Down syndrome is caused by
A) improper migration of brain cells during brain development.
B) an inherited faulty gene.
C) a genetic error in which a vital enzyme is missing in the brain.
D) the presence of an extra twenty-first chromosome.
E) obstetric difficulties at the time of birth.

Question

Quizplus · Accepted Answer

Down syndrome is caused by the presence of an extra twenty-first chromosome. This can occur during the formation of reproductive cells or during early fetal development. It is not inherited from parents and is not caused by environmental factors or obstetric difficulties at the time of birth.

Down Syndrome Is Caused by