More than 30 ALS genes have been previously identified; in monogenic disease the most frequent mutations are found within C9ORF72, SOD1, TARDBP and FUS. Changes in known ALS genes are found in ~21% of ALS patients, and the presence of more than one variant is associated with lower age of onset (2). The gene discussed is SOD1; the disease is amyotrophic lateral sclerosis.