Antiphospholipid syndrome (APS) can be a primary disorder or secondary to an autoimmune disease such as SLE.1 2 Thrombotic APS can present with arterial, venous or microvascular thrombosis in the setting of persistently positive antiphospholipid (aPL) antibodies.3 There are three types of aPL antibodies that can be measured in routine clinical practice. The gene discussed is FASLG; the disease is antiphospholipid syndrome.