Tom, a 16 years-old student, has had frequent swelling of the lips and tongue over the past few years.  Over last several days, and do not include symptoms of itchy hives with swelling, although he does occasionally suffer from nausea and abdominal pain that requires urgent treatment at the ER.  Laboratory results reveal both his C4 and C1 inhibitors are low.  Patient history also reveals that Tom’s father suffered similar episodes when he was young.

Hereditary Angioedema (HAE) is a very rare hereditary and potentially life-threatening condition that occurs in 1 of 50,000 people.  HAE is characterized by recurrent episodes of severe swelling (angioedema) of the face, hands and feet, upper airway, and intestinal tract.  Swelling involving the intestinal tract results in severe abdominal pain, nausea, and vomiting.  Swelling in the upper airway can lead to life-threatening obstruction of the airway and severely restrict breathing.  Minor trauma, surgery, illness, hormone change, or stress may trigger an attack, but swelling often occurs without a known trigger.  On average, untreated individuals have an attack every 1 to 2 weeks, and most episodes last for about 3 to 4 days.  However, the frequency and duration of attacks can vary greatly.  Since patients with HAE do not have itchy hives commonly seen in other allergic reactions, anti-histamine and corticosteroid treatments for allergies do not work.

Gene mutations cause hereditary angioedema Type I, leading to low levels of C1 inhibitor in the blood, and account for 85% of all cases.   Mutations that cause Type II result in the production of an abnormally functioning C1 inhibitor and account for the remaining 15% of cases. Without proper levels of functional C1 inhibitor, excessive amounts of specific protein peptides called kallikrein and bradykinin are generated.  Bradykinin is an inflammatory mediator that can cause the dilation of blood vessels.  Excessive bradykinin can quickly trigger the leakage of fluid through blood vessel walls into body tissues and cause the swelling typical of HAE.  Children have a 50% chance of inheriting HAE if one parent has the condition.  Yet there are patients who develop the gene mutation without a family history of HAE.

In the past few years, treatment of HAE has advanced to include several options designed to prevent and treat acute attacks.  Patients can receive treatment intravenously or even inject themselves with medication as soon as the symptoms of an acute HAE attack are apparent.  Several products of C1 inhibitor concentrate include Berinert, Cinryze, Haegarda, and Ruconest as well as Firazyr (B2 bradykinin receptor antagonist), and Kalbior (Kallikrein inhibitor).  Even though Hereditary Angioedema is a severe and potentially life-threatening medical condition, recently developed treatment options give reason for sufferers to be optimistic.