Clotting factor is deficient in hemophilia B?
Ans. d (IX). (Ref. Robbins, Pathology, 7th, 656)FACTOR IX DEFICIENCY--HEMOPHILIA B/ CHRISTMAS DISEASE# Factor IX gene is on the X chromosome.# Factor IX is a single-chain, 55-kDa proenzyme that is converted to an active protease (IXa) by factor XIa or by the tissue factor-VIIa complex.# Factor IXa then activates factor X in conjunction with activated factor VIII.# Factor IX is one of six proteins synthesized in the liver that require vitamin K for biologic activity.# Vitamin K is a cofactor for a unique posttranslational modification that inserts a second carboxyl group onto certain glutamic acid residues on factor IX.# Factor IX deficiency or dysfunction (hemophilia B) occurs in 1 in 100,000 male births.# Rx:- Either FFP or a plasma fraction enriched in the prothrombin complex proteins is used.- Monoclonally purified or recombinant factor IX preparations are now available.- In addition to the expected complications of hepatitis, chronic liver disease, and AIDS, the therapy of factor IX deficiency has a special hazard.- The recombinant or monoclonally purified products are less likely to be thrombogenic.DDAVP is a synthetic vasopressin analogue that causes a transient rise in FVIII and vWF, but not F-IX.The treatment of FXI deficiency is based on the infusion of FFP at doses of 15-20 mL/kg to maintain trough levels ranging from 10 to 20%. Because FXI has a half-life of 40-70 h, the replacement therapy can be given on alternate days. The use of antifibrinolytic drugs is beneficial to control bleeds, with the exception of hematuria or bleeds in the bladder.# Rx of Hemophilia A:- Factor replacement therapy for hemophilia can be provided either in response to a bleeding episode or as a prophylactic treatment.- Cryoprecipitate is enriched with FVIII protein (each bag contains ~80 IU of FVIII) and was commonly used for the treatment of hemophilia; but because of the risk of bloodborne diseases, it should be avoided in hemophilia patients when factor concentrates are available.# The FVIII half-life of 8-12 h requires injections twice a day to maintain therapeutic levels,# Whereas the FIX half-life is longer, ~24 h, so that once-a-day injection is sufficient.
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