Two patients with the congenital deficiency of antithrombin III (AT-III) assoiated with superior mesenteric venous thrombosis (SMVT) are described and a possible relevance of the AT-III deficiency to SMVT is discussed.
Patient No. 1: A 34 year-old male without a history of thrombosis was found to have SMVT at operation, which was further confirmed histologically. Hematological studies disclosed abnormally low levels of progressive antithrombin activity, heparin-cofactor as well AT-III antigen. The decreased AT-III was also found in his mother, sister and niece.
Patient No. 2: The diagnosis of SMVT was established surgically as well as histologically in a 24 year-old male, whose father had died of recurrent SMVT. Abnormally decreased levels at about 50% of normal of progressive antithrombin. heparin-cofactor and AT-III antigen were also found in this patient and his sister. The familial involvement in their family indicates that the decrease in AT-III is hereditary, most probably autosomally transmitted. Besides the decreased level of AT-III, no abnormal laboratory findings were noted in both patients and their affected family members.
Thus we suggest that the SMVT found in these patients were due to the congenital deficiecy of AT-III.