The targeting of these PF4 complexes by immunoglobulin G (IgG) antibodies underlies anti‐PF4 disorders such as heparin‐induced thrombocytopenia (HIT) and Vaccine‐Induced Immune Thrombocytopenia and Thrombosis (VITT)/VITT‐like disorders. The gene discussed is PF4; the disease is autoimmune thrombocytopenic purpura.