The clinical resemblance of unexplainable thrombocytopenia and thrombosis to spontaneous heparin-induced thrombocytopenia (spHIT) prompted investigators to test patient serum for antibodies against platelet factor 4 (PF4/CXCL4) [13], a protein extensively studied for its role in the pathogenesis of HIT [16]. The gene discussed is PF4; the disease is Thrombocytopenia.