HTT and juvenile Huntington disease: A progressive neurodegenerative disorder, Huntington’s disease, causes uncontrolled movements known as chorea that involve involuntary jerking or twitching movements.93 The patients also show dominant emotional and behavioral alterations.94 This disease is known to be caused by an increase in the CAG segment repeat (around 35-120) in the HTT gene, which forms the huntingtin protein.