C9orf72 and amyotrophic lateral sclerosis: Mutations in more than 30 different genes, including superoxide dismutase 1 (SOD1), TAR DNA-binding protein 43 (TARDBP), fused in sarcoma (FUS), and the intronic hexanucleotide repeat expansion in the C9orf72 gene, are currently associated with both familial and sporadic ALS, even though sporadic cases account for 90–95% of all cases [8].