APOH (Apolipoprotein H): APOH is a multifunctional plasma protein, also known as beta-2-glycoprotein I, that plays a vital role in lipid metabolism and hemostasis. It is a key factor in antiphospholipid antibody syndrome (APS), where it helps regulate the coagulation cascade and prevent thrombosis. APOH interacts with lipoproteins, phospholipids, and coagulation factors, contributing to immune modulation and the clearance of apoptotic cells. In addition to its role in blood clotting, APOH has anti-inflammatory effects and supports endothelial function and vascular health. Dysregulation of APOH is linked to various thrombotic and vascular disorders.