C9orf72 and amyotrophic lateral sclerosis: The mutations in this gene are responsible for about 2–5% of all ALS cases across all races [11], [12], SOD1 remained the most common mutated gene related to ALS until the discovery of the GGGGCC hexanucleotide repeat expansion in C9orf72 in ALS patients in 2011 [13], [14].