Approximately 5–10% of patients are diagnosed with familial ALS, caused by mutations in various genes, including SOD1, fused in sarcoma, TAR DNA-binding protein, and dynactin subunit 1; patients with sporadic ALS constitute approximately 90% of the cases, while the causes for this form of ALS have not been defined. The gene discussed is FUS; the disease is amyotrophic lateral sclerosis.