Genes recently shown to be mutated in ALS include the DNA/RNA binding proteins TAR DNA binding protein 43 (TDP-43) and Fused-in-sarcoma (FUS) [3-6], and C9ORF72, the latter being a major cause of familial and sporadic ALS [7,8]. The gene discussed is C9orf72; the disease is amyotrophic lateral sclerosis.