Problem: Hereditary angioedema is a rare, autosomal dominant genetic disorder that is characterized by painful, unpredictable, and potentially fatal attacks of swelling primarily in the gastrointestinal tract and cutaneous and submucosal tissues of the body. Symptoms often first appear during childhood, with attacks occurring in patients throughout their lifetime. Angioedema attacks may occur as frequently as every several days1 and can last from a few hours to several days2; laryngeal edema can be life-threatening because it may result in airway obstruction and death by asphyxiation.3,4 The symptoms of hereditary angioedema result from the dysregulation of the contact activation pathway. C1 esterase inhibitor (C1-INH) is a key regulator of the pathway and attenuates the production of bradykinin, a peptide that leads to increased vascular permeability and subsequent tissue swelling, by means of the inhibition of the proteases factor XIIa and plasma kallikrein. In the most common types of hereditary angioedema, C1-INH deficiency (in type 1 disease) and C1-INH dysfunction (in type 2 disease) lead to increased bradykinin production and angioedema attacks. Need Assignment Help?