Disjunction of the 21st chromosome that can lead to Down syndrome has been found to be related to
A)paternal age.
B)maternal age.
C)multiple codon repeats on the X chromosome.
D)the inability to metabolize phenylalanine.

Question

Disjunction of the 21st chromosome that can lead to Down syndrome has been found to be related to​ 
A)paternal age. 
B)maternal age. 
C)multiple codon repeats on the X chromosome. 
D)the inability to metabolize phenylalanine.

Quizplus · Accepted Answer

Disjunction of the 21st chromosome is directly related to maternal age. The likelihood of disjunction increases with increasing maternal age, particularly after the age of 35.

Disjunction of the 21st Chromosome That Can Lead to Down