Clinical findings, a positive family history(the patient's mother died of suffocation from laryngeal edema at the age of 32),and the results of complement testing (C4: 0.02 g/L [normal 0.15 to 0.55 g/L];C1-esterase inhibitor antigenic level: 0.03 g/L [normal 0.15 to 0.3 g/L];C1-esterase inhibitor functional activity: 18% [normal 70 to 100%]; C1q: 118 mg/L[normal 60 to 180 mg/L]) confirmed the diagnosis of type I HAE. This evidence concerns the gene C1S and hereditary angioedema.