[Hereditary angioedema biological diagnosis]

C1 inhibitor (C1 Inh) activity is an essential parameter for kinins angioedema (AE) diagnosis either hereditary or acquired or sporadic, it is analysed on plasma exclusively. Hereditary AE with C1 Inh functional deficiency is associated with alterations of the SERPING1 gene. Hereditary AE with normal C1 Inh (HAE nC1 Inh) is combined with F12 gene mutations, it is coding for Factor XII whose activity is controlled by C1 Inh, they are found in about 5% of HAE nC1 Inh cases. Every loss of C1 Inh activity must be taken as anormal by clinicians even for women with oral oestroprogestatives, it would be confirmed by the presence of cleaved C1 Inh. The kinins (primarily bradykinin) are the mediators responsible for local increase of vascular permeability. Bradykinin is released from high MW kininogen (HK) during the contact system activation. Plasma proteases mainly support this proteolytic activity controlled by C1 Inh. Family of a patient diagnosed with HAE must be studied, symptomatic as asymptomatic members indeed clinical symptoms regularly emerge very late in the life.