FASLG and autoimmune polyendocrinopathy: Antiphospholipid syndrome (APS) is a systemic autoimmune disease characterized by persistently elevated levels of circulating antiphospholipid antibodies (aPL), such as lupus anticoagulant (LAC), anticardiolipin antibodies (aCL), and anti–β2 glycoprotein I (aβ2GPI) antibodies.