What is the source of the extra chromosome 21 in an individual with Down syndrome?
A)Nondisjunction in the mother only
B)Nondisjunction in the father only
C)Duplication of the chromosome
D)Nondisjunction or translocation in either parent
E)It is impossible to detect with current technology

Question

Quizplus · Accepted Answer

Down syndrome can be caused by nondisjunction, which is the failure of chromosomes to separate during meiosis, or translocation, where a part of chromosome 21 attaches to another chromosome. Nondisjunction or translocation can occur in either parent.

What Is the Source of the Extra Chromosome 21 in an Individual