Question

Down’s syndrome is caused due to ______.

Options

• monosomy of 21st chromosome

• trisomy of 21st chromosome

• an extra Y-chromosome in male

• an extra X-chromosome in female

Answer 1

Down’s syndrome is caused due to trisomy of 21st chromosome.

Explanation:

Down’s syndrome is caused by the presence of an extra copy (trisomy) of chromosome 21, resulting in 47 chromosomes instead of the normal 46. This chromosomal abnormality arises due to non-disjunction during gamete formation and leads to characteristic physical features, mental retardation, and sometimes heart defects in affected individuals.