<prompt> The over-expression of a trinucleotide repeat causesParkinsons diseaseCaissons diseaseAddisons diseaseHuntingtons disease  <response>: D Huntingtons disease Trinucleotide repeat expansions cause a number of chronic neuro degenerative disease. Most of them are late onset and cell deaths is prominent in all of them. The mutations occurs in open reading frames of the gene involved, with the expansions being smaller than those found in the fragile chromosome conditions. Examples Huntingtons disease. Fragile X syndrome. X-linked spino bulbar muscular atrophy. Myotonic dystrophy. 