GRM5 and amyotrophic lateral sclerosis: Many individual components of this neural‐glial signalling pathway, such as mGluR5 signalling and purinergic signalling have been independently verified as dysregulated in ALS models and patients (Cieślak et al. 2019; Ng et al. 2015; Ferré et al. 2002; Bonifacino et al. 2019; Aronica et al. 2001).