Factor XI Deficiency.

Factor XI (FXI) deficiency (hemophilia C or Rosenthal disease) was first described in the 1950s in a multigenerational family experiencing bleeding related to surgery and dental procedures. Managing patients with FXI deficiency presents several challenges, including a lack of correlation of bleeding symptoms with FXI activity levels, the large volume of fresh frozen plasma required to achieve hemostatic FXI levels, lack of availability of FXI concentrate in certain regions of the world, and the inherent thrombotic risk associated with replacement therapy. This article summarizes presentation, diagnosis, and management of patients with FXI deficiency in a variety of clinical settings.