A genomic condition that may be responsible for some forms of fragile X syndrome,as well as Huntington disease,involves ________.
A) plasmids inserted into the FMR-1 gene
B) various lengths of trinucleotide repeats
C) multiple breakpoints fairly evenly dispersed along the X chromosome
D) multiple inversions in the X chromosome
E) single translocations in the X chromosome

Question

Quizplus · Accepted Answer

Fragile X syndrome and Huntington disease are both caused by expansions of trinucleotide repeats in specific genes (FMR-1 and HTT, respectively). In Fragile X syndrome, the expansion of CGG repeats within the FMR-1 gene can result in a loss of function of the FMRP protein, leading to the characteristic symptoms of the syndrome. In Huntington disease, the expansion of CAG repeats within the HTT gene leads to the production of a mutant huntingtin protein that aggregates in neurons and causes neurodegeneration. Therefore, the answer is B, various lengths of trinucleotide repeats.

A Genomic Condition That May Be Responsible for Some Forms