Antithrombin III (AT III) Padua2: A “New” congenital abnormality with defective heparin co-factor activities but no thrombotic disease

Abstract

A "new" antithrombin III (AT III) abnormality is described in five members of the same family. None of the affected members showed thrombotic manifestations and no consanguinity was present in the family. The main laboratory features were: normal routine clotting tests, slightly decreased AT III activities in all assays carried out in the presence of heparin. In the absence of heparin, antithrombin III activities were instead within normal limitis. Progressive AT III activity and AT III antigen were also normal. Crossed immunoelectrophoresis in the absence of heparin showed a normal pattern both in plasma and serum. In the presence of heparin, the propositi's plasma showed a major, less anodal, abnormal peak and a smaller normal peak. Three peaks were present in the propositi's serum as compared with the two normal ones. This AT III abnormality is different from AT III Padua previously described by us and we propose the toponym of Antithrombin Padua-2 to define this condition.

Antithrombin III Geneva: A Hereditary Abnormal AT III with Defective Heparin Cofactor Activity

“…3 Inhibition of thrombin and of activated factor X by normal (N) and propositus (P) plasma in absence (A) and in presence (B) of heparin minutes been described. In three of them no thromboembolic disorder was found (2,5,8). In the four other similar variants published, only one rnember per family experienced thrombosis (3,4,6,9) and moreover two were homozygous (6,9).…”

A Swedish family with abnormal antithrombin III

“…CIE of normal plasma gave 1 high, fast moving peak, followed by 2 small, slow-moving peaks Padua (15) Padua 2 (16) Toyama (17) Ann Arbor (18) Aalborg (19) Chicago (20) Vicenza (21) Milan ( position roughly corresponding to that of the 1st of the slow-moving peaks in normal plasma (Figure 1C).…”

Laboratory Diagnosis of Antithrombin and Heparin Cofactor II Deficiency

“…Nevertheless, it has been suggested that heterozygous patients with variant antithrombin molecules, particularly type III, have fewer thromboembolic complications. [46][47][48] In these families, thrombosis has occurred only in homozygous persons.…”