What is Haemophilia?

Haemophilia is an inherited bleeding disorder where blood doesn’t clot properly (inherited means it is passed on from parent to child through their genes). It is caused when the blood does not have enough clotting factor. This means that if a person with haemophilia injures themselves it takes longer for their blood to stop running (or clot). A clotting factor is a protein in the blood that controls bleeding.

A third of people who are born with haemophilia will be the first one in their family to get haemophilia, as something changed with their genes before they were born. It is also possible that something changed in their mother’s genes before she was born and she passed on the altered gene that caused haemophilia in the next generation.

There are two types of haemophilia and they both have the same symptoms:

  • Haemophilia A is the most common and is caused by not having enough of clotting factor VIII (8)
  • Haemophilia B, also known as Christmas Disease, is caused by not having enough of clotting factor IX (9)

Date last reviewed: 21/06/2012