Haemophilia is an inherited bleeding disorder where the blood doesn't clot properly. It is caused when blood does not have enough clotting factor. A clotting factor is a protein in blood that controls bleeding.

There are two types of haemophilia. Both have the same symptoms.

Haemophilia A is the most common form and is due to having reduced levels of clotting factor VIII (8).

Haemophilia B, also known as Christmas Disease, is caused by having reduced levels of clotting factor IX (9).

Haemophilia is not contagious.

In Australia there are approximately 2600 people with haemophilia, who are nearly all male. Haemophilia in females is very rare.

Bleeding is most commonly internal. The deficiency in clotting factor produces a wide range of bleeding episodes, usually into the joints or muscles. These bleeding episodes, or “bleeds”, may occur spontaneously, or as a result of trauma or injury. Specialised treatment is needed to help blood clot normally and is often infused or injected into a vein. If internal bleeding is not quickly stopped with treatment, it will result in pain and swelling. Over a period of time bleeding into joints and muscles can cause permanent damage such as arthritis, chronic pain and joint damage requiring surgery.

Levels of severity

There are 3 levels of severity in haemophilia: mild, moderate and severe. The level of severity depends on the amount of clotting factor in the person's blood. A person with haemophilia will have the same level of severity over their lifetime, e.g. a person with severe haemophilia will always have severe haemophilia. Within a family, males with haemophilia will also have the same level of severity, e.g. if a grandfather has severe haemophilia and his grandson has inherited haemophilia, his grandson will also have severe haemophilia.

The normal range of factor VIII and factor IX in a person's blood is between 50% and 150%.

Levels of severity of haemophilia
Mild haemophilia: 5-40 per cent of normal clotting factor
  • Usually only have bleeding problems after having teeth taken out, surgery or a bad injury or accident.
  • Might never have a bleeding problem.
Moderate haemophilia: 1-5 per cent of normal clotting factor
  • Might have bleeding problems after having teeth taken out, surgery or a bad injury or accident
  • May have bleeding problems after minor injuries such as sporting injuries
  • Rarely have a bleed for no obvious reason.
Severe haemophilia: less than 1 per cent of normal clotting factor
  • Often have bleeds into joints, muscles and soft tissues
  • Can have bleeds for no obvious reason, as well as after surgery, dental work or injuries including minor bumps or knocks

Haemophilia inheritance

Haemophilia is an inherited condition and occurs in families; however, in 1/3 of cases it appears in families with no previous history of the disorder. The haemophilia gene is passed down from parent to child through generations. Men with haemophilia will pass the gene on to their daughters but not their sons. Women who carry the haemophilia gene can pass the haemophilia gene on to their sons and daughters. Sons with the gene will have haemophilia. Some women and girls who carry the gene may also experience bleeding problems.

The diagrams below may assist in understanding this. The solid blue and red males are those with haemophilia; the solid red and blue females carry the gene.

haemophilia inheritance diagram

With appropriate treatment haemophilia can be managed effectively.

Last Reviewed: 01/01/2013

Reproduced with kind permission from Haemophilia Foundation Australia.


Haemophilia Foundation Australia. Haemophilia. Last reviewed January 2013. http://www.haemophilia.org.au/bleedingdisorders/cid/2/parent/0/pid/2/t/bleedingdisorders/title/haemophilia (accessed May 2013).