ALS-causing mutant TDP-43 and FUS, which play crucial roles in the normal processing of long mRNA, are also major components of the protein aggregates observed in motor neurons of familial forms of ALS (except SOD1-ALS), as well as sporadic cases of ALS in the absence of TDP-43 and FUS mutations (Arai et al., 2006; Neumann et al., 2006). Here, SOD1 is linked to amyotrophic lateral sclerosis.