To date, there are four mendelian genes that cause ALS: The Cu–Zn superoxide dismutase (SOD1), TAR DNA Binding Protein (TARDBP), Fused in Sarcoma (FUS) gene and Chromosome 9 Open Reading Frame 72 (c9orf72) (Table 1). The gene discussed is FUS; the disease is amyotrophic lateral sclerosis.