VITT has clinical and serological similarities to heparin-induced thrombocytopenia (thrombosis) (HIT(T)), an autoimmune disorder caused by autoantibodies against PF4 after exposure to heparin, which is also a polyanionic molecule that can form large complexes with PF4 in vitro [12,14,15]. Here, PF4 is linked to deep vein thrombosis.