A fatal central nervous system disorder caused by a copy number variation in which more than 35 repetitions of a particular set of three base pairs are present is _____.
A) Down syndrome
B) nearsightedness
C) fragile X syndrome
D) Huntington's disease

Question

Quizplus · Accepted Answer

The disorder described is Huntington's disease, in which a repeat of the CAG triplet is present more than 35 times, leading to a toxic buildup of the huntingtin protein in neurons of the brain. Down syndrome is caused by a whole extra copy of chromosome 21, while fragile X syndrome is caused by a repeat expansion of the CGG triplet in the FMR1 gene. Nearsightedness is a refractive error of the eye and not related to genetic disorders caused by repeat expansions.

A Fatal Central Nervous System Disorder Caused by a Copy