SOD1 and amyotrophic lateral sclerosis: Nevertheless, 5–10% of ALS is familial, and more than 20 gene mutations have been identified, such as Cu/Zn superoxide dismutase 1 gene (SOD1), TAR DNA-binding protein 43 (TDP43), fused in sarcoma (FUS)/translocated in sarcoma and ubiquitin 2.