Christmas disease is treated by
**Core Concept**
Christmas disease, also known as hemophilia B, is a genetic disorder caused by a deficiency of the clotting factor IX. It affects the body's ability to form blood clots, leading to prolonged bleeding and hemorrhaging.
**Why the Correct Answer is Right**
The treatment of Christmas disease involves replacement of the deficient clotting factor IX. This is typically achieved through intravenous administration of recombinant factor IX, which helps restore the body's ability to form blood clots. The recombinant factor IX is produced through genetic engineering and is identical to the natural factor IX produced by the body.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because vitamin K is not a direct treatment for Christmas disease. While vitamin K is essential for the production of clotting factors in the liver, it does not replace the deficient factor IX in hemophilia B.
**Option B:** This option is incorrect because platelet transfusions are not a treatment for Christmas disease. Platelets are involved in blood clotting, but they do not replace the deficient clotting factor IX in hemophilia B.
**Option C:** This option is incorrect because antifibrinolytic agents, such as tranexamic acid, are used to prevent excessive bleeding in patients with hemophilia but do not replace the deficient clotting factor IX.
**Clinical Pearl / High-Yield Fact**
Christmas disease is an X-linked recessive disorder, meaning it primarily affects males who have only one X chromosome. Females can be carriers of the disease, but they are usually asymptomatic or have mild symptoms.
**Correct Answer: D. Recombinant factor IX.