OPTN and amyotrophic lateral sclerosis: Activation of the unfolded protein response (UPR) and ER stress are well-documented pathogenic features in human ALS patients (Ilieva et al., 2007; Atkin et al., 2008; Oyanagi et al., 2008; Walker et al., 2010) and in animal/cellular disease models associated with mutant FUS, TDP-43, C9orf72, optineurin, and SOD1 (Atkin et al., 2006; Oh et al., 2008; Walker and Atkin, 2011; Farg et al., 2012; Walker et al., 2013; Zhang et al., 2014; Sundaramoorthy et al., 2015).