Hemophilia - Normal Blood Clotting, The Defect In Hemophilia, How Hemophilia Is Inherited, Symptoms Of Hemophilia - Diagnosis
tests occur determine disorder
Hemophilia is an inheritable disorder of the mechanism of blood clotting. Depending on the degree of the disorder present in an individual, excess bleeding may occur only after specific, predictable events (such as surgery, dental procedures, or trauma), or may occur spontaneously, with no initiating event.
Various tests are available to measure, under very carefully controlled conditions, the length of time it takes to produce certain components of the final fibrin clot. Tests can also determine the percentage of factors VIII and IX present compared to known normal percentages. Families with a positive history of hemophilia can have tests done during a pregnancy to determine whether the fetus is hemophiliac.
Additional Topics
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 which 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, how…
In hemophilia, certain clotting factors are either decreased in quantity, absent, or improperly formed. Because the clotting cascade uses amplification to rapidly plug up a bleeding area, absence or inactivity of just one clotting factor can greatly increase bleeding time. Hemophilia A is the most common type of bleeding disorder, and involves decreased activity of factor VIII. Three levels of fac…
Hemophilia A and B are both caused by a genetic defect present on the X chromosome (hemophilia C is inherited in a different fashion). About 70% of all individuals with hemophilia A or B inherited the disease. The other 30% have hemophilia because of a spontaneous genetic mutation. In order to understand the inheritance of these diseases, a brief review of some basic human genetics is helpful. All…
Various types of factors VIII and IX are available to replace a patient's missing factors. These are administered intravenously (directly into the patient's veins by needle). These factor preparations may be obtained from a single donor, by pooling the donations of as many as thousands of donors, or by laboratory creation through highly advanced genetic techniques. The frequency of t…
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