Neuronal degeneration and loss are pathological hallmarks of ALS and AD,[22, 23] whereas GAP43 promotes neuronal growth and repair.[24] In this study, we found that GAP43 mRNA was significantly downregulated following TDP‐43 depletion in cortical neurons capable of differentiation, as well as in AD brains with pathological pTDP‐43. This evidence concerns the gene TARDBP and Alzheimer disease.