SOD1 and amyotrophic lateral sclerosis: Approximately 10% of ALS is familial (fALS), associated with mutations in copper/zinc superoxide-dismutase-1 gene (SOD1), fused in sarcoma/translocated in liposarcoma gene (FUS/TLS), TDP-43, valosin containing protein (VCP) and a hexanucleotide expansion of the C9orf 72 (chromosome 9 open reading frame 72) gene.