Which one is correctly matched?

Options

A. Erythroblastisis syndrome X-linked
B. Down 's syndrome
C. Klinefelter's syndrome -44+XXY
D. Colour blindness -Y- linked

Answer

To determine which option is correctly matched, we will analyze each option provided in the question step by step.

### Step-by-Step Solution:

1. **Erythroblastosis Syndrome**:
- This condition occurs when an Rh-negative mother is pregnant with an Rh-positive child, typically when the father is Rh-positive.
- The mother's immune system may produce antibodies against the Rh factor, leading to complications in subsequent pregnancies.
- This condition is classified as an autoimmune disorder, not an X-linked disorder.
- **Conclusion**: This option is **incorrect**.

2. **Down Syndrome**:
- Down syndrome is caused by the presence of an extra copy of chromosome 21, known as trisomy 21.
- The typical chromosomal notation for Down syndrome is 47 chromosomes, with the composition being 45 + XX or 45 + XY (indicating the presence of an extra chromosome).
- Since no specific matching description is given in the option, we cannot confirm it as correctly matched.
- **Conclusion**: This option is **incorrect**.

3. **Klinefelter Syndrome**:
- Klinefelter syndrome is characterized by the presence of one or more extra X chromosomes in males.
- The typical chromosomal notation for Klinefelter syndrome is 47 chromosomes, with the composition being 44 + XXY, 44 + XXXY, or even 44 + XXXXXY (indicating the presence of additional X chromosomes).
- This matches the description provided in the option.
- **Conclusion**: This option is **correct**.

4. **Color Blindness**:
- Color blindness is primarily an X-linked recessive disorder, meaning it is carried on the X chromosome and affects males more frequently.
- It is not a Y-linked disorder.
- **Conclusion**: This option is **incorrect**.

### Final Conclusion:
The only correctly matched pair is **Klinefelter syndrome**, which is represented as 44 + XXY.

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