Huntington’s disease (HD) is a progressive, neurodegenerative disease caused by a CAG expansion in exon 1 of the huntingtin (HTT) gene, resulting in the formation of a prolonged polyglutamine (polyQ) tract in the N-terminal region, which leads to the production of a toxic mutant huntingtin protein (mHTT) [231]. Here, HTT is linked to neurodegenerative disease.