The more recently discovered hexanucleotide repeat expansions in the Chromosome 9 open reading frame 72 (C9orf72) gene are by far the most common genetic causes of ALS as these repeat expansions instigate 30%–50% of fALS (DeJesus-Hernandez et al., 2011; Renton et al., 2011; Van Blitterswijk et al., 2012). Here, C9orf72 is linked to amyotrophic lateral sclerosis.