HTT and early-onset autosomal dominant Alzheimer disease: Huntington’s disease ischaracterized by selective death of GABAergic striatal neurons[3], while dopaminergic neurons ofthe substance nigra are what are mainly affected in Parkinson’s disease[4], and preferential loss of hippocampalneurons occurs in Alzheimer’s disease [5].To date, several mechanisms are believed to contribute to the pathogenesis of HD,including the new toxic properties of mutant Htt (mHtt), concomitantly with thedysfunction of normal Htt [6].