What is Hemophilia A or B?

The most important information about the causes, inheritance and therapy of hemophilia, formerly known as "hemophilia"

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Hemophilia - Briefly Explained

Hemophilia A and B are hereditary diseases in which blood clotting is impaired due to a lack of clotting factors. In hemophilia A, factor VIII is absent, in hemophilia B, factor IX. Those affected can bleed spontaneously or after injuries and accidents, but also during interventions or spontaneous. Since the altered genes responsible for haemophilia are on the X chromosome and are inherited recessively, boys in particular get the disease. Treatment usually consists of administering the missing coagulation factors - either regularly as a preventative measure or when necessary.

Haemophilia, formerly also called "hemophilia", is a hereditary disease. It mainly affects boys and men. In the case of haemophilia, blood clotting is impaired. As a result, the blood from a wound does not coagulate or coagulates only slowly, and spontaneous bleeding can also occur. People with haemophilia now have a normal life expectancy thanks to good treatment.

What are the causes of hemophilia?

The interplay of various coagulation factors is a prerequisite for normal blood coagulation. The human blood coagulation system has 13 factors, which are designated with the Roman numerals I to XIII. The causes are different in hemophilia A and B:

  • Haemophilia A: Haemophilia A has an inherited deficiency or reduced activity of coagulation factor VIII (factor eight).
  • Haemophilia B: If there is no coagulation factor IX (factor nine) or if its activity is reduced, it is haemophilia B.

In addition to these two common forms, there are other, much rarer types of hemophilia.

Inheritance: how does hemophilia develop?

Hemophilia A and B are inherited as an X-linked recessive trait. This means: The genetic make-up for hemophilia A and B lies on the X chromosome and is passed on with it. Women have two X-chromosomes: one they inherit from their mother and one from their father. Men, on the other hand, only have one X-chromosome, which they inherit from their mother. Men inherit the Y-chromosome from their father.

If boys inherit an X chromosome from their mother with an appropriately modified gene for factors VIII or IX, they develop hemophilia.

Women can also carry the gene change on the X chromosome. However, if they have a second, "healthy" X chromosome - which is usually the case - they will not become ill. However, they can pass on the X chromosome with the defect and thus the disease to their children. Such women are therefore referred to as "transmitters". Sometimes they also have a slightly increased tendency to bleed.

If a woman has inherited the gene change on the X chromosome from both her mother and her father, she will have two changed X chromosomes and will develop hemophilia. However, this is rare.

The incidence of hemophilia in newborn boys is approximately 1 in 5000; Hemophilia A is more common than hemophilia B. In Germany, around 10,000 men live with hemophilia.

Which symptoms are typical?

The bleeding tendency is the same in both forms of hemophilia. It is usually noticed in childhood, especially since the hereditary disease is often known in affected families:

  • Those affected get extensive bruises (hematomas) particularly easily.
  • Painful bleeding in the joints is typical. They can cause joint damage and - without suitable therapy - lead to premature osteoarthritis and joint stiffening.
  • Bleeding is difficult to stop after injuries.
  • Affected women may have prolonged or increased menstrual bleeding.
  • Extensive muscle bleeding after a shock or an accident is also feared. Heavy muscle bleeding also occurs after injections into the muscle (intramuscular injections).
  • There is a danger to life if there is bleeding from internal organs or in the head. If left untreated, bleeding can sometimes be fatal.
  • It is also characteristic that bleeding initially stops, but can start again as late bleeding after hours or days.

What are the severity grades of hemophilia?

The severity of the hemophilia is defined by the measured residual activity of the respective coagulation factor in the body.

  • Severe haemophilia: The activity of the coagulation factor is less than one percent.
  • Moderate haemophilia: Here the activity of the coagulation factor is between one and five percent.
  • Mild or mild haemophilia: The activity of the coagulation factor is between five and 40 percent. Bleeding usually only occurs after an accident or injury.

How does the doctor make a diagnosis?

The diagnosis is based on the typical symptoms, often also family history. Blood tests, especially coagulation tests, provide additional information.

What does the therapy look like?

A cure for the hemophilia is not yet possible. However, those affected can lead a largely normal life today if the missing or defective coagulation factor is replaced. This can either only happen when necessary, for example in the event of an injury or an upcoming operation, or it can be a preventative measure. For more severe forms of haemophilia, treatment is usually preventative. The affected persons usually inject the corresponding factor concentrate into their veins themselves every few days.

One possible complication, however, is that patients with haemophilia A develop their own defense substances (antibodies) against factor VIII. This weakens the effect of the supplied factor VIII. Such antibodies against the supplied coagulation factor can also occur in haemophilia B.

In mild forms of haemophilia, preparations such as the hormone desmopressin are sometimes used, which increase the release of coagulation factors. An antibody called emicizumab for the treatment of haemophilia A has also been approved since 2018. It works as factor VIII normally does and is not inactivated by antibodies directed against factor VIII. It can be injected under the skin as a preventive measure; it is only necessary to administer it once a week.

Exercise for hemophilia?

Sports used to be viewed very critically because of the risk of injury. But sport also has positive effects. It can even help reduce the risk of injury in everyday life by training flexibility and coordination. After consulting the attending physician and using appropriate protective equipment and, if necessary, a helmet, hemophilia patients can often practice the desired sport. However, among other things, the following are considered unsuitable or unsuitable:

  • Soccer
  • Hockey and ice hockey
  • Martial arts, boxing
  • Weightlifting

Consulting expert

Professor Dr. med. Wolfram Delius is a specialist in internal medicine and cardiology. He completed his habilitation at the Medical University Clinic Uppsala, Sweden, and then held an extraordinary professorship for medicine at the Technical University of Munich. The heart specialist worked for a long time as chief physician, most recently for two decades in the cardiology / pulmonology department at the Munich-Bogenhausen Municipal Hospital (academic teaching hospital).He now runs his own practice.

Professor Delius has been actively involved in advanced training events of the Bavarian Medical Association for years and was awarded the Ernst von Bergmann plaque of the German Medical Association.

Important NOTE:
This article contains general information only and should not be used for self-diagnosis or self-treatment. He can not substitute a visit at the doctor. Unfortunately, our experts cannot answer individual questions.

Further sources:

Hoots WK, Shapiro AD. Hemophilia A and B: Routine management including prophylaxis. ed. UpToDate Walthma MA: UpToDAte Inc. https://www.uptodate.com (accessed on July 17, 2019)

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