C9orf72 and amyotrophic lateral sclerosis: The most common and most well established mutations contributing to ALS pathology are found in Cu-Zn superoxide dismutase 1 (SOD1), TDP-43, FUS and a hexanucleotide expansion repeat in Chromosome 9 Open Reading Frame 72 (C9orf72) (Chia et al., 2018).