Which clotting factor is absent in haemophilia A?

Options

A. factor X
B. factor IX
C. factor VIII
D. factor IV

Answer

**Step-by-Step Solution:**

1. **Understanding Haemophilia A**: Haemophilia A is a genetic disorder that affects the blood's ability to clot. This condition is primarily caused by a deficiency in a specific clotting factor.

2. **Identifying Clotting Factors**: There are several clotting factors involved in the blood coagulation process, each designated by a number (Factor I, II, III, etc.). In the context of haemophilia, the relevant factors are Factor VIII (8), Factor IX (9), and Factor XI (11).

3. **Determining the Absent Factor in Haemophilia A**: In Haemophilia A, the specific clotting factor that is deficient or absent is Factor VIII (8). This deficiency leads to problems with blood clotting, resulting in prolonged bleeding.

4. **Reviewing Other Types of Haemophilia**: It’s important to note that Haemophilia B is associated with a deficiency of Factor IX (9), and Haemophilia C is related to Factor XI (11). However, these are not relevant to Haemophilia A.

5. **Conclusion**: Based on the information, the correct answer to the question "Which clotting factor is absent in haemophilia A?" is Factor VIII (8).

**Final Answer**: Factor VIII (8) is absent in Haemophilia A.

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