SOD1 and amyotrophic lateral sclerosis: The most common genetic causes of ALS are hexanucleotide expansions in the C9orf72 gene responsible for 30–46% of familial ALS (fALS), mutations in the superoxide dismutase 1 (SOD1) gene accounting for 12–20% of all fALS and mutations in the TARDBP gene (encoding for TDP-43) responsible for ~ 5% of fALS cases [1].