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Question #46391
The Question
A patient with no family history of bleeding disorders presents with severe systemic hemorrhage. Blood tests reveal normal platelet counts but a failure in the intrinsic clotting cascade, specifically at the step where a cofactor is required by Factor IXa to activate Factor X. Further analysis detects autoantibodies against this specific cofactor. Which of the following statements correctly identifies the targeted factor and distinguishes this pathogenesis from classic Hemophilia A?
Options
- A.
The autoantibodies target Factor VIII, disrupting the enzymatic amplification required for prothrombinase formation; unlike classic Hemophilia A, which is an X-linked recessive genetic deficiency of the same factor.
- B.
The autoantibodies target Factor IX, preventing the conversion of fibrinogen to fibrin; whereas classic Hemophilia A is an autosomal recessive disorder affecting the same factor.
- C.
The autoantibodies target Thrombokinase, directly inhibiting the conversion of prothrombin to thrombin; unlike classic Hemophilia A, which is caused by a genetic mutation in platelets.
- D.
The autoantibodies target Factor VIII, leading to a failure in the extrinsic pathway; whereas classic Hemophilia A is a genetic defect causing the overproduction of heparin.
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Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Regulatory_Failure
Understand how NOT, EXCEPT, and logical constraints are used to manipulate exam results.
Concepts Behind This Question
Factor VIII|Autoantibodies|Hemophilia A
Why This Question Is Tricky
Common Mistakes
The Conceptual Pivot lies in distinguishing between the genetic etiology of classic Hemophilia A (an X-linked recessive mutation causing a lack of production) and the autoimmune etiology of Acquired Hemophilia (autoantibodies neutralizing an already produced factor).
It also tests the precise location of Factor VIII in the cascade (intrinsic pathway, upstream of prothrombinase formation) rather than confusing it with direct thrombin or fibrinogen action.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Body Fluids and Circulation - Class 11 |
| Concept | Clotting Cascade Factors |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |