To summarize, this study is the first to compare the functional impact of ALS-linked TDP-43 mutations on RNP transport in neurons and combine this approach with a systematic mutagenesis study to identify conserved structural elements, aromatic and charged residues that are key determinants of TDP-43 RNP granule transport in the axon. The gene discussed is RNPC3; the disease is amyotrophic lateral sclerosis.