Twenty-one of the Chinese sALS cases, five fALS probands and two of the controls harboured such variants (Additional file 1: Table S7; see Additional file 1: Table S8 for details of variants in NEK1, SOD1 and TBK1 that passed filters for gene-based testing, screening of known ALS variants or both). This evidence concerns the gene SOD1 and amyotrophic lateral sclerosis.