SMN2 and amyotrophic lateral sclerosis: Both FUS and TDP-43 colocalize with SMN in subnuclear gems and ALS-associated mutations in FUS and TDP-43 reduce gem localization of SMN (Shan et al., 2010; Yamazaki et al., 2012; Gerbino et al., 2013; Groen et al., 2013; Ishihara et al., 2013; Sun et al., 2015).