Trisomy-21 is termed as

Question

Accepted Answer

Trisomy-21 is termed as Down syndrome, which is correctly identified as Option 4. Here is a detailed explanation supporting this:

1. **Explanation for Option 4 (Down syndrome):**
   - Down syndrome is a genetic disorder caused by the presence of an extra copy of chromosome 21, hence the term "Trisomy-21." This means that individuals with Down syndrome have three copies of chromosome 21 instead of the usual two. This extra genetic material affects the development of the individual, leading to the characteristic features and developmental challenges associated with the condition. Common features include intellectual disability, distinct facial appearance, and potential for various health issues such as heart defects and thyroid problems. The association between Trisomy-21 and Down syndrome is well-established in medical genetics.

2. **Explanation for why other options are incorrect:**

- **Option 1 (Klinefelter's syndrome):**
     - Klinefelter's syndrome is a condition that affects males and is caused by the presence of an extra X chromosome, resulting in a 47,XXY karyotype. It is not related to chromosome 21, and therefore, it is not associated with Trisomy-21. Symptoms of Klinefelter's syndrome can include reduced testosterone levels, infertility, and some learning difficulties, but these are distinct from the features of Down syndrome.

- **Option 2 (Sickle cell disease):**
     - Sickle cell disease is a genetic blood disorder caused by a mutation in the hemoglobin gene on chromosome 11, leading to the production of abnormal hemoglobin S. This condition results in the distortion of red blood cells into a sickle shape, causing various health complications such as anemia, pain episodes, and increased risk of infections. It is unrelated to chromosome 21 and does not involve trisomy.

- **Option 3 (Turner's syndrome):**
     - Turner's syndrome is a condition that affects females and is characterized by the partial or complete absence of one of the X chromosomes, resulting in a 45,X karyotype. It is not associated with an extra chromosome 21, and thus, it is not related to Trisomy-21. Features of Turner's syndrome include short stature, infertility, and certain physical abnormalities, which are different from those seen in Down syndrome.

In conclusion, Option 4 is the correct answer because Down syndrome is directly caused by Trisomy-21, while the other options describe conditions that are unrelated to the presence of an extra chromosome 21.