Since mHtt is known to alter transcriptional regulation and apoptosis (Kim et al., 1999; Rigamonti et al., 2000; Cui et al., 2006), it is likely that the reduction in mHtt following chronic mGluR5 inhibition reduces the loss of striatal neurons and nurture the neurotrophic capacity in HD brains. Here, GRM5 is linked to Huntington disease.