Congenital antithrombin deficiency in patients with splanchnic vein thrombosis

Abstract

Splanchnic vein thromboses (SVT) are a rare condition that can be life-threatening. The most severe thrombophilia associated to SVT is antithrombin (AT) deficiency, usually caused by SERPINC1 mutations. Although transitory AT deficiencies and congenital disorders of the N-glycosylation pathways (CDG) have been recently reported as causes of AT deficiency, the current AT clinical screening still only includes anti-FXa activity. This study aims to 1) improve the detection of antithrombin deficiency in SVT and 2) characterize the features of antithrombin deficiency associated with SVT.The study was performed in 2 cohorts: 1) 89 SVT patients with different underlying etiologies but in whom AT deficiency had been ruled out by classical diagnostic methods; and 2) 271 unrelated patients with confirmed AT deficiency and venous thrombosis. Antithrombin was evaluated by functional (anti-FXa and anti-FIIa) and immunological methods (ELISA, crossed immunoelectrophoresis, western blot), and SERPINC1 sequencing was performed.In 4/89 patients (4.5%) additional alterations in AT were found (two had SERPINC1 mutations, one had a specific variant causing transient AT deficiency and one patient had CDG). In 11 of the 271 patients (4.1%) with AT deficiency and thrombosis, thrombosis was located at the splanchnic venous territory.AT deficiency may be underdiagnosed by current clinical screening techniques. Therefore, a comprehensive AT evaluation should be considered in cases of rethrombosis or doubtful interpretation of anti-FXa activity levels. SVT is a relatively common localization of the thrombotic event in patients with congenital AT deficiency.© 2019 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.