SOD1 and amyotrophic lateral sclerosis: In 1993, mutations in SOD1 were associated to familial autosomal dominant Amyotrophic Lateral Sclerosis (ALS), and nowadays they represent the second most common cause of sporadic (up to 7% of cases) and familial ALS giving rise to up to 20% of cases with an autosomal dominant or recessive inheritance, with more than 150 variants (Fig. 1) identified in different geographic populations [2–4].