Mongoloid idiocy in human beings - caused by the trisomy of chromosome 21 is also known

Options

A. Down's syndrome
B. Turner's syndrome
C. Klinefelter's syndrome
D. Tay - sachs disease

Answer

**Step-by-Step Solution:**

1. **Understanding the Question:**
The question asks about a specific genetic condition known as "mongoloid idiocy," which is caused by the trisomy of chromosome 21.

2. **Identifying the Options:**
The options provided are:
- A) Down syndrome
- B) Turner syndrome
- C) Klinefelter syndrome
- D) Tay-Sachs disease

3. **Analyzing Each Option:**
- **Option A: Down syndrome**
- Down syndrome is indeed caused by the presence of an extra copy of chromosome 21, which is referred to as trisomy 21. This condition is characterized by developmental delays and physical features associated with the syndrome.
- **Option B: Turner syndrome**
- Turner syndrome affects females and is characterized by the complete or partial absence of one of the X chromosomes (45,X). This is not related to chromosome 21.
- **Option C: Klinefelter syndrome**
- Klinefelter syndrome occurs in males who have an extra X chromosome (47,XXY). This is also unrelated to chromosome 21.
- **Option D: Tay-Sachs disease**
- Tay-Sachs disease is a genetic disorder caused by a deficiency of the hexosaminidase A enzyme, not related to trisomy of chromosome 21.

4. **Conclusion:**
After analyzing all the options, it is clear that the only correct answer is **A) Down syndrome**, as it is the condition caused by trisomy of chromosome 21.

**Final Answer:**
Mongoloid idiocy in human beings, caused by the trisomy of chromosome 21, is also known as **Down syndrome**.

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