Which one of the following is a chromosomal disorder

Options

A. Haemophila
B. Down's syndrome
C. Phenylketonuria
D. Sickle-cell anaemia

Answer

To determine which of the provided options is a chromosomal disorder, we can analyze each option step by step.

### Step 1: Identify the Options
The options provided are:
1. Hemophilia
2. Down syndrome
3. Phenylketonuria
4. Sickle cell anemia

### Step 2: Analyze Each Option

#### Option 1: Hemophilia
- **Description**: Hemophilia is a blood clotting disorder.
- **Genetic Basis**: It is classified as a sex-linked recessive disorder.
- **Conclusion**: Hemophilia is not a chromosomal disorder.

#### Option 2: Down Syndrome
- **Description**: Down syndrome is characterized by developmental delays and physical features.
- **Genetic Basis**: It is caused by trisomy of chromosome 21, meaning there is an extra copy of this chromosome.
- **Conclusion**: Down syndrome is a chromosomal disorder.

#### Option 3: Phenylketonuria
- **Description**: Phenylketonuria (PKU) is a metabolic disorder.
- **Genetic Basis**: It is an autosomal recessive disorder.
- **Conclusion**: PKU is not a chromosomal disorder.

#### Option 4: Sickle Cell Anemia
- **Description**: Sickle cell anemia affects the shape of red blood cells.
- **Genetic Basis**: It is also an autosomal recessive disorder caused by a mutation in the hemoglobin gene.
- **Conclusion**: Sickle cell anemia is not a chromosomal disorder.

### Step 3: Final Conclusion
After analyzing all the options, the only chromosomal disorder among the choices is **Down syndrome**.

### Answer:
**Down syndrome** is the chromosomal disorder.

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