Among the fALS cases, 20% are associated with dominantly inherited mutations in the superoxide dismutase 1 (SOD1) gene [2], but a few other ALS-causative genes have been identified, including ALS2/alsin [3], ALS4/senataxin [4] and ALS8/VAPB (vesicle associated membrane protein B) [5]. Here, SOD1 is linked to amyotrophic lateral sclerosis.