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Hemophilia

I. Background:

Hemophilia A (HA) is considered the classic form of hemophilia, and hemophilia B (HB) is termed Christmas disease. HA is a consequence of a congenital deficiency of factor (F) VIII, and HB is a consequence of a congenital deficiency of FIX. This deficiency results in insufficient generation of thrombin by FIXa and FVIIIa complex through the intrinsic pathway of the coagulation cascade.

The classification of the severity of hemophilia has been based on either clinical bleeding symptoms or plasma procoagulant levels, which is the most widely used classification (see table 1). Clinical bleeding symptom criteria have been employed because, occasionally, patients with FVIII or FIX levels less than 1% exhibit little or no spontaneous bleeding and appear to have clinically moderate or mild hemophilia. Furthermore, the reverse is true for patients with procoagulant activities of 1-5%, who may present with symptoms of clinically severe disease.

Table 1. Severity, Factor Activity, and Hemorrhage Type

|Classification |Factor Activity, % |Cause of Hemorrhage |

|Mild |>5 |Major trauma or surgery |

|Moderate |1-5 |Mild-to-moderate trauma |

|Severe | ................
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