Hereditary Anticoagulant Deficiencies

Abstract

Thromboembolisms occur as a consequence of genetic predispositions, underlying disorders, and direct triggers such as dehydration, infection, or injury. Heritable defects in the coagulant and anticoagulant pathways result in the development of venous thromboembolism (VTE) with or without apparent triggers. The genetic risks of VTE include the deficiency of anticoagulant factors of protein C (PC), protein S (PS), and antithrombin, as well as the variants of coagulation factors of factor V G1691A (factor V Leiden) and prothrombin (factor II) G20210A. Hereditary anticoagulant deficiencies are suspected in young adult VTE, neonatal purpura fulminans, patients having recurrent VTE, and/or family history of thrombosis or anticoagulant deficiencies. The hereditary anticoagulant deficiencies are difficult to diagnose in infants and young children without the genetic tests, because these activities are physiologically lower in childhood than in adulthood. Unexplained dissociation among PC, PS, and factor VII activity levels may portend a diagnosis of heritable PC or PS deficiency. The coagulation studies by using the age-dependent standards have then high sensitivity in screening for anticoagulant deficiencies. Nevertheless, repeated sampling, family studies, and genetic analyses along with the detailed information of reported cases are essential for the diagnosis for anticoagulant deficiency.