Altered mGluR activity has been reported in SCA1 and SCA2 mouse models (Liu et al., 2009; Power et al., 2016b), while in humans, several rare forms of cerebellar ataxia result from mutations in genes in this cascade (Yabe et al., 2003; van de Leemput et al., 2007; Guergueltcheva et al., 2012; Zanni et al., 2012) implying that dysfunction in mGluR1 signaling and downstream calcium homeostasis could be common pathophysiological mechanisms in spinocerebellar ataxia (Schorge et al., 2010). Here, GRM1 is linked to aceruloplasminemia.