Associated with a variety of diseases, notably systemic lupus erythematosus and other connective tissue diseases, thrombopenia, and arterial or venous thromboses; involves the presence of antibodies directed against phospholipids; cardiolipins show markedly elevated levels of anticardiolipin antibodies; present also are high levels of lupus anticoagulant; in pregnancy it can cause abortion.

Antiphospholipid syndrome, or antiphospholipid antibody syndrome (APS or APLS), is an autoimmune, hypercoagulable state caused by antiphospholipid antibodies. APS can lead to blood clots (thrombosis) in both arteries and veins, pregnancy-related complications, and other symptoms like low platelets, kidney disease, heart disease, and rash...