PROS1 and hyperinsulinemic hypoglycemia, familial, 4: Regarding the initial laboratory workup, before plasmapheresis or rituximab infusions, antiphospholipid antibodies were negative (LA, aCL and β2GPI) as well as screening for thrombophilia (including protein C and protein S deficiency, antithrombin III deficiency, Leiden Factor V mutation and prothrombin mutations), and other autoimmune diseases.