All are Vitamin K dependent clotting factors
**Core Concept**
Vitamin K-dependent clotting factors are proteins involved in the coagulation cascade that require vitamin K for their synthesis. These factors are essential for the formation of thrombin and the subsequent clotting of blood.
**Why the Correct Answer is Right**
The vitamin K-dependent clotting factors are crucial for the activation of the coagulation cascade. They include factors II (prothrombin), VII, IX, and X. These factors are produced in the liver and require vitamin K for their gamma-carboxylation, allowing them to bind to phospholipid surfaces and facilitate the coagulation process. The absence or deficiency of these factors can lead to bleeding disorders such as hemophilia.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because factor VIII is a vitamin K-independent clotting factor, which is crucial for the activation of factor X in the intrinsic pathway of coagulation. Its deficiency is responsible for hemophilia A.
**Option B:** This option is incorrect because factor V is also a vitamin K-independent clotting factor, which serves as a cofactor for the activation of factor X in the prothrombinase complex. Its deficiency can lead to bleeding disorders.
**Option C:** This option is incorrect because factor XI is a vitamin K-independent clotting factor, which is involved in the intrinsic pathway of coagulation. Its deficiency can lead to bleeding disorders, particularly in individuals with a family history of bleeding.
**Option D:** This option is incorrect because factor XIII is a transglutaminase that stabilizes blood clots, but it is not a vitamin K-dependent clotting factor.
**Clinical Pearl / High-Yield Fact**
Vitamin K-dependent clotting factors are essential for the coagulation cascade, and their deficiency can lead to bleeding disorders. These factors are also sensitive to warfarin, a commonly used anticoagulant that inhibits vitamin K epoxide reductase.
**Correct Answer:** D. Factor XIII is not a vitamin K-dependent clotting factor.