The heritable disorder Fragile X syndrome, a major cause of mental retardation, is caused by
A)production of enzymes that break the phosphate backbone.
B)UV light.
C)X-rays.
D)presence of an extra X chromosome in the sperm or egg
E)duplication of multiple three-nucleotide repeats.

Question

Quizplus · Accepted Answer

Fragile X syndrome is caused by the expansion of the CGG trinucleotide repeat affecting the FMR1 gene on the X chromosome, leading to its dysfunction.

The Heritable Disorder Fragile X Syndrome, a Major Cause of Mental