Rare bleeding disorders.

Rare bleeding disorders (RBDs) include the inherited deficiencies of fibrinogen, factor (F)II, FV, FV+FVIII, FVII, FX, FXI and FXIII. There have been remarkable advances in understanding the molecular profiles that lead to each type of coagulation factor deficiency. However, as a consequence of their rarity, clinical data regarding the characteristics of bleeding symptoms and their management remain limited. The clinical manifestations in different RBDs are heterogeneous, and the residual plasma coagulant factor level does not always predict bleeding tendency. In this review, we describe the general features and recent advances in understanding three such deficiencies: FXI, FVII and fibrinogen deficiencies.