FASLG and autoimmune polyendocrinopathy: However, it is not unusual to find patients with clinical manifestations characteristic of APS but with persistently negative aPL tests including aCL and aβ2GPI; IgG and IgM, detected by enzyme linked immunosorbent assay (ELISA); and LA detected by clotting assays according to the guidelines of the International Society on Thrombosis and Haemostasis in daily clinical practice.