A 5-year-old male presents with mental retardation and is diagnosed with Fragile X syndrome. When the parents ask what caused this, the nurse practitioner responds with:
A) translocation of the Philadelphia chromosome.
B) nondisjunction of chromosome 21.
C) expansion of cytosine-guanine-guanine (CGG) repeats 200.
D) mutation in the transmembrane conductance regulator.

Question

Quizplus · Accepted Answer

Fragile X syndrome is caused by the expansion of CGG repeats in the FMR1 gene on the X chromosome.

A 5-Year-Old Male Presents with Mental Retardation and Is Diagnosed