APOH (apolipoprotein H), also known as β2-glycoprotein I, is a plasma lipoprotein that functions primarily in hemostasis and complement regulation. It binds negatively charged substances including heparin, phospholipids, and dextran sulfate, and may prevent activation of the intrinsic blood coagulation cascade by binding to phospholipids on damaged cell surfaces 1. APOH is a component of high-density lipoprotein (HDL) particles and regulates the activity of proteins involved in lipid metabolism and the endogenous coagulation cascade 1. Mechanistically, APOH influences lipoprotein(a) [Lp(a)] levels as a novel genetic locus independent of LPA itself 23. The APOH variant rs8178824 is associated with increased Lp(a) levels and demonstrates stronger effects after accounting for LPA variation 2. APOH is also involved in lipid metabolism reprogramming, with reduced expression correlating with colorectal cancer progression through the NR1D1/APOH signaling axis 4. Clinically, APOH variants are associated with antiphospholipid syndrome (APS) and recurrent pregnancy loss, with specific polymorphisms (rs1801690, rs52797880, rs8178847) showing significant differences in APS and RPL patients 5. APOH-containing exosomes impair vascular development and contribute to APS pathogenesis 6. Additionally, low plasma APOH levels are associated with worse prognosis in severe influenza infection, including respiratory failure 7. APOH also shows associations with nonalcoholic fatty liver disease susceptibility 8.