C1-INH defect as an example of deficiency disease.

Primary defect of C1-inhibitor (C1-INH), the regulatory protein of the initial classical pathway of complement, is the cause of hereditary angioedema. Clinical symptoms involve potentially fatal obstruction of the upper respiratory tract, abdominal pains, and subcutaneous edemas. Since the description of functional tests for C1-INH two types of hereditary defect have been known: type I and type II. Sixteen patients with the type I of hereditary angioedema were diagnosed and treated in our hospital. The onset of the disease occurred between 1.5-12 y. of age. Clinical symptoms were observed in skin, gastrointestinal and respiratory tracts. Mean concentration of C1-INH in sera of 16 patients was 3.25 mg/dl, below 8.75 mg/dl that is the critical for well-functioning C1-INH. Inhibitory activity of C1-INH for C1 esterase in plasma was zero in most of the patients, while it was 0.94 +/- 0.20 U/ml in plasma samples of 91 healthy blood donors. Three modalities of treatment are available: substitution with C1-INH concentrate in acute attacks and antifibrinolytic and/or anabolic drugs for prophylaxis. We have obtained good therapeutic results with epsilon-aminocaproic acid (antifibrinolytic), 2g daily during 3 months, with 6 months intervals.