Genetic test indications and interpretations in patients with hereditary angioedema.

Patients with hereditary angioedema (HAE) present with recurrent, circumscribed, and self-limiting episodes of tissue or mucous membrane swelling caused by C1-inhibitor (CI-INH) deficiency. The estimated frequency of HAE is 1:50,000 persons. Distinguishing HAE from acquired angioedema (AAE) facilitates therapeutic interventions and family planning or testing. Patients with HAE benefit from treatment with attenuated androgen, antifibrinolytic agents, and C1-INH concentrate replacement during acute attacks. HAE is currently recognized as a genetic disorder with autosomal dominant transmission. Other forms of inherited angioedema that are not associated with genetic mutations have also been identified. Readily available tests are complement studies, including C4 and C1-esterase inhibitor, both antigenic and functional C1-INH. These are the most commonly used tests in the diagnosis of HAE. Analysis of C1q can help differentiate between HAE and AAE caused by C1-INH deficiency. Genetic tests would be particularly helpful in patients with no family history of angioedema, which occurs in about half of affected patients, and in patients whose C1q level is borderline and does not differentiate between HAE and AAE. Measuring autoantibodies against C1-INH also would be helpful, but the test is available in research laboratories only. Simple complement determinations are appropriate for screening and diagnosis of the disorder.

Masqueraders of angioedema and urticaria.

OBJECTIVES: Reading this article will remind the reader that some patients presenting with complaints of urticaria and angioedema may not have urticaria or angioedema at all, but may have other causes, often unusual, sometimes treatable. It will also increase the reader's ability to recognize masqueraders of angioedema, urticaria, and facial swelling thought to be angioedema. DATA SOURCES: Data for this article come mainly from the authors' personal experiences and selected references to illustrate points made in the article. STUDY SELECTION: The criteria used are patients and articles from the authors' experiences that illustrate the point of this article that patients presenting with urticaria and angioedema may have other diseases and some of these are treatable. RESULTS: The objectives will be met by patient presentations plus pertinent literature review. CONCLUSIONS: Some patients presenting as angioedema and urticaria have swelling and skin lesions attributable to other causes. Although they are uncommon, they are sometimes treatable. Not all patients referred to an allergist for angioedema have angioedema.