Hemofilia B o enfermedad de Christmas

Hemophilia B or Christmas disease was first differentiated from hemophilia A in 1947. Its classic form consists of an inherited bleeding disorder caused by mutations in the F9 gene, which codes for coagulation factor IX. Its inheritance is linked to the X chromosome; women are carriers, but it manifests clinically in men, although cases of symptomatic women carriers have been described. Factor IX activates a vitamin K-dependent protein, synthesized in the liver, which is part of the tenase complex whose function is to form the largest amount of thrombin(factor IIa) in the new model of cell-based coagulation. According to factor IX activity, its deficiency can be classified as mild (5% to 40%), moderate (1% to 5%), and severe (<1%). The diagnosis is made when there is a prolonged TPT that corrects with normal plasma, and by assessing the functional level of factor IX. The diagnosis is confirmed by molecular analysis that demonstrates the F9 gene mutation. Its differential diagnosis includes disorders such as hemophilia A. Treatment with recombinant factor IX is widely used, but also new therapies are being developed with recombinant adeno-associated viruses that promise to improve the quality of life for some of these patients. Prophylaxis plays an important role in cases of moderate and severe disease.Keywords: hemophilia B, Christmas disease, factor IX, partial thr