Hereditary angioedema (HAE) [5 genes]

Hereditary angioedema is an inflammatory disorder characterized by recurrent and unpredictable attacks of tissue swelling, which is caused by mutations in the SERPING1 (HAE types I, II) or in the F12 gene (HAE type III). SERPING1 encodes the C1 inhibitor protein, a key plasma inhibitor of the complement, the fibrinolytic and the contact pathways. In the contact pathway, it blocks the activity of the contact system enzymes, which promote inflammation. When there is not enough functional C1 inhibitor, the kallikrein-kinin pathway (contact pathway) is affected; therefore, bradykinin production is unchecked. Bradykinin promotes inflammation by increasing the leakage of fluid through the walls of blood vessels into body tissues. An excess of bradykinin leads to an abnormal tissue accumulation of fluids and episodes of swelling. In the same way, mutations in the F12 gene will have the same effect, since the coagulation factor XII also regulates bradykinin production in the contact pathway.

• Multisystemic edema
• Digestive problems
• Breathing difficulties
• Erythema marginatum (30%)
• No thrombotic events
• Onset: childhood

1:10,000 – 1:150,000

• Diagnosis and genetic counseling
• Subcutaneous icatibant
• Intravenous administration of C1-inhibitor concentrate
• Prophylaxis with tranexamic acid or attenuated androgens
• Corticosteroids, antihistamines or adrenaline treatments are not effective