The clinical definition of antiphospholipid syndrome (APS) relies on the finding that individuals persistently positive for antiphospholipid antibodies (aPL), including lupus anticoagulant (LA), anti-β2 glycoprotein I (aβ2GPI), and anti-cardiolipin (aCL) antibodies. Here, FASLG is linked to autoimmune polyendocrinopathy.