However, due to the persistence of thrombocytopenia and despite no progression of the thrombotic event, testing for anti-PF4/heparin IgG antibodies was performed using an enzyme-linked immunosorbent assay (ELISA), which returned strongly positive with an optical density (OD) of 2.8 (positivity threshold: 0.50), using the Asserachrom HPIA IgG kit (Diagnostica Stago, Asnières-sur-Seine, France). The gene discussed is PF4; the disease is Thrombocytopenia.