1XX9, 1XXD, 1XXF, 1ZHM, 1ZHP, 1ZHR, 1ZJD, 1ZLR, 1ZMJ, 1ZML, 1ZMN, 1ZOM, 1ZPB, 1ZPC, 1ZPZ, 1ZRK, 1ZSJ, 1ZSK, 1ZSL, 1ZTJ, 1ZTK, 1ZTL, 2F83, 2FDA, 2J8J, 2J8L, 3BG8, 3SOR, 3SOS, 4CR5, 4CR9, 4CRA, 4CRB, 4CRC, 4CRD, 4CRE, 4CRF, 4CRG, 4NA7, 4NA8, 4TY6, 4TY7, 4WXI, 4X6M, 4X6N, 4X6O, 4X6P, 4Y8X, 4Y8Y, 4Y8Z, 4D7F, 5E2O, 5E2P, 4D76, 4D7G, 5EXL, 5I25, 5EXM, 5EOD, 5EXN, 5EOK2160109821ENSG00000088926ENSMUSG00000031645P03951Q91Y47NM_000128NM_019559NM_001354804NM_028066NP_000119NP_001341733NP_082342Factor XI, or plasma thromboplastin antecedent, is the zymogen form of factor XIa, one of the enzymes involved in coagulation.

Activation by thrombin or factor XIIa is achieved by cleavage of Arg369-Ile370 peptide bonds on both subunits of the dimer.

[11] Deficiency of factor XI causes the rare hemophilia C; this mainly occurs in Ashkenazi Jews and is believed to affect approximately 8% of that population.

[12] Low levels of factor XI also occur in many other disease states, including Noonan syndrome.

The idea behind producing such an inhibitor is that XI is mostly involved in intrinsic/contact activation pathway,[15] which plays a bigger role in thrombosis as opposed to hemostasis, so targeting it may reduce clotting risks without a corresponding increase in bleeding.