Hereditary angioedema (HAE), a rare but life-threatening condition, manifests as acute attacks of facial, laryngeal, genital, or peripheral swelling or abdominal pain secondary to intra-abdominal edema. Resulting from mutations affecting C1 esterase inhibitor (C1-INH), inhibitor of the first complement system component, attacks are not histamine-mediated and do not respond to antihistamines or corticosteroids. Low awareness and resemblance to other disorders often delay diagnosis; despite availability of C1-INH replacement in some countries, no approved, safe acute attack therapy exists in the United States. The biennial C1 Esterase Inhibitor Deficiency Workshops resulted from a European initiative for better knowledge and treatment of HAE and related diseases. This supplement contains work presented at the third workshop and expanded content toward a definitive picture of angioedema in the absence of allergy. Most notably, it includes cumulative genetic investigations; multinational laboratory diagnosis recommendations; current pathogenesis hypotheses; suggested prophylaxis and acute attack treatment, including home treatment; future treatment options; and analysis of patient subpopulations, including pediatric patients and patients whose angioedema worsened during pregnancy or hormone administration. Causes and management of acquired angioedema and a new type of angioedema with normal C1-INH are also discussed. Collaborative patient and physician efforts, crucial in rare diseases, are emphasized. This supplement seeks to raise awareness and aid diagnosis of HAE, optimize treatment for all patients, and provide a platform for further research in this rare, partially understood disorder.

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Hereditary angioneurotic edema is a rare disorder caused by the congenital deficiency of C1 inhibitor. Recurring angioedematous paroxysms that most commonly involve the subcutis (eg, extremities, face, trunk, and genitals) or the submucosa (eg, intestines and larynx) are the hallmarks of hereditary angioneurotic edema. Edema formation is related to reduction or dysfunction of C1 inhibitor, and conventional therapy with antihistamines and corticosteroids is ineffective. Manifestations occur during the initial 2 decades of life, but even today there is a long delay between the onset of initial symptoms and the diagnosis of hereditary angioneurotic edema. Although a variety of reviews have been published during the last 3 decades on the general management of hereditary angioneurotic edema, little has been published regarding management of pediatric hereditary angioneurotic edema. Thus, we review our experience and published data to provide an approach to hereditary angioneurotic edema in childhood.

Hereditary angio-oedema (HAE) results from the deficiency of C1-esterase inhibitor (C1-INH). The clinical picture of this autosomal dominant disorder is characterized by recurrent attacks of subcutaneous oedema and/or potentially life-threatening swelling of the submucosa. This review discusses the authors' decade-long experience obtained in the treatment and follow-up of pediatric patients with HAE. Twenty-six children with HAE were reviewed. Pedigree analysis was performed in all cases to identify afflicted relatives. C1-INH concentrate was reserved for the emergency treatment of acute oedematous attacks, whereas tranexamic acid and danazol were administered for short- or long-term prophylaxis. Follow-up care included laboratory tests and abdominal ultrasound, which was repeated at regular intervals. Twenty-one children had Type I HAE and five suffered from Type II HAE. Clinical manifestations of the disease first occured in children when 2.5-12 years of age. Oedema formation primarily afflicted subcutaneous tissues. Mechanical trauma was identified as a precipitating factor in 20 patients. Pedigree analysis revealed 24 patients with relatives who suffered from HAE. Long-term prophylaxis with tranexamic acid or danazol was initiated in 11 patients; two children required short-term prophylaxis. No drug-related adverse effects were observed, except for one case of delayed menarche. Therapy improved serum complement parameters significantly and substantially reduced the frequency and severity of clinical episodes. Adequate prophylaxis and follow-up care can spare pediatric patients from oedematous attacks caused by HAE. Undesirable adverse effects can be avoided and the patient's quality of life enhanced considerably by administering the lowest effective drug dose.

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