Question

Down syndrome is an example of trisomy. How many chromosomes will each cell of an individual have in Down syndrome?

Answer 1

One less than a normal person

Answer 2

sometimes, an error occurs when the 46 chromosomes are being divided in half, and an egg or sperm cell keeps both copies of the #21 chromosome instead of just one copy. If this egg or sperm is fertilized, then the baby will have three copies of the #21 chromosome, which is called trisomy 21, or Down syndrome.