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

Multiple Choice

The heritable disorder fragile X syndrome, a major cause of intellectual disability, is caused by

A) production of enzymes that break the phosphate backbone.
B) UV light.
C) X-rays.
D) the presence of an extra X chromosome in the sperm or egg.
E) the expansion of a region of trinucleotide repeats.