Hereditary Angioedema is a rare genetic condition that causes episodes of edema (swelling) in various parts of the body intermittently. The main target areas are usually limbs, throat, lips, eyelids and abdomen. These attacks may or may not occur frequently. But if left untreated, it can be life-threatening. However, the patient feels completely normal in between the attacks. This condition occurs as result of either deficiency or improper function of protein C1 esterase inhibitor (C1-INH) in plasma. C1 esterase inhibitor is responsible for regulating the production of a hormone called bradykinin. Higher amount of bradykinin is produced in the body when protein C1 esterase inhibitor does not function normally. Increased bradykinin hormone levels leak the fluid from blood vessels into the body tissues resulting in edema.
There are three different types of Hereditary Angioedema.
In Type I HAE, blood contains low level of C1 esterase leading to excess production of bradykinin, resulting in swelling attack.
With Type II HAE, blood contains normal levels of protein C1 esterase inhibitor but fails to function normally leading to to inflammation and swelling episodes.
Type III HAE is very rare, and isn't associated with functioning of C1 esterase inhibitor.
HAE is caused due to the mutations inherited from a parent. The gene is dominant, which means one abnormal copy is enough to cause HAE. However, one fourth of the Hereditary angioedema cases aren't inherited. They occur from spontaneous mutation that takes place at conception.
Symptoms of Hereditary Angioedema
Most often Hereditary Angioedema manifests into cutaneous swelling, on the face, hands and extremities. Though not common, it also causes abdominal swelling and the swelling of airway passage in few cases. The disease may become potentially life-threatening when upper respiratory system of the patient is attacked - asphyxiation. Early suspicion, recognition and treatment of this condition are important.
Certain triggers have been identified that leads to the episodes of swelling. Try and identify your triggers - certain foods, environmental factors, medications, anxiety or certain physical activities. They include physical injury, medical or dental procedures, psychological stress, menstruation, pregnancy, infections and certain medications such as exogenous estrogen (OCP) and angiotensin-converting enzyme inhibitors. Some patients do take preventive medication, after consulting their doctor. After a bout of HAE, take rest and hydrate yourself. Log your attacks.
Diagnosis and treatment
Since edema can indicate host of other conditions, it is difficult to diagnose HAE with clinical symptoms alone. Taking note of family history of swelling attacks and the frequency of attacks in the patient himself should be the starting point to diagnosis. Further, laboratory analysis of blood samples for C1, C2 and C4 levels along with genetic testing is required to confirm Hereditary Angioedema.
Currently there is no cure for Hereditary angioedema. However medicines are available for treating patients with acute HAE attacks to address the symptoms during attacks. HAE is also treated with prophylactic therapy (preventative HAE treatment).
Bibliography / Reference
Collection of Pages - Last revised Date: March 20, 2019