To elucidate the potential role of intestinal permeability in HAE, this study investigated serum zonulin levels and evaluated their association with disease activity and psychiatric status.<h4>Patients and methods</h4>The study included 28 patients with HAE type 1 (HAE-C1INH) and 30 age- and sex-matched healthy controls. The gene discussed is HP; the disease is hereditary angioedema.