Haemophilia is an inherited disorder in which there is a deficiency of a protein necessary for blood clotting. The protein is usually either Factor VIII (also known as anti-haemophilia factor) or Factor IX, although, rarely, other factors can be deficient. Factor VIII deficiency is also known as classical haemophilia or Haemophilia A, while factor IX deficiency is also known as Haemophilia B or Christmas disease.
Who gets haemophilia?
Both Haemophilia A and B mainly affect males. The deficiency is present at birth.
What are the symptoms of haemophilia?
Children with haemophilia bruise easily and relatively minor cuts may take a long time to stop bleeding. Spontaneous bleeding can occur into joints and muscles, leading to severe pain and long-term joint damage. Internal bleeding can also occur.
What causes haemophilia?
Haemophilia A and B are both caused by a fault in the gene responsible for the production of the appropriate protein. As both genes are carried on the X chromosome, they are often referred to as X-linked disorders. Girls have two X chromosomes, so, if, for example, they have a faulty gene for making factor VIII on one X chromosome, they usually have a normal gene on the other, so cannot have haemophilia. Boys, on the other hand, have only one X chromosome, so they only have one gene for making factor VIII (or IX). If this gene is faulty, they will have haemophilia. Girls with one copy of the gene for haemophilia are known as carriers.
Girls inherit one X chromosome from each of their parents. Boys, on the other hand, can only inherit their X chromosome from their mother. Hence, a man with haemophilia cannot pass it on to his sons, but all his daughters will be carriers, and there is a 50% chance of passing the gene for haemophilia onto each of their sons.
In about 70% of cases, there is a known family history of the condition. In the remaining 30%, however, there is no family history, so the faulty gene has appeared as a result of a spontaneous mutation occurring in either the mother’s egg or father’s sperm before the affected child was conceived.
How is haemophilia diagnosed?
The first symptom of haemophilia, particularly if is severe, is bruising easily. In less severe cases, suspicions may not be aroused unless there is extensive bleeding following an operation or an injury. A blood test showing low or absent levels of Factor VIII or IX is diagnostic.
If you have a family history of haemophilia, and are considering starting a family yourself, you should contact a haemophilia centre for information on pre-natal testing. Counselling is also provided at these centres. Addresses can be obtained from the Haemophilia Society at the address given below.
How is haemophilia treated?
Treatment is by replacement of the missing Factor, by injecting it directly into a vein. Parents are taught to do this for their children, and, later, children can do it for themselves. Treatment regimes vary, and are individually tailored.
It is important that people with haemophilia do not take aspirin as this further impairs blood clotting.