The most common genetic causes of familial ALS, explaining about 70% of all familial ALS cases in the Western world, are missense mutations in the superoxide dismutase 1 (SOD1), TAR DNA binding protein 43 (TARDBP), and fused in sarcoma (FUS) genes as well as hexanucleotide expansions in the chromosome 9 open reading frame 72 (C9orf72) gene [1]. Here, C9orf72 is linked to amyotrophic lateral sclerosis.