Discover more about the science behind different types of blood disorders, from haemophilia to rare clotting factor deficiencies and women living with haemophilia.

Haemophilia is a rare genetic blood disorder, in which the blood does not clot as it should. It can also lead to sponteneous internal and external bleeding. People with haemophilia are missing or do not have enough clotting factor, a protein in the blood that helps to control bleeding and clotting.

Haemophilia is divided into two different types, A and B, both of which predominantly affect men. The most common type of haemophilia is 'haemophilia A', and affects around one in every 10,000 males. Haemophilia A is caused by people not having enough clotting factor VIII (factor eight). Haemophilia B is less common than haemophilia A, affecting around one in 50,000 males. A person with haemophilia B does not have enough factor IX (factor nine).

Depending on how much of the clotting factor a person has, will determine whether their condition is classed as mild, moderate or severe. For example:

• Severe haemophilia means that factor levels are less than 1%
• Moderate haemophilia means that factor levels are 1–5%
• Mild haemophilia means that factor levels are 6–30%

For people with severe haemophilia, these incredibly low levels of factor (<1%) mean that they will bleed following injury, but what can be most difficult is that people will have frequent spontaneous bleeding episodes, often inside their body.

Due to the genetics of haemophilia, it occurs mostly in men; however, women can be carriers and also experience symptoms. 

We all have two chromosomes which we inherit from our parents. Females inherit two X chromosomes, one from their mother and one from their father (XX). Males inherit an X chromosome from their mother and a Y chromosome from their father (XY). The gene for haemophilia is located only on the X chromosome. So, if a son inherits an X chromosome carrying haemophilia from his mother, he will have haemophilia. A father with haemophilia cannot pass it on to his sons, but will pass the gene to his daughters. Because females have two X chromosomes, even if they inherit a haemophilia gene, they have another healthy X chromosome to take over, instead they will be a carrier. Carriers have around half the normal amount of factor VIII and factor IX and can also suffer symptoms

Haemophilia is well documented in males; however, it is often not recognised in women, who may also be living with symptoms. Recent research has suggested that some carriers have increased and longer bleeding during menstruation compared with non-carriers. These female carriers may suffer a number of symptoms including:

• Bruising more easily
• Prolonged bleeding after surgery
• Serious bleeding after trauma and longer time to heal
• More likely to require an iron supplement or to undergo hysterectomy and are more likely to have bleeding following childbirth.

Along with the physical symptoms, there may be a psychological and mental health impact from being a haemophilia carrier - discover how Olivia lives with being not only a carer for her son Harry, but also being a haemophilia carrier.

Acquired haemophilia is a rare condition that affects both men and women in adult life. It is caused by an auto-antibody, produced by the immune system, which inactivates factor VIII proteins (factor VIII is a clotting factor protein in the blood that helps to control bleeding and clotting).

Acquired haemophilia can lead to significant bleeding; however, the bleeding pattern seen is very different from the more common haemophilia. Bleeding into the joints is much less common, the person will bleed into the skin and soft tissues. Discover how Linda was diagnosed and what it is like to be living with acquired haemophilia.

Clotting factor deficiencies are rare disorders in which one of several clotting factors is missing or not working properly. These rare diseases a still being learned about within the scientific community as they are diagnosed so rarely. Find out more about living with rare clotting factor deficiencies.