Hereditary angio-oedema in Denmark: a nationwide survey

Background Hereditary angio-oedema (HAE) is a rare disease caused by deficiency of complement C1 inhibitor (C1 inhibitor). The diagnosis is challenging as the disease can have a variety of clinical manifestations. In 2001 a national HAE comprehensive care centre was established and a search for these patients was initiated. Objectives To identify and characterize all patients with HAE in Denmark and increase awareness of the disease. Methods Patients were recruited from hospital departments, dermatologists in private practice, Centres for Rare Diseases, the Danish patient organization and the national reference laboratory. Family interviews were conducted and medical records were evaluated. Information was spread through lectures, articles in popular magazines and via television. National guidelines for diagnosis and treatment were published. Results Eighty-two patients were identified. The mean diagnostic delay was 16.3 years. Five patients had HAE type II. Forty-five patients reported a characteristic serpiginous rash (erythema marginatum). More than 90% of patients had noticed precipitating factors before skin and mucosal swellings. Four patients underwent a total of eight tracheotomies and five families recalled 11 relatives who died of HAE. Conclusions The minimal prevalence of HAE in Denmark is similar to 1.41 per 100 000 inhabitants. The risk of upper airway obstruction underlines the importance of diagnosing these patients. Precipitating factors, a preceding or concomitant serpiginous erythema and cutaneous swelling and/or abdominal pain attack and/or laryngeal oedema are clues to the diagnosis. As a consequence of this survey, information has been spread to patients, families and physicians.