Considering the central position of FXa in the coagulation cascade18 and that FXa acting via PARs influences inflammation and thrombosis by activating a wide range of cell types including EC19, we hypothesized that polyclonal IgG with FXa reactivity may alter these cellular actions in patients with APS and/or SLE. The gene discussed is F10; the disease is autoimmune polyendocrinopathy.