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"How many people are affected by hemophilia?"

ZocdocAnswersHow many people are affected by hemophilia?


I have hemophilia. I am 28 and have never run into anyone else with it. I'm sure there are people out there. Is it really that rare?


The term hemophilia is most commonly applied to a group of two genetic disorders that affect blood coagulation. Hemophilia A is a genetic deficiency of Factor VIII, a protein involved in the cascade of chemical reactions that allows our blood to clot in response to vascular injury. Hemophilia B, also known as Christmas Disease, is a genetic deficiency of Factor IX, another protein in the clotting cascade.

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These are both recessive disorders inherited through the X chromosome. Although the diseases exhibit a range of severities among different individuals (owing to certain genetic differences in the mutations responsible for causing the disease in a given individual), the common feature of all hemophilias is that the time required for the blood to clot is increased. Because hemophilia is passed on the X chromosome, it is substantially easier to get a defective copy of the gene responsible for hemophilia if you are male (as males only have one copy of the X chromosome, there is no chance that a working copy could compensate for the defective copy, as can occur in females who have 2 X chromosomes). For this reason, virtually all patient with hemophilia are male, and although it is theoretically possible for females to have the disease, this is an exceedingly uncommon occurrence. The combined incidence (number of new cases diagnosed) is 1 in 5000 live male births. Of these, approximately 80% of hemophiliacs have hemophilia A. This translated to about 1 in 5000 to 1 in 10000 live male babies being diagnosed with hemophilia A and about 1 in 25,000 to 1 in 30,000 live male babies being affected by Hemophilia B. Generally speaking, hemophilia is considered an uncommon, but not a rare, disease. I would recommend you see either your primary care physician or a hematologist regularly to discuss questions like these about your disorder and to keep up to date about what treatment may be needed. Hemophilia is a potentially serious disorder and there is no substitute for evaluation and treatment in person by a licensed physician.

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