BDNF and Huntington disease: The reduction of wt HTT and expression of mutant HTT have been shown to decrease the levels of the neurotrophic factor BDNF (Zuccato et al., 2001), and this decrease has been observed in many HD models as well as in HD patients (Ferrer et al., 2000; Duan et al., 2003; Zhang et al., 2003).