Depression occurs in up to 15% of patients receiving tetrabenazine treatment for Huntington's disease (Jankovic and Beach, 1997; Kenney et al.,2006), and since it acts as an inhibitor of the vesicular monoamine transporter, VMAT2, it has similar monoamine depleting effects as the known pro‐depressant drug, reserpine (Quinn et al.,1959; Zheng et al.,2006). This evidence concerns the gene SLC18A2 and Huntington disease.