C9orf72 and amyotrophic lateral sclerosis: Given that C9ORF72 mutations are the most frequent mutation in ALS, FALS and FTD, understanding the function of the gene and the effects of its mutation have been extensively investigated (Gijselinck et al., 2012; van Blitterswijk et al., 2013; Maharjan et al., 2017; Gossye et al., 2020).