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Different Types of Inherited Hemophilia

Alterations in Levels of Clotting Factors Cause Problem Bleeding

Mar 16, 2009 Kenneth Rosen

Mutations in the X-chromosome-linked genes for clotting factors VIII and IX lead to problems with blood clotting that range from mild to severe and life-threatening.

When someone suffers a cut, blood vessels are damaged and bleeding occurs. In a normal person, clotting factors in the circulating blood assist the platelets in starting the formation of a clot to staunch the bleeding. In a person with hemophilia, a reduction or absence of the needed clotting factors makes stopping the flow of blood more difficult.

Two Types of Inherited Hemophilia

Hemophilia A, also known as classic hemophilia, occurs as a result of a deficiency or absence of clotting factor VIII (and thus its other name, factor VIII deficiency). Hemophilia B, also known as Christmas disease, is a result of a deficiency in or absence of factor IX. The genes for both of these clotting factors are located on the X chromosome, making this what is known as a sex-linked mutation.

Inheritance of Hemophilia

Women have two X chromosomes; men have one X and one Y chromosome. For both types of hemophilia, where the mutant genes are carried on the X chromosome, a woman can be a “carrier” but show no signs of the disorder. If she passes on the X chromosome with the mutation to a male offspring, that son will have hemophilia because the father donates the Y chromosome. Thus, for a female carrier, her sons have a 50% chance of inheriting the disease. For a man with hemophilia, his male progeny will not have the disease, unless their mother is a carrier. This same male can have female offspring that become carriers of the disorder by virtue of inheriting his X chromosome. About 15,000 to 20,000 people are believed to be affected with hemophilia in the United States.

Treatments for Hemophilia

Hemophilia severity can range from mild to moderate to severe. The severity is dependent upon how much of the clotting factors can be found in the bloodstream. For those with severe hemophilia, administration of recombinant clotting factors is undertaken to combat serious bleeding episodes (the use of clotting factors purified from donated blood has been minimized to prevent adventitious infection with blood-borne pathogens). If not done, spontaneous bleeding events or injuries causing internal bleeding into joints or other organs including the brain can lead to serious effects or even death. For those with mild forms of hemophilia, they may have prolonged bleeding times but generally do not have life-threatening bleeding episodes. For children with severe hemophilia, they can be given preventive dosages of clotting factors to minimize the risk of severe bleeding episodes.

As always, speak with your family physician or hematologist to discuss any medical problem including hemophilia. To learn more about hemophilia you can visit the websites of the National Hemophilia Foundation (NHF) or the US National Heart Lung and Blood Institute (NHLBI).

The copyright of the article Different Types of Inherited Hemophilia in General Medicine is owned by Kenneth Rosen. Permission to republish Different Types of Inherited Hemophilia in print or online must be granted by the author in writing.