Antithrombin III deficiency: decreased synthesis of a biochemically normal molecule.
A 29-yr-old white female has suffered from recurrent venous thromboses over the last 12 yr. Plasma antithrombin III (AT-III) levels were 48% of normal by immunoelectrophoresis and 56% by chromogenic assay. Three of four siblings and the father had similar AT-III levels without associated venous thromboses. Heparin-Sepharose chromatography demonstrated normal behavior of the patient's AT-III. Her purified AT-III could not be distinguished from AT-III purified from a normal control either by SDS polyacrylamide gel electrophoresis or by crossed immunoelectrophoresis, and the heparin cofactor activity and the progressive antithrombin activity of both AT-III samples were identical. Turnover studies were made in the patient using her own purified AT-III labeled with 131I, (*I). The results did not differ significantly from studies made with autologous *I-AT-III in two normal control women. Her fractional breakdown rate of 0.54 total plasma AT-III per day compared with 0.45 and 0.52 in the controls. These studies indicate that the patient synthesizes a normal AT-III molecule at half normal rates.
D000328:Adult; D000368:Aged; D000941:Antigens / Q000032:analysis; D000990:Antithrombin III / Q000096:biosynthesis* / Q000276:immunology / Q000502:physiology; D002863:Chromogenic Compounds / Q000494:pharmacology; D005260:Female; D006801:Humans; D007123:Immunoelectrophoresis, Two-Dimensional; D008875:Middle Aged; D013918:Thrombin Time; D013924:Thrombophlebitis / Q000097:blood* / Q000175:diagnosis / Q000235:genetics
D000941:Antigens; D002863:Chromogenic Compounds; D000990:Antithrombin III