The antiphospholipid syndrome (APS) is an autoantibody-mediated autoimmune disorder in which thrombosis occur in patients having laboratory evidence for so-called antiphospholipid antibodies (APL). The association of thrombosis, recurrent foetal losses and thrombocytopenia with the lupus anticoagulant (LA) phenomenon was observed forty years ago (1,2,3,4,5,6), but it was not until eighties that Hughes referred to the possible existence of a syndrome (7,8). The name of anticardiolipin syndrome was soon replaced by APS (9) known also as Hughes's syndrome. A wide spectrum of clinical and basic science disciplines has made important contributions to the knowledge of APS: immunology, rheumatology, obstetrics, neurology, haematology, molecular biology, lipid and protein chemistry etc.
Clinical and laboratory criteriaCriteria for the classification of the APS raised after many international multidisciplinary symposia and workshops and included clinical and laboratory findings (10). Definite APS is considered to be present if at least one of the clinical and one of the laboratory criteria are met (Table 1).