Which among the following statement(s) is/are correct about Down syndrome?

1. Down syndrome is also known as trisomy of 21st chromosome.
2. $1^{st}$discovered chromosomal abnormality in human beings.
3. The affected individual has 46 chromosomes in their cells.

1. Both 1 and 2
2. Only 3
3. Both 1 and 3
4. 1, 2 and 3

The correct option is A Both 1 and 2
Down syndrome arises due to the presence of an additional copy of chromosome 21. It was the first discovered and described chromosomal disorder in human beings. The affected individual has 47 chromosomes in their cells. Children suffering from Down’s syndrome are usually mentally retarded and have a short lifespan.