SMN1 and amyotrophic lateral sclerosis: The dramatic clogging of distal axons by aberrant mitochondria and amorphous structures documented here along with the remarkable mitochondrial alterations quantified within the muscle of SMA mice are a witness of potential defects in transport mechanisms, which are known to occur in both ALS and SMA (Wen et al. 2010; Natale et al. 2015; Xu et al. 2016; Limanaqi et al. 2017).