More than 100 mutations distributed throughout the 153-residue SOD1 polypeptide have been shown to cause ALS; the common features of several ALS-SOD1 mutants have been characterized in vitro, such as the capability to generate oxidants, instability, a higher sensitivity to denaturing conditions and the propensity to form aggregates [2]–[9]. This evidence concerns the gene SOD1 and amyotrophic lateral sclerosis.