While the majority of ALS cases are considered to occur sporadically, a notable subset of approximately 10% of patients of European ancestry have a familial form linked primarily to the GGGGCC hexanucleotide repeat expansion (RE) within the C9orf72 gene (chromosome 9 open‐reading‐frame 72) (Veldink 2017). This evidence concerns the gene C9orf72 and amyotrophic lateral sclerosis.