A possible explanation for the failureof DOACs in these settings is the direct inhibition of a single coagulationfactor compared with warfarin which blocks the production of several factors ofthe intrinsic and common pathways, including factor IX (FIX), factor X (FX), and prothrombin, inaddition to factor VII (FVII) in the extrinsic pathway, all playing a role in thethromboembolic mechanism related to mitral stenosis and mechanical prostheses. The gene discussed is F9; the disease is mitral valve stenosis.