: Risk for thrombotic events with factor IX replacement therapy in patients with haemophilia B remains a concern for patients, those who treat them, and regulatory agencies, based on experience with early use of prothrombin complex concentrates.
Infusion of bypassing agents, such as recombinant activated FVII (rFVIIa) and plasma-derived activated prothrombin complex concentrate, are suggested as alternative therapies to factor VIII (haemophilia A) or IX (haemophilia B) for individuals who no longer respond to these treatments because they develop inhibitory antibodies.
Congenital rare bleeding disorders RBD are reported in most populations, with incidence varying from 1 in 5000 (Hemophilia A), 1:30,000 (Hemophilia B) to much rarer (1:500,000 for FVII deficiency, 1-3 million for Prothrombin or FXIII deficiency).
The different bleeding condition will be dealt with separately, namely, prothrombin or Factor II, Factor VII, Factor IX (hemophilia B), and Factor X deficiencies.
In a patient with severe hemophilia B and a markedly prolonged ox-brain prothrombin time, a C to T transition in exon VI changed the codon for Arg180 to Trp (factor IX BMNagoya 2).
The disease is characterized by a normal ox-brain prothrombin time, normal levels of the vitamin-K dependent clotting factors VII and X and a proportional reduction of factor IX activity and antigen levels all of which is consistent with the cross-reacting material negative form of haemophilia B.
Twenty three patients belonging to 18 different pedigrees of Haemophilia B were studied with regard to ox-brain prothrombin time and its correlation to factor VII.