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May 2013

Hemophilias are bleeding disorders in which the blood does not clot properly due to a low level or complete absence of certain clotting factors. Hemophilia is usually inherited, but rarely, can be acquired. There are several types of hemophilia. The most common are:

  • Hemophilia A — reduced or absent clotting factor VIII
  • Hemophilia B — reduced or absent clotting factor IX

Hemophilia A and B are X-linked autosomal recessive disorders. A male who has a faulty hemophilia gene on his X chromosome will have hemophilia. A female must have the faulty gene on both of her X chromosomes to have hemophilia, which is very rare. If a female has the faulty gene on only 1 of her X chromosomes, she is a "hemophilia carrier” and can pass the faulty gene to her children.

Signs and symptoms of hemophilia vary, depending on the severity, but may include bleeding for an extended period of time after an injury, large or deep bruises, and internal bleeding that can damage organs, tissues, and joints.

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