Hageman factor deficiency

Hageman Factor Deficiency

Hageman factor deficiency, also known as Factor XII deficiency, is a rare genetic disorder that affects the blood coagulation process. It is named after John Hageman, the first patient in whom the deficiency was identified. Despite its role in the coagulation cascade, Hageman factor deficiency is usually asymptomatic and does not typically lead to bleeding disorders.

Pathophysiology

Hageman factor, or Factor XII, is a plasma protein that plays a crucial role in the initiation of the intrinsic pathway of the coagulation cascade. It is activated upon contact with negatively charged surfaces, such as glass or collagen, and subsequently activates Factor XI, leading to a cascade of reactions that result in the formation of a blood clot.

In individuals with Hageman factor deficiency, there is a deficiency or dysfunction of Factor XII. Despite this deficiency, affected individuals do not usually experience abnormal bleeding. This is because Factor XII is not essential for hemostasis in vivo, and other pathways can compensate for its absence.

Diagnosis

Hageman factor deficiency is often discovered incidentally during routine blood tests, as it is characterized by a prolonged activated partial thromboplastin time (aPTT) with normal prothrombin time (PT) and bleeding time. The diagnosis is confirmed by specific assays that measure Factor XII activity in the blood.

Clinical Significance

Although Hageman factor deficiency does not typically cause bleeding, it has been associated with an increased risk of thrombosis in some studies. The exact mechanism behind this paradoxical association is not well understood, but it is thought that the deficiency may affect other pathways involved in fibrinolysis and inflammation.

Management

Since Hageman factor deficiency is usually asymptomatic, no specific treatment is required. However, in cases where thrombosis is a concern, anticoagulant therapy may be considered. It is important for individuals with this deficiency to inform their healthcare providers, especially before undergoing surgical procedures.

Also see

• Coagulation
• Hemophilia
• Thrombosis
• Blood clotting disorders