Down syndrome results from flaws in the parents' egg or sperm cells, a condition called
A) Trisomy-21.
B) phenylketonuria (PKU).
C) Fragile-X.
D) cretinism.

Question

Quizplus · Accepted Answer

Down syndrome is caused by the presence of an extra chromosome 21 in the individual's cells, a condition known as trisomy-21. This usually occurs spontaneously during the formation of the egg or sperm cells in the parents, rather than being inherited from them.

Down Syndrome Results from Flaws in the Parents' Egg or Sperm