Impaired control of the contact system in hereditary angioedema with normal C1‐inhibitor

Background Hereditary angioedema (HAE) comprises HAE with C1‐inhibitor deficiency (C1‐INH‐HAE) and HAE with normal C1‐INH activity (nl‐C1‐INH‐HAE), due to mutations in factor XII (FXII‐HAE), plasminogen (PLG‐HAE), angiopoietin 1 (ANGPT1‐HAE), kininogen 1 genes (KNG1‐HAE), or angioedema of unknown origin (U‐HAE). The Italian network for C1‐INH‐HAE (ITACA) created a registry including different forms of angioedema without wheals. Objective We...