HDAC9 and neurodegenerative disease: In fact, preclinical studies to evaluate the effect of HDAC inhibitors in HD have inspired other neurodegenerative diseases, including additional trinucleotide repeat (TNR) diseases (for review see Evans-Galea et al., 2013) PD, Alzheimer disease (AD), and amyotrophic lateral sclerosis (ALS) (Xu et al., 2011; Lazo-Gomez et al., 2013; Sharma and Taliyan, 2015a).