Hereditary angio‐oedema with normal C1 inhibitor in a family with affected women and men

Summary Recurrent angio‐oedema is a sign of various acquired and inherited disease entities, including hereditary angio‐oedema types I and II that result from a genetic deficiency of C1 inhibitor, and a recently described type of dominantly inherited angio‐oedema, which does not show a deficiency of C1 inhibitor. Until now, this new type of hereditary angio‐oedema, designated as hereditary angio‐oedema type III, has been assumed to be a disorder specific to females. We now describe a four‐generation family with dominantly inherited angio‐oedema and normal C1 inhibitor in which, in contrast to all previous observations, not only five female but also three male family members were clinically affected. One male patient was mainly affected following the intake of angiotensin‐converting enzyme inhibitors. Our current observation leads to new considerations about the classification of hereditary angio‐oedema with normal C1 inhibitor. Either hereditary angio‐oedema with normal C1 inhibitor can be an entity affecting females predominantly, but not exclusively; in that case, men appear to have a much reduced chance of clinical manifestations. Alternatively, our present observation of hereditary angio‐oedema with normal C1 inhibitor affecting both sexes may represent a new disease entity, presumably with a different underlying defect.