Fragile-X syndrome usually occurs as a result of
A) paternal age.
B) maternal age.
C) unusually high codon repeats on the X chromosome.
D) the inability to metabolize phenylalanine.

Question

Quizplus · Accepted Answer

Fragile-X syndrome is caused by an abnormally high number of CGG trinucleotide repeats on the X chromosome. These repeats can cause methylation and inactivation of the FMR1 gene, leading to a loss of FMRP protein production and the characteristic symptoms of Fragile-X syndrome. Paternal and maternal age as well as the inability to metabolize phenylalanine are not associated with the development of Fragile-X syndrome.

Fragile-X Syndrome Usually Occurs as a Result of