Critical Update of the Antiphospholipid Syndrome Criteria

Diagnosis of Antiphospholipid Syndrome (APS) is made when vascular thrombosis or pregnancy morbidity occur in patients with circulating antiphospholipid antibodies [lupus anticoagulant (LA) and/or IgG/IgM anticardiolipin (aCL) and/or IgG/IgM anti2glycoprotein I (a 2GPI) antibodies]. Although each test may identify different autoantibodies, a single positive test makes the diagnosis possible when positive on two or more occasions at least 12 weeks apart. However, single test positivity may be unrelated to pathogenic antibodies that are now considered a subclass of a 2GPI directed to Domain I of the protein. Conversely, all the test positive identify a single class of a 2GPI antibodies and identify high risk patients with APS.