<prompt> All of the following diseases are associated with trinucleotide repeat sequence except:Huntingtons diseaseFredreichs ataxiaMyotonica dystrophyHereditary motor-sensory neuropathy  <response>: Rest of the options are associated with trinucleotide repeat sequence. Triple-repeat mutations Allelic expansion disorders Due to an increase in the number of nucleotide repeats above a ceain threshold Length of the nucleotide repeat often correlates with the severity of the disease Anticipation: When repeat length increases from one generation to the next, disease manifestations may worsen or be observed at an earlier age. Disease Repeats Clinical features Fragile X-Syndrome CGG Mental retardation, large ears and jaws, macroorchidism in males Myotonic Dystrophy Chromosome 19 CTG Muscle loss, cardiac arrhythmia , cataracts , frontal balding Huntington;s disease CAG Affective disorder Spinocerebellar ataxia type 1 CAG Progressive ataxia, dysahria, dysmetria Friedreich;s ataxia GAA Progressive ataxia, dysahria , hyperophic cardiomyopathy Ref: Nelson textbook of Medical Physiology 21st edition Pgno: 647 