Among functional antibodies, besides those targeting GPCRs, anti-endothelial cell autoantibodies (AECA) are a heterogeneous group that can bind to proteins and molecules expressed on the ECs’ surface, resulting in several pathophysiological effects, such as direct or indirect cytotoxicity, ECs apoptosis and activation with increased leukocyte adhesion, coagulation activation, vascular thrombosis, and the release of profibrotic (transforming growth factor-beta, TGF-β) and vasoactive (endothelin-1, ET-1) mediators [21]. The gene discussed is EDN1; the disease is deep vein thrombosis.