Haemophilia is a blood condition that means bleeding does not stop. The bleeding occurs because the blood does not clot. People with hemophilia lack proteins in the blood that make scabs and blood clots. A person with a small cut or internal bleeding (bruise) could bleed to death. They do not bleed more than a normal person, but they bleed for much longer. The word comes from the Greek words haima ("blood") and philia ("to love"). To treat this, an affected person can get a blood donation from someone without hemophilia. The donor’s blood has clotting proteins and can temporarily make a normal scab. 30% of hemophilia A and B cases are the first person in their family to have hemophilia which is the result of an unexpected mutation (this means that there is an unexpected change in the body).
There are 3 types of haemophilia:
- Haemophilia A - about 90% of cases. There is no blood clotting ability.
- Haemophilia B - not as severe, but much less common. There is not enough blood clotting ability.
- Haemophilia C - caused by not one, but two recessive (weak) genes.
Haemophilia A happens in about 1 in 5,000–10,000 male births. Haemophilia B happens in about 1 in every 20,000–34,000 male births.
Genetic defects on the X chromosome affect males because they have only one X chromosome. In females, a recessive gene is usually masked by a normal gene on the other X chromosome. The Y chromosome does carry some genes, but far fewer than the X chromosome. Defects of this type are called "sex-linked" in genetics. There is no cure for this disease but there are different treatments available around the world.
A person with haemophilia is called a haemophiliac.