Christmas disease is due to deficiency of: September 2010: (A) Deficiency of factor IX, (B) Deficiency of factor X, (C) Deficiency of factor XI, (D) Deficiency of factor XII
Answer is A. Ans. A: Deficiency of factor IX Haemophilia B (or hemophilia B) is a blood clotting disorder caused by a mutation of the Factor IX gene, leading to a deficiency of Factor IX. It is the less common form of haemophilia, rarer than haemophilia A. It is sometimes called Christmas disease after Stephen Christmas, the first patient described with this disease