GRIA2 and amyotrophic lateral sclerosis: Furthermore, in the majority of the patients with sporadic ALS, considerable proportions of motor neurons in the spinal cord express abnormal glutamine/arginine (Q/R) site-unedited GluA2 (a subunit of the α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptor (Kawahara et al, 2004; Kwak & Kawahara, 2005)) because of reduced expression of an RNA editing enzyme called adenosine deaminase acting on RNA 2 (ADAR2) (Aizawa et al, 2010; Hideyama et al, 2012).