Factor IX deficiency results in increased
**Core Concept**
Factor IX deficiency, also known as hemophilia B, is a bleeding disorder caused by a deficiency or dysfunction of the clotting factor IX. This factor plays a crucial role in the intrinsic pathway of blood coagulation, specifically in the conversion of factor X to factor Xa.
**Why the Correct Answer is Right**
The intrinsic pathway of blood coagulation is activated when blood comes into contact with a negatively charged surface, such as glass. Factor IX, along with factor XI, is activated to factor IXa by factor XIa. Factor IXa then activates factor X to factor Xa, which eventually leads to the formation of a blood clot. A deficiency of factor IX leads to impaired clot formation, resulting in increased bleeding tendency.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because factor IX deficiency does not result in increased levels of factor IX. Instead, the levels of factor IX are decreased, leading to impaired clot formation.
**Option B:** This option is incorrect because factor IX deficiency does not result in increased levels of platelets. Platelets are involved in the initial step of clot formation, but factor IX plays a crucial role in the intrinsic pathway of blood coagulation.
**Option C:** This option is incorrect because factor IX deficiency does not result in increased levels of von Willebrand factor (vWF). vWF is a protein that helps to stabilize factor VIII and is involved in platelet adhesion to the site of injury.
**Clinical Pearl / High-Yield Fact**
Factor IX deficiency is an X-linked recessive disorder, which means that it predominantly affects males. Females can be carriers of the disorder, and in rare cases, they may exhibit mild symptoms.
**Correct Answer:** C. Increased bleeding tendency.