The term "haemophilia" covers a whole range of blood clotting disorders. Our blood needs to clot to seal any wound from infection, and to stop the person from bleeding to death.

There are various types of haemophilia, mostly involving a lack of one or more "factors" in the blood that make it clot when a person is cut. A person may have mild or severe haemophilia, depending on how low the levels of clotting factors are in their blood.

People with haemophilia don't bleed more than anybody else, but if they're cut, they can't stop bleeding. They also tend to bruise more easily, because a bruise is really a form of internal bleeding, and a person with haemophilia will bleed for longer.

A person needs a blood test to tell if they have haemophilia, which detects the clotting factors in their blood. With mild haemophilia, you may not know about it until you have surgery, dental extractions or some major injury.

You cannot catch haemophilia, but you may inherit it from your parents.
Only males can have haemophilia, but both males and females carry the genetic defect.

Here's how it works:

The genes in our cells are arranged in long chains, called "chromosomes". We're interested in just two chromosomes: called "X" and "Y" because of their shape.

The "X" chromosome carries instructions for the body to produce clotting factors. If an "X" chromosome has this part damaged, then the instructions will be missing, and the person may have haemophilia.

Notice that we said "may have". This is because females have two "X" chromosomes, so their other "X" chromosome has the instructions and thus they can make clotting factors normally.

However, males have an "X" and a "Y" chromosome. This means that if they have a damaged "X" chromosome, they have no instructions anywhere about how to make clotting factors, and thus the person has haemophilia.

A father with haemophilia will always pass the gene on to his daughters, but they won't haved haemophilia (they'll get his "X" chromosome, and be a carrier). but sons will not be affected (they get his "Y" chromosome, which is normal).

A mother who is a carrier (with a damaged "X" chromosome) has a 50:50 chance of passing the gene on to her children only her sons may have haemophilia. Her daughters may be carriers.

There's also a condition called "von Willebrand disease" which can affect both males and females. This is a blood clotting deficiency along with wound repair problems.

The basic treatment when a bleed happens is an injection of the missing "clotting factor". As people get older, they learn to give these injections themselves, and unless the bleed is serious they may not need to go to hospital.

The sooner the injection is given, the better, so that permanent damage to joints and muscles is avoided.

The "clotting factors" are often stored as dried powder, and mixed with sterile water when need for an injection. Once mixed, the clotting factors only last for a few hours, so the person may need several injections to deal with a major bleed. Of course, most people's bodies make their own clotting factors all the time.

Apart from the risk of bleeding too much when injured, a person with severe haemophilia can bleed internally, which causes problems when they bleed into a joint. This is because blood is slightly acid and will attack the joint, leading to arthritis.

When bleeding into a joint happens, the person may feel an ache or tingle in that area. Unless it's treated fast, this will develop into stiffness and swelling, and a great deal of pain.

Haemophiliacs use clotting factors made from blood donations. Nowadays, the products are treated to remove any viruses before being used. before this, there was a risk of diseases such as hepatitis (a nasty liver condition) or even HIV, possibly leading to AIDS.
There are many haemophiliacs who are infected with
these through no fault of their own.