WHAT IS HEMOPHILIA?
Hemophilia is an inherited blood disorder passed from a parent to their child through genes, where a lack of clotting factor protein in the blood makes it difficult to control bleeding.
There are 13 main factors in blood that work together to produce a clot. If one factor is missing, the chain reaction is broken and clots will not form properly, causing a person with hemophilia not to bleed faster, but to bleed for longer periods of time.
If not treated early on, hemophilia can lead to crippling pain, internal bleeding into muscles and joints, severe joint damage, disability, and early death.
There are various levels of severity. A mild form of hemophilia may be having few bleeding episodes, but may require taking precautions if having surgery or after a serious injury. Severe hemophilia can lead to bleeding spontaneously when there is no obvious cause for the bleeding.
HOW IS IT DIAGNOSED?
Hemophilia is diagnosed by measuring the level of factor activity in the blood. If the mother is a carrier, testing can be done before a baby is born. Prenatal diagnosis can be done at 9 to 11 weeks by chorionic villus sampling (CVS) or fetal blood sampling at a later stage (18 or more weeks). Hemophilia A is diagnosed by testing the level of factor VIII coagulation activity in the blood. Hemophilia B is diagnosed by measuring the level of factor IX activity.
GENETICS OF HEMOPHILIA
Men with hemophilia pass the gene on to their daughters, but not to their sons. Men are generally more affected than women. Women who are carriers have a 50 percent chance of having a boy with hemophilia and a 50 percent chance of having a girl who is a carrier.
About one third of new cases are caused by a spontaneous mutation of the gene, which means that there was no history of hemophilia in the family before.
Hemophilia usually affects men because the hemophilia gene is carried on the same chromosome that determines whether a person is male or female. Men have an X and a Y chromosome and women have two X chromosomes. The genes for hemophilia A and B are on the X chromosome. Since women have two X chromosomes, if one does not work properly, the other X chromosome makes up for it. However, if the hemophilia gene is on both X chromosomes, then the women will have hemophilia.
TYPES OF HEMOPHILIA
There are two types of hemophilia: Hemophilia A, factor VIII (8) deficiency and Hemophilia B, factor IX (9) deficiency.
TREATMENTS FOR HEMOPHILIA
Hemophilia is a lifelong condition with no cure, but it can be treated by replacing the missing clotting factor in the blood. This is done by injecting a product that contains the needed clotting factor into a vein. Bleeding stops when enough clotting factor reaches the bleeding site. When bleeding is in the joint, it is very important that treatment is given as quickly as possible to prevent long-term damage.
Historically, these three have been used in the treatment of hemophilia:
- Whole Blood
In the United States, factor concentrates are used exclusively for Hemophilia A and Hemophilia B due to the increased safety and ease of use of these products over the whole blood or fractions of blood—plasma and cryoprecipitate.
Factor Concentrate - Recombinate and plasma derived
Factor concentrates are very effective, but expensive. They can be made from human blood (called plasma-derived products) or manufactured using genetically engineered cells that carry a human factor gene (called recombinant products).
There are several levels of purity (the concentration of factor), ranging from intermediate to very high depending on the manufacturing process. The therapeutic safety of each product depends on the methods used to prevent, remove, or inactivate viruses that may be present in the source plasma.
People with mild hemophilia A may also be prescribed desmopressin (also called DDAVP), a synthetic hormone that stimulates the release of factor VIII.
OTHER TREATMENTS FOR HEMOPHILIA
There is no cure for hemophilia yet, but gene therapy remains an exciting possibility for a partial or complete cure for hemophilia. There are many technical obstacles to overcome, but it is encouraging to see that clinical trials for both factor VIII and IX have begun.
Inhibitors are antibodies to factor VIII or factor IX that attack and destroy the factor VIII and IX proteins in clotting factor concentrates, making treatment ineffective. They appear almost exclusively in patients with severe hemophilia.
There is some controversy over the precise incidence (number of new cases) of inhibitor development, but it is generally accepted that around 15% of people with severe hemophilia A will develop inhibitors at some stage.
By contrast, inhibitor development in hemophilia B is very rare indeed, and seen in less than 1% of subjects. Most inhibitors emerge after relatively few treatments. In general, the more treatments a person has had without developing inhibitors, the less likely he or she is to develop an inhibitor.
Prophylaxis is the regular use of clotting factor concentrates to prevent bleeds before they start. Injections of clotting factor are given two or three times a week to maintain a constant level of factor VIII or IX in the bloodstream. Prophylaxis can help reduce or prevent joint damage.
In countries with good access to clotting factor concentrates, this is becoming the normal mode of treatment for younger patients, and can be started when the veins are well developed (usually between two and four years of age).
A port-a-cath, or implantable venous access device (IVAD), is placed under the skin, usually in the upper chest (but there are models which can be inserted into the arm). It has a small metal reservoir with a rubber diaphragm which is connected to a catheter and threaded into a large vein in the chest or arm. The entire device is surgically implanted under the skin so there is no catheter that hangs out of the body.
The device provides ready access to a vein for administering medications and fluids intravenously. It can also be used for collecting blood samples. The device is accessed by inserting a special needle through the skin and into the rubber diaphragm of the reservoir. The medication or fluid is injected into the device and it flows through the catheter into the vein.
These devices have made prophylaxis in hemophilia much easier because they eliminate the difficulty of “finding a vein” for infusion two to three times a week. However, there are risks involved with their use, the most worrisome being infection. Studies differ but some show an infection rate as high as 50%. Infections can usually be treated with intravenous antibiotics but sometimes the device must be removed.
Also, there are other studies that show a risk of clots forming at the tip of the catheter. Still, many families have chosen to use the device in spite of the risk because of the benefits. Like any other procedure, one must weigh the risks and benefits.
Some people with hemophilia do not exercise because they think it may cause bleeds, but exercise actually helps prevent bleeds. Strong muscles help protect someone who has hemophilia from spontaneous bleeds and joint damage.
Sports are an important activity for young people. However, some sports are riskier than others, and the benefits must be weighed against the risks. The severity of a person’s hemophilia should also be considered when choosing a sport. Sports like swimming, badminton, cycling, and walking are safe for most people with hemophilia, while sports such as football, rugby, hockey and boxing are not recommended for people with hemophilia.