A baby is diagnosed with Down syndrome shortly after birth.Which of the following events occurred abnormally during prenatal development?

Question

Quizplus · Accepted Answer

Down syndrome is caused by the presence of an extra copy of chromosome 21. This occurs during meiosis when nondisjunction occurs, meaning the chromosomes fail to separate properly during anaphase. The resulting gamete (sperm or egg) that receives two copies of chromosome 21 will contribute to the fetus having Down syndrome. Therefore the abnormal event during prenatal development that leads to Down syndrome is anaphase of meiosis.

A Baby Is Diagnosed with Down Syndrome Shortly After Birth