Factor VII activating protease (FSAP) is not essential in the pathophysiology of angioedema in patients with C1 inhibitor deficiency.

Background: Excessive bradykinin (BK) generation from high molecular weight kininogen (HK) by plasma kallikrein (PK) due to lack of protease inhibition is central to the pathophysiology of hereditary angioedema (HAE). Inadequate protease inhibition may contribute to HAE through a number of plasma proteases including factor VII activating protease (FSAP) that can also cleave HK.

Objective: To investigate the interaction between FSAP and C1 inhibitor (C1Inh) and evaluate the potential role of FSAP in HAE with C1Inh deficiency.