Interestingly, mutations in genes encoding proteins in the mGluR1 signaling pathway, that result in activation of this pathway, have been linked to ataxia in several cases, including the Moonwalker ataxic mouse model20 and the late-onset, dominantly inherited human diseases SCA1 (MIM: 164400),21 SCA2 (MIM: 183090),22 SCA28 (MIM: 610246),23 and SCA41 (MIM: 616410),24 which share common clinical features with the individuals carrying GRM1 missense mutations in the present study. This evidence concerns the gene GRM1 and cerebellar ataxia.