The mechanism by which mutations in TAR DNA‐binding protein 43 (TDP‐43) cause neurodegeneration remains incompletely understood. In this issue of The EMBO Journal, Fratta et al (2018) describe how a point mutation in the C‐terminal low complexity domain of TDP‐43 leads to the skipping of otherwise constitutively conserved exons. In vivo, this mutation triggers late‐onset progressive neuromuscular disturbances, as seen in amyotrophic lateral sclerosis (ALS), suggesting that TDP‐43 splicing gain‐of‐function contributes to ALS pathogenesis.