Several HDAC inhibitors have now been evaluated for the treatment of a variety of genetic disorders, such as spinal muscular atrophy (SMA) (Garbes et al., 2009; Hahnen et al., 2006; Kernochan et al., 2005; Riessland et al., 2006), Huntington disease (Butler and Bates, 2006; Hockly et al., 2003; Thomas et al., 2008), cardiac hypertrophy (Antos et al., 2003) and cystic fibrosis (Hutt et al., 2010). The gene discussed is HDAC9; the disease is Huntington disease.