SOD1 and amyotrophic lateral sclerosis: In Caucasian ALS patients the most recurring genetic defects are observed in C9orf72 (familial ALS (fALS) 33.7%, sporadic ALS (sALS) 5.1%), followed by SOD1 (fALS 14.8%, sALS 1.2%), TARDBP (fALS 4.2%, sALS 0.8%) and FUS (fALS 2.8%, sALS 0.3%)41.