to be healthy.

Haemophilia can be divided into three severity levels (mild, moderate and severe) based on how the disease manifests and laboratory findings. Haemophilia A is severe in about 50% of cases, while most people with haemophilia B have a moderate or mild bleeding disorder. The coagulation factor deficiency remains the same throughout life. People in the same family with haemophilia have the same gene defect and the same level of disease severity.

Inheritance of haemophilia

The gene defect causing haemophilia is located on the X chromosome, which means the disease is inherited via one of the sex chromosomes. Since women normally have two X chromosomes and men have one X and one Y chromosome, men and boys are always affected by haemophilia whereas women are usually carriers of the disease.

Due to the mode of inheritance, the sons of a man with haemophilia are healthy, and each daughter is a carrier. The sons of a carrier woman have a 50% risk of getting haemophilia and the daughters have a 50% risk of becoming carriers. Families are offered genetic counselling and carriership should be investigated in early adulthood, or at the latest when planning pregnancy. New cases of haemophilia occur both to known haemophilia families and due to new gene defects.

Manifestation of haemophilia

For people with haemophilia, it is typical that bleeding is prolonged and can easily start again. Bleeding is not heavier than what the injury would cause without bleeding disorder, but the bleeding will not stop. In severe haemophilia the bleeding can begin spontaneously, and a minor injury or bleeding can go on for days if left untreated.

In severe haemophilia, bleeding into the joints and muscles is a typical symptom. Without efficacious and regular coagulation factor replacement therapy, or other medical therapy, recurrent bleeding into the joints leads to permanent function-impairing arthritis and causes the surrounding muscles to atrophy, reducing function. The typical first symptoms are sensations such as tingling and warmness of the joint, as well as reduced movement. As the bleeding continues it causes swelling and pain. Muscle bleeds cause pain, reduced movement, numbness and, as an after-effect, muscle atrophy. Profuse bleeding can cause pressure in the tissues surrounding the muscle, prevent blood circulation and cause nerve compression, which can lead to circulatory disorders, numbness and paralysis symptoms.

Scratches, superficial wounds and pinpricks on the skin normally stop bleeding if pressure is applied to the location of the injury. This is because in the early stages of coagulation, platelets (i.e. thrombocytes) quickly form a plug at the damaged site that stops the bleeding. Bruises and minor soft tissue bleeds are also usually limited and heal on their own. In mucosal areas, such as in nose bleeds, platelets are important for coagulation in addition to coagulation factors. Oral mucosal ulcers can ooze for a long time without treatment, since the vasculature is abundant and the movement and mechanical irritation caused by talking, eating and drinking constantly interferes with wound healing.

More info on the manifestation of haemophilia can be found in our guide.

Treatment of haemophilia

Preventive, i.e. prophylactic, coagulation factor replacement therapy, or other medical therapy, decreases the impact of severe haemophilia into the equivalent of moderate or mild haemophilia and reduces bleeding tendency. In children, preventive treatment is especially important in order to avoid joint and muscle bleeding affecting growth during the sensitive development phase of the skeletal system.

Recurrent bleeding damages tissue more the more often it occurs and the longer it continues. Therefore, stopping the bleeding quickly is of utmost importance. When bleeding or a situation causing it occurs, such as a sprain or strain injury due to a crash, coagulation factor replacement therapy must be started immediately. An injury requires coagulation factor treatment to be initiated even if there were no signs of bleeding yet. The dosage should be higher than in regular preventive treatment and the treatment should last a few days depending on the response.

Replacement therapy is carried out by administering the missing coagulation factor preparation intravenously. With small children, a subcutaneous venous port is often used. Parents, or trained persons treating the child, are then able to administer the coagulation factor preparation until replacement therapy can be implemented independently at school age. Adults primarily administer their own medication.

New treatment methods discovered through basic research of blood coagulation bring significant relief to the everyday life of people with haemophilia. Nowadays, a treatment for type A haemophilia is available which can be administered subcutaneously every week, every two weeks or every four weeks. In addition, there have been remarkable developments in gene therapy for the treatment of haemophilia. In this type of therapy, the gene for coagulation factor IX or VIII is transferred to the liver with the help of a gene carrier, i.e. vector, via a single intravenous infusion, after which liver cells start producing the missing coagulation factor.

It is recommended that the treatment and regular monitoring of bleeding disorders be conducted in treatment centres specialised in coagulation disorders, in which treatment may be coordinated in a multidisciplinary manner. A central part of the current treatment of haemophilia is the personalisation of coagulation factor replacement therapy based on treatment response, and at-home monitoring, for example with mobile applications.

More information on the treatment of haemophilia and the subcutaneous venous port for children can be found in our guide.

Duodecim Terveyskirjasto and the Verenvuotaudit — Tietopaketti potilaille guide have been used as text references.