A disease caused by an autosomal primary non-disjunction is

Options

A. Down's syndome
B. Klinefelter's syndrome
C. turner's syndrome
D. sickle cell anemia

Answer

**Step-by-Step Solution:**

1. **Understanding Non-Disjunction**: Non-disjunction refers to the failure of homologous chromosomes or sister chromatids to separate properly during cell division. This can lead to gametes with an abnormal number of chromosomes.

2. **Identifying the Types of Non-Disjunction Disorders**: Non-disjunction can occur in autosomes (non-sex chromosomes) or sex chromosomes. We are looking for a disease caused by autosomal non-disjunction.

3. **Evaluating the Options**:
- **Down Syndrome**: This condition is caused by the non-disjunction of chromosome 21, resulting in an extra chromosome (trisomy 21).
- **Klinefelter Syndrome**: This is caused by the presence of an extra X chromosome in males (XXY), which is a sex chromosome disorder.
- **Turner Syndrome**: This condition occurs in females who have only one X chromosome (X0), also a sex chromosome disorder.
- **Sickle Cell Anemia**: This is a genetic disorder caused by a mutation in the hemoglobin gene, not by non-disjunction.

4. **Conclusion**: Among the options provided, Down Syndrome is the only condition caused by autosomal primary non-disjunction, specifically involving chromosome 21.

5. **Final Answer**: The disease caused by an autosomal primary non-disjunction is **Down Syndrome**.

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