Hemophilia is a genetic disorder in the blood-clotting system, characterized by bleeding into joints and soft tissues, and by excessive bleeding into any site experiencing trauma or undergoing surgery. The two types - Hemophilia A and B - are clinically indistinguishable. Both have the same type of bleeding manifestations, and both affect males almost exclusively. Injury to a blood vessel is a serious problem for the body. Blood may begin to leak out of the injured area. The body has developed a mechanism for protecting itself from this kind of damage. The mechanism involves the formation of a blood clot over the injured area to prevent loss of blood. Blood clotting is a very complicated process. It involves blood cells known as platelets and at least twenty different chemical compounds. The first step in the clotting process is the formation of a temporary plug. The plug is formed of platelets that stick to the damaged area. The plug is soon covered by a more permanent structure consisting of fibrin. Fibrin is tissue that acts like a permanent patch or bandage on the injured area. The production of fibrin takes place in a series of steps that requires thirteen different chemicals. These chemicals are known as "clotting factors." In order for fibrin to form, all thirteen clotting factors must be present in the blood. Patients may lack one or more clotting factors, or their bodies may not make enough of a clotting factor, or the clotting factor may not be made correctly. In any one of these cases, the patient's body is not able to make fibrin. An injury to a blood vessel cannot be properly repaired. Blood continues to escape from a damaged blood vessel.
Hemophilia is a genetic disorder. A genetic disorder is a medical condition in which a person has one or more abnormal genes. Genes are the chemical units that are present in all cells. They tell cells what functions to perform. The normal mechanism for blood clotting is a complex series of events involving the interaction of the injured blood vessel, blood cells called platelets, and over 20 different proteins that also circulate in the blood. When a blood vessel is injured in a way to cause bleeding, platelets collect over the injured area, and form a temporary plug to prevent further bleeding. This temporary plug, however, is too disorganized to serve as a long-term solution, so a series of chemical events result in the formation of a more reliable plug. It is stated, "The final plug involves tightly woven fibers of a material called fibrin" (The Gale Encyclopedia of Science, 2011). The production of fibrin requires the interaction of a variety of chemicals, in particular a series of proteins which are called clotting factors. At least 13 different clotting factors have been identified (2011). For example, everyone has certain genes that tell cells how to make clotting factors. There is one gene for making clotting factor I, one gene for clotting factor II, one gene for clotting factor III, and so on.
The genes for making clotting factors are located on X chromosomes. This means that males are more likely to have hemophilia than females since they have two X chromosomes. Femlaes may inherit one defective X chromosome, but will probably not inherit two defective X chromosomes. Their normal X chromosome will still carry the correct instructions for making clotting factors. Males, however, carry only one X chromosome meaning if the X chromosome a male inherits is defective, he will not have a normal X chromosome to compensate for the defective one. His cells will not receive the correct instructions for making clotting factors. For this reason, hemophilia is almost entirely a disorder in males (2007). The condition very rarely occurs among women. Even if women carry one defective X chromosome, they will not have the disorder. However, they will have the ability to pass the disorder on to their children. For that reason, a female with just one defective X chromosome is said to be a carrier for the disorder. Also, About 30 percent of all people with hemophilia A or B are the first members of their family to ever have the disease. These individuals have the unfortunate occurrence of a spontaneous mutation. In their early development some random genetic accident caused a defect in their X chromosome. Once a genetic mutation takes place, offspring of the affected person can inherit the newly-created, flawed chromosome. As for the specific gene, "Hundreds of defects in the FVIII gene have been shown to cause hemophilia" (Genetics, 2008). Inversion of the gene is the most common mutation. The same types of defects are found in the FIX gene. This makes population screening for hemophilia impractical since are too many possible mutations to screen for. However, affected members of a given family will all have the same defect in the gene. Gene analysis is used to determine which defect is present in the FVIII or FIX gene of a particular family with hemophilia, so that one can look for this defect in possible carrier females.
The primary symptom of hemophilia is bleeding. The amount of bleeding that occurs depends on how serious the patient's condition is. In the most severe cases, bleeding can cause serious health problems, including death. In the case of severe hemophilia, the first bleeding event usually occurs prior to 18 months of age. In fact, toddlers are at particular risk, because they fall so frequently. As a child becomes more active, bleeding into the muscles may occur. This form of bleeding is more serious and more painful. Muscle bleeds cause pressure on nerves. This pressure can cause pain, numbness, and damage to nerves. Some of the most problematic and frequent bleeds occur into the joints, particularly into the knees and elbows. Repeated bleeding into joints can result in permanent deformities. Mouth injuries can result in compression of the airway, and therefore can be life-threatening. A blow to the head, which might be totally insignificant in a normal individual, can result in bleeding into the skull and brain. Because the skull has no room for expansion, the individual is at risk for brain damage due to blood taking up space and exerting pressure on the delicate brain tissue.
Abnormal bleeding patterns are usually the first clue that a person has hemophilia. Simple bumps and bruises that result in uncontrolled bleeding are a common early symptom of hemophilia. Diagnosis of hemophilia is confirmed with blood tests. These tests are able to measure how much of various clotting factors are present in the blood and how quickly they work to produce clots. These tests can be used to diagnose the type of hemophilia a person has and the seriousness of the condition. This makes the future of people with hemophilia is very hard to predict. For one thing, the severity of the condition varies widely - from very mild to very severe. Also, patients differ in their degree of activity where the more active an individual is, the more likely injury is to occur.
The frequency of treatment depends on the severity of the disease. People with mild hemophilia may require treatment only when they have been injured. They may also need treatment before surgery or dental work. Patients with more severe forms of the disorder may require regular injections of the missing factor (2007). The use of injections to treat hemophilia is accompanied by some possible complications. For example, in some cases, the body's immune system begins to make antibodies against factors contained in the injections. Antibodies are chemicals produced by the immune system to protect the body against infection. The immune system may become confused and react as if the injected factors are bacteria, viruses, or other harmful materials. Theoretical cures for hemophilia would include gene therapy. People with hemophilia have low levels of certain blood clotting proteins, usually factor 8 or factor 9, which are necessary for clotting of the blood. These blood clotting proteins are produced continually in a person without hemophilia. Most of these proteins are produced in our livers. But other cells contribute to the production also. Hemophilia is on the top of the list of disorders that may by cured with gene therapy because of it’s simplicity. It is only one missing blood clotting protein caused by one genetic mutation. Scientist would remove cells from a person with hemophilia. Usually liver cells, but other cells, muscle, fat etc. have proven to be successful as well. The scientists then alter the cells genetically by inserting new genetic material into them that reprograms the cells. This new genetic material instructs the cells to produce factor 8 or 9. The cells are then reinserted into the person with hemophilia and the person with hemophilia would no longer has hemophilia.