Vitamin K dependent clotting factors of hepatic origin are all of the following except: March 2007 and 2011; March 2013
**Core Concept**
Vitamin K dependent clotting factors are a group of proteins essential for blood coagulation, synthesized in the liver and dependent on Vitamin K for their gamma-carboxylation and activation. These factors play a critical role in the coagulation cascade.
**Why the Correct Answer is Right**
The correct answer is a Vitamin K dependent clotting factor that is not of hepatic origin. Among these factors, Factor VII is synthesized in the liver, whereas Factor IX is primarily produced in the endothelial cells of blood vessels, not in the liver. The gamma-carboxylation of these proteins, essential for their activation, occurs in the liver for Factor VII, but not for Factor IX.
**Why Each Wrong Option is Incorrect**
**Option A:** Factor VII - This factor is indeed synthesized in the liver and is Vitamin K dependent.
**Option B:** Factor IX - Although Factor IX is Vitamin K dependent, it is not primarily synthesized in the liver but in endothelial cells.
**Option C:** Factor X - This factor is also synthesized in the liver and is Vitamin K dependent.
**Option D:** Prothrombin (Factor II) - This factor is synthesized in the liver and is Vitamin K dependent.
**Clinical Pearl / High-Yield Fact**
It is essential to remember that Vitamin K dependent clotting factors are synthesized in the liver, except for Factor IX, which is primarily produced in endothelial cells. This differentiation is crucial for understanding the pathophysiology of bleeding disorders.
**Correct Answer: B. Factor IX**