“My nephew has just been diagnosed as having haemophilia – what is this?"
Haemophilia is the name of a family of genetic conditions that impair the body's ability to control blood clotting. It is passed on in families and there are about 6000 people in the UK with the condition. Blood clots form as a result of several proteins coming together in the right place at the right time. These proteins are known as ‘factors’ and are given numbers that are written as Roman numerals.
In the most common form is haemophilia A. In this condition, the clotting protein known as factor VIII is absent. Haemophilia B, is also known as factor IX deficiency or Christmas Disease, and is the second most common type of haemophilia.
Haemophilia is known as an X linked genetic disorder. This means that the faulty protein is due to a problem with a gene found on the X chromosome. Women have 2 X chromosomes, so if one is faulty, the other usually has a normally working gene that can produce normal forms of the protein and the woman will have no problems. Women with the faulty gene may then pass on a copy to their son. Because men have one X chromosome and one Y chromosome, if the X chromosome carries the faulty gene, they have no ‘back up’, and so they do not produce the correctly functioning proteins, leading to haemophilia. Queen Victoria is believed to have had a faulty gene, leading to several of her male descendents having the condition.
This relationship of the condition running in men only has been recognised for a very long time. In the sacred Jewish text, the Talmud, it states that if 2 brothers in a family had died from uncontrolled bleeding, then any other males did not need to have a circumcision.
There can be variable forms of the condition, depending on how faulty the protein is. In some people it is only a little faulty, and they may not notice a problem. In people in whom the protein is very abnormal, they may have severe problems, and their blood may not clot after even a minor wound. In the times before this was recognised, these individuals may have died at a young age. Before 1986 these clotting factors were taken from donated blood. However, there were some people who gave blood who had hepatitis C and HIV which led to a large number of people with haemophilia being infected. These days, however, there are ways of artificially manufacturing the missing protein and replacing them in people with haemophilia, allowing them to lead completely, risk free normal lives.
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