Furthermore, HDAC inhibitors improve molecular, cellular and behavioral phenotypes in animal models for a number of neurodegenerative diseases including HD [6], [29]–[34], Parkinson's disease [35], spinal and bulbar muscular atrophy [36], Alzheimer's disease [37], [38], dentatorubral-pallidoluysian atrophy [39], amyotrophic lateral sclerosis [40], [41] and Friedreich's ataxia [42]. Here, HDAC9 is linked to early-onset autosomal dominant Alzheimer disease.