There are three types of hereditary angioedema. In Type I, individuals have low levels of normal C1-INH. In Type II, individuals have normal or elevated levels of C1-INH, but it does not function correctly. Type III is an estrogen-dependent form of angioedema that occurs only in women.
Individuals with hereditary angioedema may also have systemic lupus erythematosus or other autoimmune disorders.
Symptoms
Although individuals are born with hereditary angioedema, most children do not experience symptoms until puberty. The symptoms occur in episodes or attacks which often happen for no reason. Other causes of attacks may be anxiety, stress, minor injury, surgery, or illness. Some women report more attacks during their menstrual periods. Attack symptoms may include:- Before the attack:
- tightness or tingling at the site where the swelling will later occur
- flat, red blotchy rash (erythema marginatum) breaks out
- mood changes, anxiety, exhaustion
- During the attack:
- swelling of body parts such as hands, feet, face, arms, or legs
- internal swelling in abdomen may cause pain, nausea, and vomiting
- swelling of the airway may cause difficulty swallowing, change in voice pitch, or difficulty breathing
Diagnosis
Since the symptoms of hereditary angioedema may be caused by other disorders (such as an allergic reaction), blood tests or genetic tests are needed to confirm the diagnosis. Two specific blood tests for hereditary angioedema check the level of C1-INH and whether it is functioning properly. If the disorder is present, the levels of C1-INH would be low or poorly functioning. Genetic testing could look for one of the known gene defects of chromosome 11 associated with hereditary angioedema.Treatment
Medicine usually used to treat swelling, such as corticosteroids (like prednisone), antihistamines, and epinephrine are not effective in treating hereditary angioedema attacks. During an attack, C1-INH concentrate (available in Europe but not in the United States) or fresh frozen plasma (blood transfusion) may be given, as well as other medications for pain, nausea, and vomiting.If a person with hereditary angioedema has frequent attacks, preventive (prophylactic) drugs such as danazol (Danocrine) or oxandrolone (Oxandrin) may be given.
If surgery or dental work is needed, preventive medications such as C1-INH concentrate, danazol, or aminocaproic acid (Amicar) may be given prior to the procedure.
New treatments
Three types of medications are being developed to treat hereditary angioedema. One type is a kallikrein inhibitor called ecallantide (DX 88), being developed jointly by Dyax Corp and Genzyme Corp. The second type is a bradykinin receptor antagonist called Icatibant, developed by Jerini AG. The third type is C1-INH concentrate products, some of which have been available in Europe and are being developed for the U.S. market. All three types of medications increase the levels of properly functioning C1-INH in the blood.Sources:
Bas, M., J. Bier, J. Greve, G. Kojdo, & T.K. Hoffmann. "Novel pharmacotherapy of acute hereditary angioedema with bradykinin B2-receptor antagonist icatibant." Allergy 61(2008): 1490-1492.
Frank, M.M.. "Hereditary angioedema: the clinical syndrome and its management in the United States." Immunol Allergy Clin North Am 26(2006): 653-668.
"HAE Frequently Asked Questions." HAEA.org. United States Hereditary Angioedema Association. 5 Apr 2007 <http://www.haea.org/pamphlet.php>.
Heymann, Warren R., & Kathleen M. Rossy. "Hereditary Angioedema." eMedicine. 27 Feb 2006. WebMD. 5 Apr 2007 <http://www.emedicine.com/derm/topic24.htm>.
Zuraw, B.L.. "Novel therapies for hereditary angioedema." Immunol Allergy Clin North Am 26(2006): 691-708.
