• 10-12-2021

Hemophilia is usually an inherited condition in which blood does not clot properly.

Blood circulates throughout the body through veins, arteries, and capillaries. When cut, the skin is injured, as well as the capillaries, from which blood begins to flow. To stop bleeding, the capillary narrows, and special blood cells – platelets – form a plug to patch the hole. Plasma (the liquid part of the blood) contains many clotting factors that help platelets to make a plug and stop bleeding.

In hemophilia, there is no or too little blood clotting factor. Because of this, the clot, which is supposed to stop the blood, does not form properly and the bleeding continues for a longer time than usual.

Plasma contains many clotting factors. Each factor is numbered with a Roman numeral. The two most common factors affecting blood clotting are factor VIII (8) and factor IX (9).

Types of hemophilia

There are several types of hemophilia, but two of them are the most common:

Hemophilia A. The blood lacks clotting factor VIII. Approximately 85% of all hemophiliacs.

Hemophilia B. The blood lacks clotting factor IX.

Hemophilia is also classified according to its severity. It can be mild, moderate, or severe, depending on the level of the clotting factor.

Symptoms of hemophilia

Symptoms of hemophilia vary depending on the severity of the disorder. In most cases, symptoms appear during childhood. But sometimes, with a mild hemophilia, the disease can be detected in adulthood.

The most common symptoms of hemophilia are:

  • Blood in urine or stool.
  • Frequent nosebleeds that are difficult to stop.
  • Many large or deep bruises.
  • Bleeding into the joints or muscles causing pain and swelling.
  • Bleeding from the gums.
  • Bleeding after injections, vaccinations.
  • Too much bleeding after injuries, cuts, and during surgery.

Causes of hemophilia

In most cases, hemophilia is hereditary. However, in rare cases, hemophilia may not be congenital, but acquired. Acquired hemophilia is an autoimmune disease in which the immune system attacks the clotting factors, and they cannot function properly.

Acquired hemophilia can be caused by pregnancy, cancer, autoimmune conditions, multiple sclerosis, as a reaction to certain medications.


Hemophilia is much more common in men than in women.

Hemophilia is caused by a defect in the genes responsible for blood clotting factors. In the most common types of hemophilia, the defective genes are found on the X chromosome.

The X chromosome is one of the sex chromosomes responsible for the biological sex of a child. Each person has two sex chromosomes, one from each parent. Girls inherit the X chromosome from their mother and the X chromosome from their father – XX. Boys inherit the X chromosome from their mother and the Y chromosome from their father – XY.

If a boy receives an X chromosome with a defective gene from his mother, he will have hemophilia. Girls with one affected X chromosome in most will be a “carrier” of hemophilia because they have a second healthy X chromosome. A carrier means that the girl will not have symptoms of hemophilia, but she can pass the disease on to her children.

It is very rare for females to have hemophilia. Hemophilia occurs when a woman has both X chromosomes with defective genes.

Sometimes, however, a woman with one affected X chromosome will develop symptoms of hemophilia if the clotting factors are moderately decreased.

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