Interestingly, animal models containing a knockout of the C9orf72 protein do not experience motor dysfunction (Burberry et al., 2016; O'Rourke et al., 2016; Sudria-Lopez et al., 2016), suggesting that a loss of function due to haploinsufficiency would not be a main pathogenic mechanism in C9-ALS patients. Here, C9 is linked to amyotrophic lateral sclerosis.