HTT and Huntington disease: The formation of abnormal protein aggregates in neurons has been a research hotspot in neurodegenerative diseases, such as Lewy body-containing alpha-synuclein in PD, amyloid beta (Aβ) plaques in AD, and mutant huntingtin cytoplasmic inclusions in Huntington’s disease (HD), etc (Wisniewski and Konietzko, 2008; Arrasate and Finkbeiner, 2012; Rocha et al., 2018).