This is consistent with reports of aberrant motor axon morphology associated with ALS-related genes including TDP-43 (Kabashi et al., 2010), SOD1 (Clark et al., 2016; Lemmens et al., 2007; Ramesh et al., 2010) and C9orf72 (Burguete et al., 2015; Ciura et al., 2013). Here, SOD1 is linked to amyotrophic lateral sclerosis.