Which is correctly matched?

Options

A. A parkinsons's disease -X and Y- chromosomses
B. Haemophilia-Y chromosomes
C. Down's syndrome -21 st chromosome
D. Stickle cell anaemia -X dchromosomes

Answer

To determine which option is correctly matched, we need to analyze each condition and its associated chromosome(s):

1. **Parkinson's Disease**:
- Parkinson's disease is primarily associated with genetic alterations on chromosomes 4 and 6.
- The statement that it is related to X and Y chromosomes is incorrect.

2. **Hemophilia**:
- Hemophilia is a genetic disorder that is linked to mutations in the genes located on the X chromosome.
- The statement that it is associated with the X chromosome is correct, but if the question implies a different chromosome, then it would be incorrect.

3. **Down Syndrome**:
- Down syndrome is caused by the presence of an extra copy of chromosome 21 (trisomy 21).
- The statement that it is related to chromosome 21 is correct.

4. **Sickle Cell Anemia**:
- Sickle cell anemia is caused by a mutation in the beta-globin gene located on chromosome 11.
- The statement that it is associated with the X chromosome is incorrect.

**Conclusion**:
The only correctly matched condition is **Down syndrome with chromosome 21**.

### Steps:
1. Identify the genetic condition being discussed.
2. Determine the chromosome(s) associated with each condition.
3. Compare the provided information with known genetic associations.
4. Identify which condition has the correct chromosome match.