Hemophilia is a hereditary genetic disorder characterized by a deficiency or absence of one of the clotting proteins in plasma (the colorless fluid part of the blood). The result is delayed clotting or excessive bleeding in the patient with hemophilia. While deficiencies of any of the clotting proteins can occur, factor VIII (FVIII) deficiency (Hemophilia A/ Classic Hemophilia) and factor IX (FIX) deficiency (Hemophilia B/Christmas disease) are the most common. Factor VIII deficiency is about four times more common than Factor IX deficiency.
Hemophilia and genetics
Hemophilia is a sex-linked disorder. The abnormal gene responsible for hemophilia is carried on the X chromosome. Females have two X chromosomes, while the male has one X and one Y chromosome. What this means is that each daughter of a carrier mother has a 50/50 chance of being a carrier and each son of a carrier mother has a 50/50 chance of inheriting hemophilia. The daughters of a father with hemophilia must be a carrier, and the father cannot pass hemophilia on to his son.
In about one-third of hemophilia cases, there is no family history of the disease. Such cases are thought to be the result of a recent genetic mutation.
Levels of severity
The amount of bleeding that can be expected in a individual with hemophilia depends on the severity of the deficiency. Normal plasma levels of FVIII and FIX range from 50–150 percent. Levels of severity include:
- Severe: People with no measurable FVIII or FIX (less than 1 percent) are considered to have the severe form of hemophilia. Severe hemophilia can result in frequent bleeding episodes. In many cases, bleeding occurs spontaneously into joints.
- Moderate: Factor levels of 2–5 percent are considered to have moderate hemophilia. These individuals may have abnormal bleeding after minor trauma or surgery, but rarely experience spontaneous bleeding.
- Mild: Individuals with greater than 6 percent of factor activity are considered to have mild hemophilia and are expected to have relatively few problems with bleeding, except during surgery or trauma. Carrier women can have lower-than-normal plasma levels of FVIII or FIX and thus can have bleeding problems.
The clinical manifestations of hemophilia involve joint and muscle bleeding, easy bruising, and prolonged, potentially fatal bleeding after surgery. Joints and muscles are the most common sites of bleeding, however, bleeding can occur in any part of the body. Complications depend on the site of bleeding. Bleeding into the head, neck, abdomen or stomach/intestines is considered life threatening and must be treated as an emergency.
Hemophilia is treated by replacing the deficient factor. This requires intravenous infusion of the missing factor to initiate the clotting process. For patients with mild VIII deficiency, desmopressin (DDAVP) may be used to release FVIII from endothelial cells and increase the circulating FVIII level enough to stop bleeding. This product is administered either by intravenous infusion or as a nasal spray. Specific factor replacement products, doses and additional drugs depend on the deficiency and the site and severity of the bleeding.
General healthcare recommendations
- Get an annual comprehensive checkup at a hemophilia treatment center.
- Get vaccinated. Hepatitis A and B are preventable.
- Treat bleeds early and adequately.
- Exercise to protect your joints.
- Get tested regularly for blood-borne infections.