Haemophilia is a blood condition that means bleeding does not stop. The bleeding occurs because the blood does not clot. A person with a small cut or internal bleed (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"
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.