Amyotrophic lateral sclerosis is diagnosed as sporadic disease [sporadic ALS (sALS)] in about 90% of all patients, while in the remaining cases of familial origin at least 100 different gain-of-function mutations are found in the ALS1 gene coding for the SOD1 enzyme, by itself accounting for about 20% of all familial cases (7). The gene discussed is SOD1; the disease is amyotrophic lateral sclerosis.