Which of the following is a correct match

Options

A. Down syndrome - 21st chromosome
B. Sickel-cell anaemia-x-chromosome
C. Haemophilia-y-chromosome
D. Parkinson's disease-x-and-y-chromosome

Answer

To solve the question "Which of the following is a correct match?", we will analyze each option provided and determine if the matches between the diseases and chromosomes are accurate.

### Step-by-Step Solution:

1. **Analyze Option A: Down Syndrome and 21st Chromosome**
- Down syndrome is caused by the presence of an extra copy of the 21st chromosome, a condition known as trisomy 21.
- **Conclusion**: This is a correct match.

2. **Analyze Option B: Sickle Cell Anemia and X Chromosome**
- Sickle cell anemia is caused by a mutation in the hemoglobin beta gene, which is located on the 11th chromosome, not the X chromosome.
- **Conclusion**: This is an incorrect match.

3. **Analyze Option C: Hemophilia and Y Chromosome**
- Hemophilia is an X-linked disorder, meaning it is caused by mutations on the X chromosome, not the Y chromosome.
- **Conclusion**: This is an incorrect match.

4. **Analyze Option D: Parkinson's Disease and X and Y Chromosomes**
- Parkinson's disease is associated with genetic alterations on chromosome 4 (alpha-synuclein gene) and chromosome 6 (parkin gene), not the X or Y chromosomes.
- **Conclusion**: This is an incorrect match.

### Final Conclusion:
The only correct match from the provided options is:
- **Option A: Down Syndrome - 21st Chromosome**