HD is inherited in an autosomal dominant manner and is caused by expanded CAG (Cytosine-Adenine-Guanine) repeats (≥36) in exon I of the huntingtin coding gene (IT15), resulting in expression of the mutant huntingtin protein (mHTT) with an abnormal number of glutamine repeats (polyQ, ≥36) in its N-terminus [3,4]. Here, HTT is linked to Huntington disease.