SOD1 and amyotrophic lateral sclerosis: ALS patients with C9orf72 expansions showed hyperexcitability as a feature of only symptomatic ALS patients (Geevasinga et al., 2015; Schanz et al., 2016), while other studies showed that cortical hyperexcitability appears early in the disease process in sALS patients (Eisen et al., 1993; Prout and Eisen, 1994; Mills and Nithi, 1997; Ziemann et al., 1997; Vucic and Kiernan, 2006), and precede the onset of the disease in fALS patients with SOD1 mutation (Vucic et al., 2008).