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Hemophilia - Blood everywhere |
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Written by Lev Prasov
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May 13, 2006 at 06:38 PM |
Hemophilia is a group of genetic disorders that result from deficiencies in various clotting factors. The lack of clotting factors leads to significant bleeding all over the body.
When we get a bruise or a cut, it may bleed for a little while, but usually the blood will clot and phagocytic white blood cells will mop up the debris. For much of the European royalty, this was not the case, as they suffered from a genetic bleeding disorder called hemophilia (also called haemophilia). While the queens and princesses were largely unaffected, many of their sons had problems with bleeding. The genetic tree (Figure I) is believed to have been started through a random mutation acquired by Queen Victoria. She passed the gene on to her son (who was affected with the disease) and several of her daughters. The daughters, in turn, spread this "royal disease" throughout much of the European royalty. As a result, many of the males in the royal family died early due to excess bleeding.
 Figure I: The genetic tree of hemophilia in the royal family. ( Image courtesy of Wikipedia)
Hemophilia is a class of primarily X-linked genetic disorders that result from a deficiencies in clotting factors. As can be seen from the genetic tree of the royal family (Figure I), hemophilia largely affects males. There are three major forms of the disease, each due to different clotting factor defects. Hemophilia A and B are the predominant forms, reflecting losses in Factor VIII and Factor IX, respectively. Both of these proteins are vital in the coagulation cascade. They serve as intermediate steps in the activation of thrombin. In turn, thrombin activates fibrinogen to fibrin, which forms the sticky substance that holds a clot together. As a result, deficiencies in these factors lead to excessive bleeding.
Too much bleeding is a major concern for anyone, but it is especially a problem in hemophilia. Small injuries such as a bumps or cuts invariably lead to damage of capillaries and small blood vessels. Normally, small clots plug the leak. In hemophilia, however, these injuries can lead to profuse bleeding in muscles and joint spaces. Having too much static blood can in turn damage these tissues and provide a mechanical barrier, leading to muscle pain and decreased mobility in the joints. Blood can also leak into the kidneys leading to hematuria (blood in the urine). The stomach and intestines constantly have low amounts of damage from food and digestive enzymes. In hemophilia, this minor damage can result in gastrointestinal bleeding, which often presents as bloody diarrhea. The most severe complication of hemophilia is bleeding around the brain. The brain is in a closed container (the skull), so any blood that accumulates in the brain must do so at the expensive of brain tissue. In effect, blood can push aside vital components of the brain, leading to nerve fiber compression and ultimately loss of brain function.
While there is no cure for hemophilia, it can be treated. The patients are missing normal clotting factors, so the simple solution is to periodically infuse these factors into their blood to facilitate normal blood clotting. In the 1970s and 1980s, normal clotting factors were primarily derived from purified human blood. Unfortunately, some of these blood samples were contaminated with HIV and Hepatitis B. Since that time, techniques have been used to insure that blood is not contaminated. Recombinant forms of the various clotting factors have recently been developed, but these are still extremely expensive. Ultimately, as with many genetic diseases, gene therapy seems to be the most promising cure for hemophilia. However, it has yet to be attempted, especially given that intravenous infusions seem to be effective at controlling the disease.
For more information on Hemophilia, check out the following resources:
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Last Updated ( Sep 23, 2007 at 04:00 PM )
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