Thrombotic complications in HLH, including deep vein thrombosis and myocardial infarction, arise from endothelial injury mediated by tissue factor and vascular endothelial growth factor (VEGF) upregulation, alongside neutrophil extracellular trap (NET)-driven microthrombosis [67,68,69]. The gene discussed is VEGFA; the disease is deep vein thrombosis.