In patients with HES, high eosinophil count can decrease thrombomodulin level (by proteins secreted from their granules) and increase the expression of tissue factor (released from eosinophil granules) with consequent activation of factor VII and an increase in fibrinogen level [8, 9], leading to the activation of the coagulation cascade and hypercoagulability state [3]. The gene discussed is THBD; the disease is hypereosinophilic syndrome.