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Q: A friend of mine has hemophilia and is periodically treated with blood infusions. He told me that women do not usually have this disease. Is this true? Can you tell me something about the disease?
A: Hemophilia is a birth disorder in which certain factors necessary for the clotting of the blood are not present. In particular, there are two forms of hemophilia that are to be distinguished from one another. The first form is referred to as hemophilia A, and is characterized by the presence of low levels or absence of factor VIII (factor 8), which is one of the factors required for blood to coagulate. The other form of hemophilia, referred to as hemophilia B, is characterized by the presence of low levels or absence of factor IX (factor 9), another important factor necessary for the clotting of blood. Both of these types of hemophilia are characterized by bleeding, which may occur anywhere in the body. The most common sites of bleeding are joints, muscles, and the intestinal system. Hemophilia may be more or less severe. In its severe form, patients may bleed spontaneously or in response to mild trauma. In its less severe form, patients only bleed in response to major trauma or surgery.
Both hemophilia A and B present clinically in the same fashion. They both lead to disturbances in the clotting of the blood. The only way to distinguish these two diseases is by measurement of factors 8 and 9, to determine which is decreased (or absent) Hemophilia is a birth disorder which is linked to the sex X chromosome. Quite generally, it is known that to have females have two X chromosomes. On the other hand, males have an X and a Y chromosome. Hence, it is clear that this disease is usually manifested in males, since in this case the disease would occur whenever an abnormal X chromosome is present. On the other hand, in order for the disease to be present in a woman, both X chromosomes must be abnormal, since this disease is also recessive, meaning that both X chromosomes must be affected before the disease presents itself symptomatically.
This thus explains why this disease usually does not occur in women, since this disease could then only occur if a male which has the disease marries a woman which has the disease or is carrying an abnormal chromosome. An important issue in hemophilia is identifying females which are carriers of the abnormal X chromosome. These females can generally be identified with a blood test .
Treatment of hemophilia consists on infusion of the appropriate missing factor. Unfortunately, many hemophiliacs have developed HIV infection, because of factor infusions obtained from blood containing the HIV virus, before testing for this virus became possible. In addition these factor concentrates are now heat treated to further reduce the likelihood of transmission of the HIV virus. In addition, there are presently some new techniques, the so called recombinant techniques, which appear safe and effective, though expensive, and should impose no risk of HIV virus transmission.
Updated: 09/12/99
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