Hereditary angioedema due to C1 inhibitor deficiency: patient registry and approach to the prevalence in Spain.

Background: Hereditary angioedema (HAE) is a rare disease caused by C1 inhibitor mutations. Although more than 100 mutations have been described, epidemiologic data are lacking; therefore, we developed a Spanish HAE patient registry.

Objective: To study the prevalence of HAE and the current state of diagnosis and treatment of this disease in Spain.

Methods: Epidemiologic data were obtained by direct contact with physicians who treat patients with HAE and with patients themselves. Diagnosis was evaluated by measuring C1 inhibitor levels and function, and most families also underwent genetic studies.

Results: We registered 444 patients (minimal prevalence, 1.09 per 100,000 inhabitants), many of whom are asymptomatic (never having symptoms) (n = 61, 13.7%). Most symptomatic patients (62.9%) receive long-term prophylaxis with attenuated androgens (80.9%) and antifibrinolytic agents (22.8%), alone or in combination, but no patients are receiving long-term prophylaxis with C1 inhibitor. There is a long delay in diagnosis (mean, 13.1 years). Nine patients underwent a tracheotomy as a consequence of a laryngeal attack, and 30 families recalled a total of 38 relatives who died of HAE, which underlines the severity of the illness.

Conclusions: The detected minimal prevalence of HAE in Spain is 1.09 per 100,000 inhabitants. Because this is a rare disease and some patients may be misdiagnosed, this prevalence could be higher.