Hereditary angioneurotic edema: Review of the literature

Congenital C1-inhibitor deficiency, or hereditary angioneurotic edema (HAE) , is a rare autosomal dominant disease due to alterations in the C1 inhibit or gene that results in a deficiency of antigenic and/or functional C1- INH . Affected patients are heterozygous, and their deficiency is incomplete, m any of them having up to 20% of the normal amount of the inhibitor. The dis ease is characterised by recurrent, circumscribed, non-pitting, and non-pru ritic subepithelial swellings of sudden onset, which fade during the course of 48-72 hours, but can persist up to 1 week. Lesions can be solitary or m ultiple and primarily involve the extremities, larynx, face, and bowel wall . Bradykinin is believed to be the main, but certainly not the sole, mediat or responsible for the bouts of edema in HAE. The diagnosis is suggested by family history, the lack of accompanying pruritus or urticaria, the presen ce of recurrent gastrointestinal attacks of colics, and episodes of larynge al edema. Diminished C4 concentrations during symptomatic periods are highl y suggestive for the diagnosis. Further laboratory diagnosis depends on dem onstrating a deficiency of C1-INH antigen (type I) in most kindreds, but so me kindreds have an antigenically intact but dysfunctional protein (type II ) and require a functional assay to establish the diagnosis. Prophylactic a dministration of either attenuated androgens or protease inhibitors has pro ved useful in reducing frequency or severity of attacks. Infusions of a vap our-heated C1-INH concentrate are safe and effective means of both preventi ng and treating attacks. Nevertheless, this treatment is expensive and this extract is not readily available. It is emphasised that administration of angiotensin converting enzyme inhibitors is contraindicated in patients suf fering from protease inhibitor deficiency states.