Familial ALS, which represents only ~10% of total ALS, has been linked to mutations of over a dozen different genes, most commonly superoxide dismutase 1 (SOD1), TAR DNA binding protein 43 (TDP-43), fused in sarcoma (FUS) and C9orf72 [6]; mutations of these genes can also be detected in subjects who present with sporadic ALS. The gene discussed is C9orf72; the disease is amyotrophic lateral sclerosis.