A B C D E F G H I J K L M N O P R S T U V W

HAEMOPHILIA

What is Haemophilia ?

Haemophilia is an inherited bleeding disorder. It is due to a deficiency of a blood protein essential for blood clotting. The deficient protein may be clotting factor VIII or clotting factor IX (factor IX deficiency is also sometimes called Christmas disease). Only male children are severely affected. Bleeding occurs easily and is prolonged. As affected babies start to crawl and knock themselves, they often develop large bruises. Bleeding may occur spontaneously (in the absence of any injury). The commonest places for spontaneous bleeding to occur are the joints and muscles. The child may develop a swollen and painful joint or may be unwilling to move one of his limbs because of pain. As children grow and gain experience of the disease, they learn to recognize by the onset of pain that bleeding into a joint has started. This is before any signs can be detected by a doctor. Not all people with haemophilia are severely affected. With mild haemophilia, there will not be spontaneous bleeding. However, one is likely to have prolonged bleeding after injury or operations.

How does Haemophilia occur ?

A person's sex is determined by a pair of chromosomes, the sex chromosomes. One of these is inherited from each parent. Females have two X-chromosomes and males have one X and one Y. A boy will have inherited the X-chromosome from his mother and the Y-chromosome from his father. The X-chromosome carries many genes which are nothing to do with sex, including the factor VIII and factor IX genes. Because boys have only one X-chromosome, they have only one gene for making factor VIII. They inherit this gene from their mother. If this gene is abnormal, they can make no factor VIII, or very little. So they have haemophilia. Girls have two factor VIII genes, one on the X-chromosome inherited from their mother and one on the X-chromosome inherited from their father. Even if one of these is abnormal, they will still have one normal factor VIII gene on the X-chromosome from the other parent. This means they can make enough factor VIII for there to be no problem with blood clotting. A girl with one abnormal factor VIII gene does not have haemophilia. However, she is called a "carrier" for haemophilia because she can pass on the abnormal gene to a son. The level of factor VIII or factor IX in carriers is very variable and some may need treatment when having surgery or after accidents. It is important that any possible carriers have their factor VIII or factor IX level checked, as they may be completely unaware that it is low.

Why does Haemophilia occur ?

In many families, the haemophilia can be traced back through several generations. However, in about 30% of cases no one else in the family has been affected before. It seems that a change (mutation) has occurred in the mother's ovum or egg before conception of the affected baby. No one knows why this happens.

Treatment Involved for Haemophilia

Treatment involves replacement of the missing factor VIII. This is done by giving an injection of this chemical, which is usually prepared from normal donated blood. It is now also possible to make factor VIII artificially. This is referred to as recombinant factor VIII. It is currently more expensive than factor VIII extracted from plasma but is likely to be used more and more in the next few years. It is not practicable to give factor VIII often enough to keep the level in the blood normal all the time. In the past, factor VIII and factor IX have been given only at the time of bleeding. Now that more of these products are available, it is possible to use them also for prevention. This means giving factor VIII and factor IX regularly (two or three times per week) whether or not a bleed is present. In most cases this totally abolishes spontaneous bleeds and prevents long-term joint damage. Most families soon become very skilled at giving factor VIII to affected children. Sometimes, children can learn to give their own treatment at quite a young age. Factor VIII is supplied as a powder which is dissolved before injection. This can be kept at home and taken on holiday, so that treatment can be given as soon as a bleed occurs. If bleeding episodes are treated early, then they usually settle either with a single injection or with two or three injections given 12 to 24 hours apart. Replacement of factor VIII is also given before and after surgical operations or tooth extraction. DDAVP is another drug which can be given by injection. It has the effect of raising the patient’s own level of factor VIII in the body for a short time. It can be used instead of factor VIII replacement in mildly affected haemophiliacs who need tooth extraction or minor surgery. DDAVP is not effective in factor IX deficiency. Anti-fibrinolytic drugs are substances which make blood clots stronger. They are often given after tooth extraction or surgery in haemophiliac patients. They are usually given as tablets, or sometimes as mouthwash. There are many other important aspects of management. Care of the joints is important, to prevent deformity. Care of the teeth is important and dental work should be done after a dose of factor VIII. Counselling about school, work and outside activities is needed. For example, contact sports should be avoided. On the other hand, swimming is beneficial as it encourages muscle development without risk of injury. Patients are usually under the care of a haemophilia centre where expert advice is available on all these matters.

During Treatment for Haemophilia

The most important point is to make sure bleeding episodes are treated early. Patients should always keep a supply of factor VIII handy. They should contact their doctor if any pain does not settle quickly, if a very painful joint develops, or if there is any other kind of bleeding. There are usually no side-effects with factor VIII injections. Haemophiliacs should avoid contact sports and occupations where there is a risk of physical injury, but can otherwise lead normal lives. The factor VIII used in this country is now treated during its preparation. This kills viruses, including the AIDS virus, and there is now very little risk of infection as a result of factor VIII treatment. Failure to respond to treatment may indicate that an inhibitor has developed. Inhibitors are antibodies to factor VIII or IX which neutralize their action and can make treatment extremely difficult. They require prompt treatment by the haemophilia centre.

If Haemophilia is Left Untreated

Severe bleeding could occur and could be life threatening. Repeated bleeding into joints would cause joint damage and deformity.

Effects on Family of Haemophilia

Because haemophilia is an inherited disease, the doctor will suggest that all family members are tested to see if they are carriers of the gene. Counselling for affected families is available through haemophilia centres. If a woman who is a carrier of haemophilia becomes pregnant, tests are available in early pregnancy to determine whether a male foetus is normal or has inherited haemophilia. This is called antenatal diagnosis.