A novel C1 inhibitor gene mutation in a family with hereditary angioedema : Use of genetic analysis to facilitate early diagnosis

Dear Editor, Hereditary angioedema (HAE) is a rare autosomal dominant disorder characterized by recurrent episodes of angioedema or deep localized swelling, without urticarial rash. HAE most often affects the skin or mucosal tissues of the upper respiratory and gastrointestinal tracts, and laryngeal involvement may result in lethal asphyxiation. In most cases, HAE occurs as a result of mutations in the SERPING1 gene, which encodes the serine protease C1 inhibitor (C1-INH); HAE type I results from C1-INH deficiency, while type II is caused by C1-INH dysfunction. Here, we report a family with HAE type I carrying a novel missense mutation in SERPING1. The study protocol was approved by the Institutional Review Board of the Japanese Red Cross Wakayama Medical Center (no.548). Patient 6 was a 31-year-old male who presented following two attacks of angioedema of the extremities, lips, face, genitals, and abdomen over a 2 year period, without respiratory symptoms. The trigger for his first episode was contracting hand-foot-mouth disease in his late twenties, while the trigger for the second episode, which occurred 1 year after the first, was unknown.