Huntington disease can strike at an earlier age and bring about a more rapid degeneration and death in successive generations within a family. this phenomenon can be explained by which mechanism?
a. presence of a transposable element in the gene.
b. chronic exposure to mutagens in the environment.
c. expansion of a trinucleotide repeat in the coding sequence of the gene.
d. presence of an extra chromosome in the germ line.
e. absence of a gene product that is involved in dna repair.