If a man has one premutation allele for fragile X syndrome, what is the probability that he will pass the premutation allele on to his son?
A)100%
B)75%
C)50%
D)25%
E)0%

Question

Quizplus · Accepted Answer

Fragile X syndrome is linked to the X chromosome. Men have one X and one Y chromosome. When a man passes on his genes, he gives either his X chromosome to his daughters or his Y chromosome to his sons. Since the premutation allele for Fragile X syndrome is on the X chromosome, and sons receive their father's Y chromosome, a man cannot pass the premutation allele for Fragile X syndrome to his sons.

If a Man Has One Premutation Allele for Fragile X