Question

Trisomic condition of Down's syndrome arises due to

• A. Triploidy
• B. Translocation
• C. Non-disjunction
• D. Both A and C

Answer 1

Answer: (D)

Both A and C

Down's syndrome or trisomy 21, is a genetic disorder and symptoms associated with this include delayed physical growth, mild to moderate, intellectual disability along with certain characteristic facial features. Majority of the cases of this genetic disorder is caused when three copies genes are present on chromosome 21 instead of two. The triploidy is either due to the failure of the 21st chromosome to separate (non-disjucntion) during egg or sperm development resulting with extra copy. In around 2-4% cases, the presence of extra chromosomal content is due to the extra chromosome 21 material may also occur due to a translocation.

Therefore, the correct answer is option D.