HTT and Huntington disease: For example, AD is characterized by the formation of senile plaques that present with β-amyloid deposition in the cerebral cortex (Braak and Braak, 1991), PD by the formation of Lewy bodies containing α-synuclein in the neurons of the substantia nigra (Spillantini et al., 1998) and HD by intranuclear inclusions containing of mutant huntingtin protein (Yu et al., 2003).