ABO blood group in primary antiphospholipid syndrome: influence in the site of thrombosis?

Antiphospholipid syndrome (APS) is characterized by vascular thrombosis and/or obstetric complications associated with presence of antiphospholipid antibodies (aPL) but additional factors would also induce thrombosis. ABO (H) blood groups are known to be closely related to thrombosis, especially non-O blood type with venous events. The aim of this study was to investigate possible role of ABO (H) blood types in the thrombotic events in primary APS (PAPS).