Background: Antiphospholipid antibody syndrome (APS) can either occur as a primary syndrome or associated with other autoimmune diseases such as systemic lupus erythematosus (SLE). Anticardiolipin antibody (aCL) of IgG and/or IgM isotype in blood, measured by a standardized ELISA is the most acceptable laboratory criteria. APS IgG isotype, particularly IgG2 subclass is more strongly associated ...