C1-esterase inhibitor

The human C1 esterase inhibitor gene is located on the eleventh chromosome (11q11-q13.1). Deficiency of the C1 esterase inhibitor leads to activation of the complement system, which in turn leads to low plasma concentrations of complement factor C2. It is currently believed that cleaved C2 increases the permeability of vascular walls. Furthermore, it has long been hypothesized that inhibitor deficiency results in increased kallikrein and, consequently, increased bradykinin, which causes the subcutaneous swelling seen in typeI hereditary angioedema. Elevated levels of bradykinin have been noted in acute swellings.

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2. Levy JH et al (2006) The therapeutic potential of a kallikrein inhibitor for treating hereditary angioedema. Expert Opinion Investig Drugs 15: 1077-1090