Point mutations of antithrombin, C1 inhibitor, alpha(1)-antichymotrypsin, and heparin cofactor II cause a similar conformational transition, resulting in a plasma deficiency that is associated with thrombosis, angioedema, and emphysema.
The consequent lack of plasma antithrombin, C1-inhibitor and alpha(1)-antichymotrypsin results in thrombosis, angio-oedema and emphysema, respectively.
Loop-sheet polymerization is now recognized to underlie deficiency variants of other members of the serine proteinase inhibitor (serpin) superfamily, i.e. antithrombin, C1 esterase inhibitor and alpha(1)-antichymotrypsin, which are associated with thrombosis, angio-oedema and emphysema respectively.