This cluster of papers focuses on the molecular mechanisms, pathophysiological consequences, and clinical management of Hereditary Angioedema. It covers topics such as the role of kinin receptors, coagulation factors XII and XI, polyphosphate, C1 inhibitor deficiency, and the use of bradykinin-receptor antagonists in the treatment of angioedema. Additionally, it explores the involvement of tissue kallikreins and the contact activation system in the disease pathology.