[National prevalence survey of hereditary angioedema in Japan]

The prevalence of hereditary angioedema (HAE) is estimated to be approximately 1 case per 50000 persons in English literatures. However, neither disease prevalence nor epidemiologic features of HAE has been surveyed in Japan.

A nation-wide prevalence survey of HAE in Japan was conducted in 2009. We mailed questionnaires to hospitals with 200 or more beds (1389 hospitals and 5240 departments including Dermatology, Otolaryngology, Emergency Medical Care, Internal Medicine, Pulmonary Medicine, Allergy & Rheumatology), to ask numbers, disease types, symptoms and treatments of angioedema of patients visited to their hospitals.

In total, 1128 replies were obtained and 411 patients of angioedema including 52 HAE type1 or type2 patients were reported. In the HAE type1 or type2 patients, 54% patients have experienced cutaneous swelling on face, 42% patients have experienced throat discomfort and 37% had experienced abdominal symptoms. In acute attacks of HAE, 29% patients had been treated with C1-inhibitor concentrates.

The prevalence of HAE in Japan may be lower than the estimated prevalence mainly in Europe and North America. Many patients with HAE may not be appropriately treated especially for their acute attacks. Further studies by genomic analysis should be performed to reveal the penetrance of the C1 inhibitor gene deficiency and occurrence of HAE type3 in Japan.