Chen et al. generated MNs and non-MNs derived from ALS SOD1 iPSC to reveal that neurofilament aggregation is an early event in ALS pathogenesis, resulting from the dysregulation of NF subunit proportion caused by SOD1 mutant binding NF-L mRNA in MNs (Chen et al., 2014). The gene discussed is SOD1; the disease is amyotrophic lateral sclerosis.