Which of the following most appropriately describes haemophilia?

Options

A. Chrosomal disorder
B. Dominant gene disorder
C. Recessive gene disorder
D. X-linked recessive gene disorder

Explanation

**Step-by-Step Solution:**

1. **Understanding Hemophilia:**
- Hemophilia is a genetic disorder characterized by excessive bleeding due to the absence of certain clotting factors in the blood.

2. **Identifying the Genetic Basis:**
- Hemophilia is caused by a defect in a gene located on the X chromosome. This makes it an X-linked disorder.

3. **Classification of Hemophilia:**
- Hemophilia is classified as a recessive disorder. This means that for a person to exhibit the symptoms of hemophilia, they must inherit the defective gene from both parents (in females) or from one parent (in males).

4. **Types of Hemophilia:**
- There are two main types of hemophilia:
- **Hemophilia A:** Caused by a deficiency of clotting factor VIII.
- **Hemophilia B:** Caused by a deficiency of clotting factor IX.

5. **Distinguishing from Other Disorders:**
- Hemophilia is not a chromosomal disorder, which involves the gain or loss of entire chromosomes. Instead, it is a Mendelian disorder, meaning it follows the inheritance patterns described by Gregor Mendel.

6. **Conclusion:**
- The most appropriate description of hemophilia is that it is an X-linked recessive genetic disorder.

**Final Answer:**
Hemophilia is best described as an X-linked recessive genetic disorder.

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