What is haemophilia

Haemophilia is a genetic disorder of haemostasis, that is, the blood clotting process. It is due to the lack or deficiency of a blood protein called clotting factor. In the blood plasma there are several factors (13 in total), which are called coagulation factors I-XIII and are all necessary for the haemostatic process. When one of these coagulation factors is absent or in low levels, the blood does not clot quickly, resulting in the person bleeding for longer time than other people do.

Haemophilia occurs more frequently in males than females, as is genetically transferred from mother to son. Therefore, the person is born with the disorder and lives with it throughout his or her life. The chance of giving birth to a girl with haemophilia is very rare.

The blood clotting process

When blood vessel brakes, specific blood cells, called platelets, concentrate at that point and create a clot, The clotting factors then form a matrix surrounding the clot, which stabilizes it at the point of bleeding. This way, the point of blood leakage is “sealed” and the bleeding stops.

In case of haemophilia, the absence or insufficient amount of one of the clotting factors prevents the formation of a strong matrix around the clot, making the clot easily degradable and the bleeding to continue for longer period.

There are two major types of haemophilia:

Haemophilia A

In haemophilia A there is lack or deficiency of clotting factor VIII (Factor 8). It is the most common type of haemophilia as it accounts for about 80% of haemophilia cases. Haemophilia A occurs in 1 in 5,000 newborn boys or in 1 in 10,000 births.

Haemophilia B

Haemophilia B (also known as Christmas disease) is caused by the lack or deficiency of clotting factor IX (factor 9).

Haemophilia C, which is extremely rare, is caused by the lack or deficiency of clotting factor XI (factor 11). It affects both men and women.

A bleeding may be caused either by injury or surgery, or without obvious cause (spontaneous bleeding). Spontaneous bleedings usually occur in the muscles and joints, as well as in internal organs. If not immediately perceived and not addressed as soon as possible, they can be life-threatening (especially intracranial bleeding).

Depending on the levels of clotting factor in the blood, haemophilia is classified as mild, moderate and severe.

Mild

In mild haemophilia, factor levels range between 6% – 40%. A generally experience bleeding only after serious injury, trauma or surgery. In many cases, mild hemophilia is not diagnosed until an injury, surgery or tooth extraction results in prolonged bleeding. The first episode may not occur until adulthood. Women with mild hemophilia often experience menorrhagia, heavy menstrual periods, and can hemorrhage after childbirth.

Moderate

In moderate haemophilia, the factor is found in the blood, at levels between 1% to 5%. People with moderate hemophilia A tend to have bleeding episodes after injuries. Bleeds that occur without obvious cause are called spontaneous bleed ingepisodes.

Severe

In severe haemophilia, the factor is completely absent or present in less than 1%. People with severe hemophilia A experience bleeding following an injury and may have frequent spontaneous bleeding episodes, often into their joints and muscles.

Haemophilia is diagnosed by blood tests that measure platelet count, blood clotting time, prothrombin time (PT) and partial thromboplastin time (aPTT), followed by measurements of factor VIII or factor IX levels.

The diagnosis of mild or severe haemophilia is usually made in infancy (0-2 years old), as the baby’s parents observe bruises on their hands or feet, especially when they start crawling or walking.

Haemophilia should not be confused with von Willebrand disease, a bleeding disorder due to the lack or defective function of a different type of clotting factor, called von Willebrand factor (VWF).