Which of the following most appropriately describes haemophilia ?

Options

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

Answer

To determine which option most appropriately describes hemophilia, we can analyze the characteristics of the disorder step by step.

### Step-by-Step Solution:

1. **Understanding Hemophilia**:
- Hemophilia is commonly referred to as "Bleeder's disease." It is characterized by delayed blood clotting, which can lead to excessive bleeding.

2. **Identifying the Genetic Basis**:
- Hemophilia is caused by a deficiency in certain clotting factors, which are proteins necessary for blood coagulation. The genes responsible for these factors are located on the sex chromosomes.

3. **Determining the Type of Inheritance**:
- Hemophilia is inherited in a specific manner. It is a recessive disorder, meaning that an individual must inherit two copies of the mutated gene (one from each parent) to express the disease. However, since the gene is located on the X chromosome, it predominantly affects males, who have only one X chromosome.

4. **Classifying the Disorder**:
- Given that hemophilia is linked to the X chromosome and is recessive in nature, it is classified as an X-linked recessive disorder. This means that females can be carriers (having one copy of the mutated gene) without showing symptoms, while males will express the disorder if they inherit the affected X chromosome.

5. **Evaluating the Options**:
- Now, let's evaluate the options provided:
- **Dominant gene disorder**: Incorrect, as hemophilia is not dominant.
- **Recessive gene disorder**: Partially correct, but does not specify that it is X-linked.
- **X-linked recessive gene disorder**: Correct, as it accurately describes the inheritance pattern of hemophilia.
- **Chromosomal disorder**: Incorrect, as hemophilia is a Mendelian disorder, not a chromosomal one.

6. **Conclusion**:
- The most appropriate description of hemophilia is "X-linked recessive gene disorder."

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