Which pair of diseases are caused by genes lacated on X- chromosomes

Options

A. Colour blindness, albinism
B. Colour blindness, hypertrichosis
C. Colour blindness , phenylketonura
D. Colou blindness, haemophilia.

Answer

To determine which pair of diseases are caused by genes located on the X chromosomes, we can analyze each option provided in the question.

### Step-by-Step Solution:

1. **Understand the Types of Disorders**:
- Identify the nature of each disorder mentioned in the options: whether they are X-linked or autosomal.

2. **Analyze Option A**:
- **Color Blindness**: This is an X-linked recessive disorder caused by a defect in genes located on the X chromosome.
- **Albinism**: This is an autosomal recessive disorder caused by a defect in melanin production and is not linked to the X chromosome.
- **Conclusion**: This option is incorrect because albinism is not X-linked.

3. **Analyze Option B**:
- **Color Blindness**: As previously mentioned, this is X-linked.
- **Hypertrichosis**: This can be either autosomal or X-linked depending on the type. However, it is not definitively X-linked.
- **Conclusion**: This option is also incorrect because hypertrichosis is not exclusively X-linked.

4. **Analyze Option C**:
- **Color Blindness**: X-linked recessive.
- **Phenylketonuria (PKU)**: This is an autosomal disorder caused by a defect in the gene located on chromosome 11.
- **Conclusion**: This option is incorrect since PKU is not X-linked.

5. **Analyze Option D**:
- **Color Blindness**: X-linked recessive.
- **Hemophilia**: This is also an X-linked recessive disorder caused by mutations in genes on the X chromosome.
- **Conclusion**: This option is correct as both diseases are X-linked recessive disorders.

### Final Answer:
The correct pair of diseases caused by genes located on the X chromosomes is **Color Blindness and Hemophilia**.

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